EEVblog #484 - Home Solar Power System Installation

[EEVblog]

Installing and initial testing of Dave's 3kW home solar power system. With Sunnyboy SMA inverter, 250W LG Mono-X solar panels, and net metering.

Data from the system is here: http://pvoutput.org/list.jsp?userid=22501

[Eliminateur]

why do you have two power meters in the old installation?
ripple control, wth is that for?

[Skimask]

Something I've never been able to grasp...

How does power get fed back into the grid?

Is it as simple as just generating one more volt than the grid has on it at that particular point in time (e.g. keeping everything in phase, etc.)?
Do you monkey with the phasing of the power you generate in relation to that of the phase of the power on the grid itself (e.g lead or lag an equal pk-pk voltage by x degrees)?

If all grids were DC, this would be a no-brainer, but it's not...

[c4757p]

ripple control, wth is that for?

A higher-frequency ripple tone (1050 Hz IIRC) is injected into the mains to mark off-peak hours; that receives the signal and switches a water heater on or off accordingly.

[c6r1s]

Very nice indeed. I wonder could we modify to increase efficiency of Solar panels. What if we were to put a TEG system along the back of the panels and rails to generate excess DC to feed back into the inverter.? I mean if you harness more of the loses wouldn't that increase your DC feedback to save more money?

[cthree]

Amazing how much you pay and how little you get paid wtf. We pay $0.06-$0.12 and get paid $0.53 in Ontario Canada. Used to get paid $0.80 which was stupid so they stopped doing it. Something about encouraging solar generation investment or some such.

[Deagle]

Haha Dave, going through the installers toolbag 

[NiHaoMike]

Are you going to design some sort of controller to try to match the load to the supply at all times? I suppose the difficulty of actually doing that depends on the time resolution of the measurements.

Something I've never been able to grasp...

How does power get fed back into the grid?

Is it as simple as just generating one more volt than the grid has on it at that particular point in time (e.g. keeping everything in phase, etc.)?
Do you monkey with the phasing of the power you generate in relation to that of the phase of the power on the grid itself (e.g lead or lag an equal pk-pk voltage by x degrees)?

If all grids were DC, this would be a no-brainer, but it's not...

Just generate a waveform that is in phase with and slightly higher voltage than the mains. It's very similar to a synchronous motor drive.

[IanB]

When you run a generator feeding a grid you actually have to make the phase angle of the generator lead the grid by marginal amount. The generator will naturally try to synchronize with the grid, and the attempt of the generator to resist being driven out of phase relates to the power you have to feed into the generator to force it into the out of phase situation. The more power you feed into the generator the faster it tries to turn and the more the grid resists it. The generator pushing against the grid is how power gets transferred.

[Leon]

The SMA SB 21-series is fanless. The fan is an option, if you didn't order it you won't find it during a teardown. 

[Hypernova]

Why are there no combined elec/water heating setups? You run pipe along the back of the panels to cool them and you get free hot water. Why is it that when ever I see a solar set up it's always either one but never both?

[IanB]

I don't think you would get much hot water if most of the sun's energy is being converted to electricity. By energy balance you can get hot water or electricity, but not both at the same time. If you did run water cooling you would get low grade heat (lukewarm water only) and then you would need a heat pump to raise the water to a useful temperature. I doubt that the improved efficiency of the cooled panels would generate enough extra power to run the heat pump. Not to mention the considerably increased complexity and capital cost of the installation.

[Eliminateur]

panels should already include piping for that, and you run the water for your overhead water tanks that you have anyway so it doesn't matter if they get lukewarm only (or the downpipe from the tank to the house)

[Hypernova]

I don't think you would get much hot water if most of the sun's energy is being converted to electricity. By energy balance you can get hot water or electricity, but not both at the same time. If you did run water cooling you would get low grade heat (lukewarm water only) and then you would need a heat pump to raise the water to a useful temperature. I doubt that the improved efficiency of the cooled panels would generate enough extra power to run the heat pump. Not to mention the considerably increased complexity and capital cost of the installation.

The panels are not that efficient, most of the light is still turning into waste heat and the panels can get to 50+ degrees easily.
If you are already using electric based water heaters you already spend power on the heaters, so giving the heater warm water to start with will save power. Solar water heater installations are often augmented by electrical heaters already. What I'm proposing is free cooling for the panels and free preheating for the heaters.

[snoopy]

Something I've never been able to grasp...

How does power get fed back into the grid?

Is it as simple as just generating one more volt than the grid has on it at that particular point in time (e.g. keeping everything in phase, etc.)?
Do you monkey with the phasing of the power you generate in relation to that of the phase of the power on the grid itself (e.g lead or lag an equal pk-pk voltage by x degrees)?

If all grids were DC, this would be a no-brainer, but it's not...

Yes the inverter generates a sinewave with the same phase but with a higher voltage than the mains and it also has a high output impedance approaching current drive. If there are too many inverters on the grid it can drive the actual mains voltage too high and all inverters have an over voltage limit to shut them down when this happens. They also have a feature called anti-islanding which means that if the grid and mains fails the inverter will shut down thus making the grid safe.

regards
david

[snoopy]

Installing and initial testing of Dave's 3kW home solar power system. With Sunnyboy SMA inverter, 250W LG Mono-X solar panels, and net metering.

6 cents per KWh gives new meaning to daylight robbery

cheers

[notsob]

When dave grabbed the installers meter - I was waiting for a 'mine is bigger than yours' segway

[Skimask]

When you run a generator feeding a grid you actually have to make the phase angle of the generator lead the grid by marginal amount. The generator will naturally try to synchronize with the grid, and the attempt of the generator to resist being driven out of phase relates to the power you have to feed into the generator to force it into the out of phase situation. The more power you feed into the generator the faster it tries to turn and the more the grid resists it. The generator pushing against the grid is how power gets transferred.

Is "super-synchronous" the word I'm looking for?
If it is, then unless I'm wrong, it appears to me that a purely mechanical solution would be a relative piece of cake compared to designing/programming/using a solid state inverter.

[Leon]

Why are there no combined elec/water heating setups? You run pipe along the back of the panels to cool them and you get free hot water. Why is it that when ever I see a solar set up it's always either one but never both?

There are plenty attempts:
http://solarwall.com/en/products/pvthermal.php
http://www.tessolarwater.com/index_en.html?zeuspv-t.html&2
But the problem is, you need to be able to get rid of the heat accumulated by the thermal part of the panel. Solar thermal collectors are often stagnating in the summer, they heat up to the point steam is produced and the collector is actually getting dry as the fluid is pushed out of the collector. Temperatures of 170 degrees celcius and up are possible, this would seriously harm PV cells or at least reduce production significantly.

[duskglow]

I was just reading up on 1050hz ripple today - or more accurately, watching youtubes of it.  There are some interesting ones of the ripple actually being generated.  Here's one:

[jnissen]

Your net metering pay back is awful. Here we get paid 12.8 cents/KWH generated. It used to be very poor like that when it was first installed but last year they changed from a net metering to a gross type. I have to pay for whatever I pull from the grid at from 1.8-11.8 cents/KWH but every KWH I generate it's paid at the higher 12.8! Went from a payback of 8 to 9 years to less than 5 for me. In fact I sized my system and have yet to pay for bill since January! As our summer cranks up I suspect I may soon have a bill as the AC is running often.

So your sunny boy communicates via Bluetooth to the PC? My system uses power line communications and a receiver box plugs into the AC line and then an ethernet cable to that. I like the idea of directly to bluetooth. Hopefully you can figure out the communication issue so the data can be seen live. Does Sunnyboy offer a web service to view the data?

[Strada916]

Dave download Sunny Explorer from SMA website. Also there is an android app so you can connect to the inverter via Bluetooth.

Why they did not install an import/export meter instead of two meters is beyond me.

[KedasProbe]

Here in Belgium your meter (before solar panels installation) is the same and will turn backward when you generate more than you use. You don't get money if the total is negative.
So you try to get the average use to 0 or a little lower when they check your usage. They did just add a tax though on using the net to put energy on. (as a buffer)
(53 Euro/installed kW each year, with an extra meter they will tax you with what you really put on the net)

[michaelc]

Just watched your solar install video... very interesting. 

I wonder why the installer didn't adjust the height of the rails on the brackets to offset the "undulating" roof structure.  I know in the end it doesn't really matter... but the brackets have elongated holes, why not use them to make the rails straight?

I have 3.04 kW (16 x 190W) of ET panels and a SMA SB5000TL-20 inverter.  My system was registered with the South Australian distribution company (SA Power Networks) as a 4.94 kW system, I can add another 10 x 190W panels without losing my feed in tariff...  IIRC 44c/kWh from the governemnt FIT scheme and 6c/kWh from my energy retailer.

I use software called PV Bean Counter to read solar info from the inverter, this then uploads to www.pvoutput.org in five minute intervals.

http://www.pvoutput.org/intraday.jsp?id=5514&sid=5863

The next step is to transfer the Bluetooth read and upload functions to a Raspberry Pi and eliminate the need to keep a power hungry PC running!

Michael.

[EEVblog]

I use software called PV Bean Counter to read solar info from the inverter, this then uploads to www.pvoutput.org in five minute intervals.
http://www.pvoutput.org/intraday.jsp?id=5514&sid=5863
The next step is to transfer the Bluetooth read and upload functions to a Raspberry Pi and eliminate the need to keep a power hungry PC running!

Exactly what I'm doing:
http://pvoutput.org/list.jsp?userid=22501
Using a netbook at the moment, and it's not live feeding, have to sort that out. But yes, I want to transition to a R.Pi or something.
Or could just let it update once every day instead of live.
Next step is consumption data with a Watts Clever unit.

[(*steve*)]

It's interesting that because they pay you less than it costs you per unit that it becomes economical to move your consumption away from those times when total consumption is lowest.

It seems to be counterproductive.

I get paid substantially more per unit than it costs me.  The effect is that I try to reduce my consumption and move the rest to off-peak hours.

Another trick is that with 3 phase power, and my airconditioner on a different phase to the solar, I actually get paid while my airconditioner is running.  They try to put the solar on the "most used" phase, but in my case they picked another phase from the one used by the airconditioner.

What I'd really like to see is something that can take the output of a solar panel and use it to supplement the power to an appliance, with any excess load powered by the mains.  It seems to be a far better option than guerrilla solar and shouldn't fall foul of any power regulations.  Is such a device possible?

[Monkeh]

That little 'fuse box' is an.. interesting way of doing things. Don't think I've seen such a contraption in service for a while.

Is that a steel sheet it's all secured to?

[manicdoc]

I wish Dave the best of luck with his solar set up. I've been 50/50 over going solar power based, too many external variables for my liking, plus it has been somewhat of a political football. Be most interested in the figures and how it stacks up to doing things on the consumption side of the equation.

Currently we use evacuated tube solar hot water and roof space heat reclaiming (Ventis) with passive solar design & thermal mass (plus a forced air wood fire for winter) - we have no air con, don't need it.

[Dreso12]

Combining solar thermal and PV is possible but I will involve redesign of the whole Panels. The problem is not only over heating is also electrical safety, back of the panels are isolated by a really thin sheet of polyester or tedlar any small hole or scratch make an isolation problem if the back is in water. Installations are often at voltages of 600 v or more.
I used to manufacture PV panels and believe me, the back isolation is really thin and any scratch can cause isolation problems even in rainy days so better not to put it in direct contact with liquids for a long time. There were even some fires in Germany years ago due to scratches in the back of pannels mounted in wooden roofs.
I don't recommend you doing this with commercial modules as they are not design for that.

[lewis]

I used to manufacture PV panels and believe me, the back isolation is really thin and any scratch can cause isolation problems even in rainy days so better not to put it in direct contact with liquids for a long time.

Obviously you wouldn't have the water in direct contact with the back of the panel, that would be stupid. You'd use a thermally bonded pipe to form a heat exchanger.

[madires]

The panels are not that efficient, most of the light is still turning into waste heat and the panels can get to 50+ degrees easily.
If you are already using electric based water heaters you already spend power on the heaters, so giving the heater warm water to start with will save power. Solar water heater installations are often augmented by electrical heaters already. What I'm proposing is free cooling for the panels and free preheating for the heaters.

Got solar panels (non PV) for water heating and supporting the central heating on the roof. On a sunny day in the summer the temperature goes up to 160° celsius. In the winter it's about the half for a sunny day.

When I watched the video I first thought WTF, everything's outside, the mains distribution, gas, the boiler and the inventer. Over here (nearly) all homes got a cellar, so everything's inside. And the few homes whithout a cellar got a dedicated utility room for all that stuff.

[SeanB]

Sydney does not exactly get extreme weather, no snow, a little hail and the odd tropical cyclone do roll through, but no extremes of temperature and massive snow loads. Sticking it all outside makes it cheaper to maintain, even if the lifetime is slightly shorter due to solar radiation degrading the plastics and the rust that will appear.

[madires]

Yes the inverter generates a sinewave with the same phase but with a higher voltage than the mains and it also has a high output impedance approaching current drive. If there are too many inverters on the grid it can drive the actual mains voltage too high and all inverters have an over voltage limit to shut them down when this happens. They also have a feature called anti-islanding which means that if the grid and mains fails the inverter will shut down thus making the grid safe.

That simplifies the installation but is a bad feature IMHO. I'd like an optional mains contactor to disconnect the grid and run my little island if the grid has an outage. If the grid is online again the inverter would need to re-synchronize to the grid. Of course the inverter needs a sensing input from the grid, i.e. parallel to the mains contacter. And if the inverter it's synchronized it would connect the grid again.

[Eliminateur]

When I watched the video I first thought WTF, everything's outside, the mains distribution, gas, the boiler and the inventer. Over here (nearly) all homes got a cellar, so everything's inside. And the few homes whithout a cellar got a dedicated utility room for all that stuff.

yeah i found that odd too, i mean the fuixebox is publicly accesible!!!, that's a big "NO NO"!!.
not even a transparent window so that the utility guys can meter without opening it!.

over here the meter lies on the downpost from the overhead lines(or underground downtown) with a transparent plexiglas window(it's not a protruding wall-installed box but an embedded one), the door has a special secure lock that only utility guys have a key to access.
That box is han
On another small box lies YOUR side of the grid per-se where you have to put two big screw-in ceramic fuses(they look from around 1920ish) in what iirc is a lot like an edison screw, the fuse is actually a strand of wire(the fuse itself has two screws to replace the "fusing element"), if it blows you essentiually eyeball it.

after that it's all inside the house, if the fusebox where to be accesible like that it would take days for someone to shut-it off it in the middle of the night, break in and rob/kill/rape everyone for hours.

our water/heater tank is also inside the house, no dedicated room per-se(it's a small room without a door) and they design is vastly different, Dave's look like some industrial HVAC unit.

Also, i don't remember seeing a differential breaker(or at least not in the configuration i'm used to, which is that king of fat/boxy front ones), that strickes me as odd

[Eliminateur]

That simplifies the installation but is a bad feature IMHO. I'd like an optional mains contactor to disconnect the grid and run my little island if the grid has on outage. If the grid is online again the inverter would need to re-synchronize to the grid. Of course the inverter needs a sensing input from the grid, i.e. parallel to the mains contacter. And if the inverter it's synchronized it would connect the grid again.

i can think of a cool idea, if you have a generator you already have some sort of switchboard gear bypassing everything, i'd simply put the generator and the sunnyboy output to my internal line and isolate the grid, hence the gen would run mostly idling/peak loads and you'd save a ton of fuel when the grid goes down.
Or you need those solar system with battery banks....

[madires]

over here the meter lies on the downpost from the overhead lines(or underground downtown) with a transparent plexiglas window(it's not a protruding wall-installed box but an embedded one), the door has a special secure lock that only utility guys have a key to access.
That box is han
On another small box lies YOUR side of the grid per-se where you have to put two big screw-in ceramic fuses(they look from around 1920ish) in what iirc is a lot like an edison screw, the fuse is actually a strand of wire(the fuse itself has two screws to replace the "fusing element"), if it blows you essentiually eyeball it.

A typical mains distribution panel for a home looks like this one: http://1.bp.blogspot.com/_IlFRyHMSviA/TN70AWU7hYI/AAAAAAAAAEQ/1bh1C0vtB-Y/s1600/00000001.JPG The black cover will be replaced with the meter. And the main fuses are NH types (http://mschrod.de/Elektrik/Sicherungen/NH.jpg) with 35A (3 phase system is standard).

Also, i don't remember seeing a differential breaker(or at least not in the configuration i'm used to, which is that king of fat/boxy front ones), that strickes me as odd

RCDs are placed in the distribution panels for each flat/apartment/floor, or if there's just a single main distribution panel then it's placed there. A standard 3 phase one: http://www.voltus.de/out/pictures/generated/product/1/665_665_75/2CSF204201R3630.jpg.

[Monkeh]

over here the meter lies on the downpost from the overhead lines(or underground downtown) with a transparent plexiglas window(it's not a protruding wall-installed box but an embedded one), the door has a special secure lock that only utility guys have a key to access.
That box is han
On another small box lies YOUR side of the grid per-se where you have to put two big screw-in ceramic fuses(they look from around 1920ish) in what iirc is a lot like an edison screw, the fuse is actually a strand of wire(the fuse itself has two screws to replace the "fusing element"), if it blows you essentiually eyeball it.

A typical mains distribution panel for a home looks like this one: http://1.bp.blogspot.com/_IlFRyHMSviA/TN70AWU7hYI/AAAAAAAAAEQ/1bh1C0vtB-Y/s1600/00000001.JPG The black cover will be replaced with the meter. And the main fuses are NH types (http://mschrod.de/Elektrik/Sicherungen/NH.jpg) with 35A (3 phase system is standard).

Also, i don't remember seeing a differential breaker(or at least not in the configuration i'm used to, which is that king of fat/boxy front ones), that strickes me as odd

RCDs are placed in the distribution panels for each flat/apartment/floor, or if there's just a single main distribution panel then it's placed there. A standard 3 phase one: http://www.voltus.de/out/pictures/generated/product/1/665_665_75/2CSF204201R3630.jpg.

None of which is remotely like that used in other countries.

[Rufus]

Got solar panels (non PV) for water heating and supporting the central heating on the roof. On a sunny day in the summer the temperature goes up to 160° celsius.

That would be for steam heating then.

[M. András]

over here the meter lies on the downpost from the overhead lines(or underground downtown) with a transparent plexiglas window(it's not a protruding wall-installed box but an embedded one), the door has a special secure lock that only utility guys have a key to access.
That box is han
On another small box lies YOUR side of the grid per-se where you have to put two big screw-in ceramic fuses(they look from around 1920ish) in what iirc is a lot like an edison screw, the fuse is actually a strand of wire(the fuse itself has two screws to replace the "fusing element"), if it blows you essentiually eyeball it.

A typical mains distribution panel for a home looks like this one: http://1.bp.blogspot.com/_IlFRyHMSviA/TN70AWU7hYI/AAAAAAAAAEQ/1bh1C0vtB-Y/s1600/00000001.JPG The black cover will be replaced with the meter. And the main fuses are NH types (http://mschrod.de/Elektrik/Sicherungen/NH.jpg) with 35A (3 phase system is standard).

Also, i don't remember seeing a differential breaker(or at least not in the configuration i'm used to, which is that king of fat/boxy front ones), that strickes me as odd

RCDs are placed in the distribution panels for each flat/apartment/floor, or if there's just a single main distribution panel then it's placed there. A standard 3 phase one: http://www.voltus.de/out/pictures/generated/product/1/665_665_75/2CSF204201R3630.jpg.

None of which is remotely like that used in other countries.

we have similar boxes here but that big white one on mostly industrial or office sites or a multi flat building on the main distribution site

[ChrisGreece52]

Got solar panels (non PV) for water heating and supporting the central heating on the roof. On a sunny day in the summer the temperature goes up to 160° celsius.

That would be for steam heating then.

6 cents per Kwatt seems pretty cheap but if you think its long term its pretty ok

[madires]

None of which is remotely like that used in other countries.

How does a typical mains distribution look like in the UK?

[Monkeh]

None of which is remotely like that used in other countries.

How does a typical mains distribution look like in the UK?

I don't have any pictures on hand, Google works as well for you as me..

[Ed.Kloonk]

Haha Dave, going through the installers toolbag 

hmmm.

 

[madires]

How does a typical mains distribution look like in the UK?

I don't have any pictures on hand, Google works as well for you as me..

Does this one http://en.wikipedia.org/wiki/Distribution_board#Inside_a_UK_distribution_board match?

[Monkeh]

Not domestic stuff, no.

[Monkeh]

Internet, meet reality.

[martysdomain]

This is a fantastic thread/video. I wanted to get in that industry about four years ago, but didn't get the chance. It still is a topic of interest for me.

[dr.diesel]

This is a fantastic thread/video. I wanted to get in that industry about four years ago, but didn't get the chance. It still is a topic of interest for me.

Ditto.  Not really for the fact of saving money, but for the self reliance aspect.  First I've seen of that pvoutput website as well, all very interesting.

[madires]

Internet, meet reality.

Thanks! Wow! The local power companies would refuse to connect such distributions to the grid (maybe the first and the third).

[Monkeh]

Internet, meet reality.

Thanks! Wow! The local power companies would refuse to connect such distributions to the grid (maybe the first and the third).

Why? They're not unsound.

They're also not new installations, I picked the last two because they actually show the incoming service.

The real world is not shiny and new.

[M. András]

Internet, meet reality.

Thanks! Wow! The local power companies would refuse to connect such distributions to the grid (maybe the first and the third).

hahh, ive seen worse here in our house. 6mm2 aluminium wire stripped down approx 5cm then 6 1mm2 aluminium wire was just twisted onto that. insulation was burned about 2cm back on all of them. this was the neutral connection after the power meter in the owner accesible side, the earth connection was a little better but jes i would hang up the electrician who did that 30 years ago unfortunatly no pictures but i could show them for a few people over the years as a sign of shit work

[Eliminateur]

i don't like countries that are all uppity and anal-retentive about electrical code and certified electricians and all that, it's a bunch of red-tape BS.
that's why i like old installations better, with baquelite insulators, wooden backing, backelite switches(breakers?, who needs breakers, pfft).

At least over here you can put up a front "for appearances" witha single switch, they give you the ok then you wire your house whoever the hell you want.
in fact my house only has a single main breaker, that's it(apart from the maneuver switch for the generator), no segmented lines and all that BS, single fat line "bus bar" running through the house from which everything is derived/connected.(we wired the entire house ourselves being all technicians and related industries, wouldn't pay a dime for a dude to install it).
and i don't know if solar would be useful for us, roof is small compared the the surface of the house itself and has different shaped segments, plus the 2x 500L water tanks cast shadows, and our consumption is well into the MWh in summer (what with all the computers, aircons, basement workshop and all that)

[c4757p]

in fact my house only has a single main breaker, that's it(apart from the maneuver switch for the generator), no segmented lines and all that BS, single fat line "bus bar" running through the house from which everything is derived/connected.(we wired the entire house ourselves being all technicians and related industries, wouldn't pay a dime for a dude to install it).

I hope you keep a good stock of marshmallows to roast over your electrical fire.

[dr.diesel]

i don't like countries that are all uppity and anal-retentive about electrical code and certified electricians and all that, it's a bunch of red-tape BS.

To some point I agree, I'm a EE but not a certified electrician, quite capable of doing my own wiring.

On the flip side though, of the two houses I've owned, both pre-owned, the electrical work WAS ABSOLUTE garbage.  Miracle both didn't burn to the ground due to "DIYers" that had no business with a screw driver.

[c4757p]

Let's put it this way: I am absolutely in love with the fact that in this part of New York State, I can do my own electrical work for free. I am absolutely in fear of the fact that my neighbor can.

[dr.diesel]

Let's put it this way: I am absolutely in love with the fact that in this part of New York State, I can do my own electrical work for free. I am absolutely in fear of the fact that my neighbor can.

Well put, same here in Indiana, expect I have my 2nd Amendment rights as well!   Ha ha, sorry..

[c4757p]

Replace "do my own electrical work for free" for my opinion on that one 

[madires]

Thanks! Wow! The local power companies would refuse to connect such distributions to the grid (maybe the first and the third).

Why? They're not unsound.

They're also not new installations, I picked the last two because they actually show the incoming service.

The real world is not shiny and new.

Old installations got a right of continuance (not to meet current requirements) as long as they're not modified and met requirements when they were installed. If the power company connected the distribution back then it's fine. On the other hand if somethings bad happens the insurance won't pay and/or the owner of the building could face a lot of trouble in court.

[M. András]

in fact my house only has a single main breaker, that's it(apart from the maneuver switch for the generator), no segmented lines and all that BS, single fat line "bus bar" running through the house from which everything is derived/connected.(we wired the entire house ourselves being all technicians and related industries, wouldn't pay a dime for a dude to install it).

I hope you keep a good stock of marshmallows to roast over your electrical fire.

nah i ripped out all the goddam aluminium wiring 7 years ago and replaced with 2.5mm2 solidcore copper wires splitted even further then it was before with each socket chain ending its own braker. some part of the wiring was braked in with the plastic tubing and then plastered in when they did that, i was told they did this during that time preassemble the whole thing on the floor then put into the walls well had to remove some of the corners where the wiring was laid cos the idiot broke the plastic tubing and i couldnt get the wires out. we used up total of 80kg material to fill up the holes we had to make in the walls cos the shitty job of the builders of this house. i had doubt on the contact resistance of these:

but after all these years without problem, no these are not in the breaker box. unfortunatly i couldnt touch the incoming aluminium wiring unless i rip off the seals from the meter box. which i wont do, i just wait for the utility company to come and replace the meters in their usual intervallum around 10 years after the last replacement

[madires]

i had doubt on the contact resistance of these:

but after all these years without problem, no these are not in the breaker box.

Those connectors are standard for junction boxes for over 15 years :-)

[LaurenceW]

Dave, I've had a 4kWpk system running here in the UK for a couple of years, did a LOT of research beforehand, so am interested to compare your new installation. It looks good!

The SMA inverters are indeed the Dogs' Dangly Bits. As has been mentioned, your SB3000 does not come with a fan. The same casing and heatsink also serves in SMA's 5000W model (although that does have a fan). Since the fan is the only moving, and so least relaible part, I don't thnk you'll miss it! The fan on my SB4000 never comes on, anyway. And at ~97% efficiency, the inverter case only has to shed max 90W anyway.

The FREE Bluetooth Sunny Explorer software is well worth installing - lots of info available.

2kW from a 3kWpk system - in the middle of "winter" I'm not JEALOUS

[Rufus]

2kW from a 3kWpk system - in the middle of "winter" I'm not JEALOUS

But not as jealous as Dave is of the stupid of the stupid FIT you are getting?

[Eliminateur]

in fact my house only has a single main breaker, that's it(apart from the maneuver switch for the generator), no segmented lines and all that BS, single fat line "bus bar" running through the house from which everything is derived/connected.(we wired the entire house ourselves being all technicians and related industries, wouldn't pay a dime for a dude to install it).

I hope you keep a good stock of marshmallows to roast over your electrical fire.

the risk is negligible, we overrated everything.
and even if the electrical wiring shorted so hard to bring fire (well wires are flame retardant anyway) the house is not build on extremely flammable materials like in the US, we build like a friggin nuclear bunker, solid reinforced concrete and solid brick all over.
even if an entire room caught fire it would hardly affect the rest of the house the way it is built

[Bored@Work]

even if an entire room caught fire it would hardly affect the rest of the house the way it is built

Oh, it will. It is not the fire that kills you, it is the smoke.

[M. András]

agreed the plastic smoke is worse and yeah in a brick or concrete wall there is nothing what it can ignite 5cm deep in the wall

[Monkeh]

the risk is negligible, we overrated everything.
and even if the electrical wiring shorted so hard to bring fire (well wires are flame retardant anyway) the house is not build on extremely flammable materials like in the US, we build like a friggin nuclear bunker, solid reinforced concrete and solid brick all over.
even if an entire room caught fire it would hardly affect the rest of the house the way it is built

"No, I'm all—Aargh!"

[JackOfVA]

2kW from a 3kWpk system - in the middle of "winter" I'm not JEALOUS

But not as jealous as Dave is of the stupid of the stupid FIT you are getting?

There has been many comments on various ham radio boards about the radio frequency interference generated by neighbor's solar power systems - the inverter is the noise generator and apparently many inverters have little RFI suppression.

Have you observed any RFI on medium wave broadcast or FM band broadcast? (Assuming you are not also an amateur radio operator so you can observe the shortwave bands as well).

[Leon]

The same casing and heatsink also serves in SMA's 5000W model (although that does have a fan).

That is incorrect. All of the SB 21-series (they call them sunny boy with reactive power control), including the 4000 and 5000 use convection cooling. It's the previous 20-series that had "Opticool" in them (it uses a fan). See:
http://www.sma.de/produkte/solar-wechselrichter-ohne-transformator/sunny-boy-3000tl-3600tl-4000tl-5000tl-mit-reactive-power-control.html#Technische-Daten-3650

In the Netherlands we pay around € 0.22/kWh, FIT is € 0.22 until you reach your total usage, above that you get something like € 0.07-0.09. With 18x260Wp on our roof, let's say I look forward to the bill 

[DrGeoff]

I wish Dave the best of luck with his solar set up. I've been 50/50 over going solar power based, too many external variables for my liking, plus it has been somewhat of a political football. Be most interested in the figures and how it stacks up to doing things on the consumption side of the equation.

Currently we use evacuated tube solar hot water and roof space heat reclaiming (Ventis) with passive solar design & thermal mass (plus a forced air wood fire for winter) - we have no air con, don't need it.

I have to agree with this. I did the same with my new home, no AC, passive solar design and thermal inertia, and also the wodd fire for heating in winter. There's no gas where I am and we are right in the middle of a high risk bushfire zone so gas bottles are not an option. Solar hot water works really well, right throughout the year.

However when looking at PV solar there was too much Guvmint fiddling going on. I get to generate power when I don't want it, get 6c/kWh and then when I do want power in the evening I can't generate it so I get to pay 40c/kWh for it. I'd rather a power storage system or fuel cell generator with the grid solely as backup.

[Corporate666]

Can the utility companies just arbitrarily change the amount they pay you for putting power back into the grid?

I believe power here costs around $0.15 KWh, but the average in the USA is around $0.11.  Pretty crap that they charge you $0.20 but pay $0.06.  If they can just decide to drop it to $0.03 or whatever they like in the future, it would be a big factor in deciding whether to invest in a solar system.

[manicdoc]

I wish Dave the best of luck with his solar set up. I've been 50/50 over going solar power based, too many external variables for my liking, plus it has been somewhat of a political football. Be most interested in the figures and how it stacks up to doing things on the consumption side of the equation.

Currently we use evacuated tube solar hot water and roof space heat reclaiming (Ventis) with passive solar design & thermal mass (plus a forced air wood fire for winter) - we have no air con, don't need it.

I have to agree with this. I did the same with my new home, no AC, passive solar design and thermal inertia, and also the wodd fire for heating in winter. There's no gas where I am and we are right in the middle of a high risk bushfire zone so gas bottles are not an option. Solar hot water works really well, right throughout the year.

However when looking at PV solar there was too much Guvmint fiddling going on. I get to generate power when I don't want it, get 6c/kWh and then when I do want power in the evening I can't generate it so I get to pay 40c/kWh for it. I'd rather a power storage system or fuel cell generator with the grid solely as backup.

Yep solar generation and consumption are exactly out of phase with each other for us as well...

BTW - the only problem I've had over the years is the solar hot water pump controller 'failing' - when I cracked it open found a PIC and a cheap as chips mains relay that had burnt out on the contacts - replaced with a much higher rated relay and its been working fine since.. difference in cost - may 50c...

I also know a friend who was convinced to buy 8 evacuated tube units - to do combined hot water and pool heating - the 'con'tractor subsequently did a runner and she is now left with a half installed system doing nothing. I'm going to go round and check out how much is needed to get it going at least for the hot water. Shame she can't run a steam powered generator...

[DrGeoff]

Can the utility companies just arbitrarily change the amount they pay you for putting power back into the grid?

I believe power here costs around $0.15 KWh, but the average in the USA is around $0.11.  Pretty crap that they charge you $0.20 but pay $0.06.  If they can just decide to drop it to $0.03 or whatever they like in the future, it would be a big factor in deciding whether to invest in a solar system.

Not in NSW they can't, the tarrifs are regulated.
Smart metering means that you pay 48c/kWh during peak, about 20c/kWh shoulder and 12c/kWh low. I've been monitoring it for a while and it averages out to around 25c/kWh with our current usage. So the power companies are buying power from you at a very low rate to sell back to you at a much higher rate.

[EEVblog]

Can the utility companies just arbitrarily change the amount they pay you for putting power back into the grid?

Yes, not no. IPART have recommended prices for each state.
For NSW:
http://www.solarchoice.net.au/blog/nsw-solar-bonus-feed-in-tariff-scheme-final-report-released/

http://www.ipart.nsw.gov.au/Home/Industries/Electricity/Reviews/Retail_Pricing/Solar_feed-in_tariffs_-_2012-2013/27_Jun_2012_-_Media_Release_-_A_fair_and_reasonable_solar_feed-in_tariff_for_NSW/Media_Release_-_A_Fair_and_Reasonable_Solar_Feed-In_Tariff_for_NSW_-_June_2012

[ConKbot]

Jeeze, all these residential panels are to tiny compared to ones in the US. Ive seen bigger sub-panels in garages .

is an example of an absurdly neat US (and apparently canadian too, given by the original file name)

is a probably more average panel, nice lack of cable clamp on the big wire going out the bottom to a sub-panel. Thats a doorbell transformer on the right hand side of the panel.  Also, IIRC they are being naughty with the multiple wires under the ground/neutral bus bars, I think its supposed to be 1 wire per hole for neutrals, and upto 2 per hole for grounds. 

[DrGeoff]

Yep solar generation and consumption are exactly out of phase with each other for us as well...

BTW - the only problem I've had over the years is the solar hot water pump controller 'failing' - when I cracked it open found a PIC and a cheap as chips mains relay that had burnt out on the contacts - replaced with a much higher rated relay and its been working fine since.. difference in cost - may 50c...

I also know a friend who was convinced to buy 8 evacuated tube units - to do combined hot water and pool heating - the 'con'tractor subsequently did a runner and she is now left with a half installed system doing nothing. I'm going to go round and check out how much is needed to get it going at least for the hot water. Shame she can't run a steam powered generator...

Funny you should say that, I've been at Rheem a few times over the control algorithms.
During summer the tank thermostat will occassionally trip (it is resettable though) and the electrical heater won't turn on. It's usually not noticeable until we get a cloudy day or two. The temperature monitors I have all over the system alert me when the tank water temperature is dropping below a threshold that the off-peak electrical booster should have switched on so I can reset it. Seems that when the collectors pump out water that is too hot (above 85C it seems) then the thermostat trips, even though the tank temperature is still only around 50C. Would be better if the pump had variable flow control so when it is hot the flow is increased to keep the differential temperature lower.

[EEVblog]

Not in NSW they can't, the tarrifs are regulated.

No, they are voluntary on the part of each energy company based on the IPART recommendations.

Smart metering means that you pay 48c/kWh during peak, about 20c/kWh shoulder and 12c/kWh low. I've been monitoring it for a while and it averages out to around 25c/kWh with our current usage. So the power companies are buying power from you at a very low rate to sell back to you at a much higher rate.

Only if you get smart meters. They didn't install those on mine, so it seems they have no way to know my time of day usable to put me on such a scheme.
Smart meters are more popular and possibly mandatory for new installations in VIC?

[c4757p]

is an example of an absurdly neat US (and apparently canadian too, given by the original file name)

Neat freak here - looks just like mine!  I am proud of my absurdly neat wiring 

[DrGeoff]

Not in NSW they can't, the tarrifs are regulated.

No, they are voluntary on the part of each energy company based on the IPART recommendations.

Interesting, I didn't realise that. Makes it even worse than I thought.

Smart metering means that you pay 48c/kWh during peak, about 20c/kWh shoulder and 12c/kWh low. I've been monitoring it for a while and it averages out to around 25c/kWh with our current usage. So the power companies are buying power from you at a very low rate to sell back to you at a much higher rate.

Only if you get smart meters. They didn't install those on mine, so it seems they have no way to know my time of day usable to put me on such a scheme.
Smart meters are more popular and possibly mandatory for new installations in VIC?

We didn't have a choice. They were mandatory when the new house was built. I have 3 phases coming in and three smart meters (one includes the ripple control receiver as well). The metering box is on the outside wall and the distribution panel with around 30 RCD's on it is on the inside wall of the garage.

[EEVblog]

Interesting, I didn't realise that. Makes it even worse than I thought.

Yup 

We didn't have a choice. They were mandatory when the new house was built.

Ah, interesting. Mandatory for all new houses?
Who was the energy provider? Mine is Endevour Energy.

[DrGeoff]

We didn't have a choice. They were mandatory when the new house was built.

Ah, interesting. Mandatory for all new houses?
Who was the energy provider? Mine is Endevour Energy.

Energy Australia, or whatever they are calling themselves this week.
They just turned up and slapped 3 smart meters on the metering board and connected the cable between our pole and the street pole (wiring is underground, like yours).
The bill comes in with a whole lot of time-of-day usage information, but I've no way of checking whether it is accurate or a complete swindle!

[EEVblog]

I aso believe the smart meter rate and peak times are variable between providers as well.
Origin for example in VIC has a "peak" time from 1pm to 8pm, whcih would catch most people's major home usage. Nasty 

[EEVblog]

The bill comes in with a whole lot of time-of-day usage information, but I've no way of checking whether it is accurate or a complete swindle!

Yep, that's the shitty part.
Check to see if someone has hacked your meter and you can extract the data out yourself. Or the commands are available in the manual or whatever.

[DrGeoff]

The bill comes in with a whole lot of time-of-day usage information, but I've no way of checking whether it is accurate or a complete swindle!

Yep, that's the shitty part.
Check to see if someone has hacked your meter and you can extract the data out yourself. Or the commands are available in the manual or whatever.

There's an IR port which moght be interesting to connect to, and I got the meter manual from an online source which has the commands and button sequences. No detail on the interface though, but it is probably fairly rudimentary since the meter reader bloke uses it.

Energy Aust has peak time at 2pm - 8pm and shoulder from 7am to 2pm so they catch you from when the kids get home from school right through dinner time, when you use the most power. On weekends and public holidays there is no peak, it is shoulder from 7am to 10pm. In this case the solar installation would be providing power to you ate 20c/kWh, rather than into the grid at 6c/kWh so it has its uses, particularly at weekends.

[EEVblog]

In this case the solar installation would be providing power to you ate 20c/kWh, rather than into the grid at 6c/kWh so it has its uses, particularly at weekends.

Yeah, use it or sell it cheap.
I pay 21.85 cents + 5 cents green, so 26.85 all day.
Presumably that will not change with the new meters.

[yellowfruit]

Jeeze, all these residential panels are to tiny compared to ones in the US. Ive seen bigger sub-panels in garages .

Off the topic of solar, and correct me if I'm wrong but:

That would be, I believe, for two reasons. First that houses tend to be larger in the USA. Second that the voltage is lower (120V in the USA vs 240V in the UK, or thereabouts) necessitating more circuits. For example, a household ring main (for your fridge, computer, TV etc) in the UK is usually 30A, to support that current in the USA would require much thicker cable which would be harder to work with, pull through walls, etc etc. But generally there are similar numbers of sockets so instead there would be two 15A circuits (which I believe are single ended, not a loop like the UK).

Matt

[manicdoc]

Yep solar generation and consumption are exactly out of phase with each other for us as well...

BTW - the only problem I've had over the years is the solar hot water pump controller 'failing' - when I cracked it open found a PIC and a cheap as chips mains relay that had burnt out on the contacts - replaced with a much higher rated relay and its been working fine since.. difference in cost - may 50c...

I also know a friend who was convinced to buy 8 evacuated tube units - to do combined hot water and pool heating - the 'con'tractor subsequently did a runner and she is now left with a half installed system doing nothing. I'm going to go round and check out how much is needed to get it going at least for the hot water. Shame she can't run a steam powered generator...

Funny you should say that, I've been at Rheem a few times over the control algorithms.
During summer the tank thermostat will occassionally trip (it is resettable though) and the electrical heater won't turn on. It's usually not noticeable until we get a cloudy day or two. The temperature monitors I have all over the system alert me when the tank water temperature is dropping below a threshold that the off-peak electrical booster should have switched on so I can reset it. Seems that when the collectors pump out water that is too hot (above 85C it seems) then the thermostat trips, even though the tank temperature is still only around 50C. Would be better if the pump had variable flow control so when it is hot the flow is increased to keep the differential temperature lower.

Hmm, that is crazy. I must admit I have been toying with the idea of getting rid of the mindless controller and hooking it up to something more intelligent. I have an integrated alarm (Comfort) and lights (CBus) via Linux box. Although want to split that function off to a really small form factor dedicated box (PC104); has a database in it, so can't really be a micro controller solution. This could be the straw that convinces me to do it..

[DrGeoff]

Hmm, that is crazy. I must admit I have been toying with the idea of getting rid of the mindless controller and hooking it up to something more intelligent. I have an integrated alarm (Comfort) and lights (CBus) via Linux box. Although want to split that function off to a really small form factor dedicated box (PC104); has a database in it, so can't really be a micro controller solution. This could be the straw that convinces me to do it..

The system I designed uses a little PIC18 + 10bT ethernet module I developed that has all the I/O on it and have several of these scattered around the house on a network. They talk to a linux box which has the event handlers and databases and web interface to allow monitoring and control functions. Since I have the Linux server running 24/7 for mail server, dns cache and other things, there was no problem adding the control system to it. It's fairly lightweight in power consumption, just a core-2 processor on a motherboard and a couple of enterprise drives.
This has been running for several years now and I have some nice trend plots of temperature and other measurements that allow me to evaluate aspects of the house design and make improvements where necessary.

[hpnut]

Hi Dave,

interesting, I have a similar set-up.

10 x Bosch 245 watt modules EU30117
Sunny Boy 3000TL  inverter
Sunny Webbox Solar PV monitoring system


I am waiting to have the system connected to the grid next week.  here are some photos.

In Malaysia, we have a good FiT system that rewards early adopters of solar PV and other renewables such as wind and biomass.  www.seda.gov.my has details of the FiT mechanism.

Oh, Dave, you should re-position your rooftop antenna.  It will create partial shading and will cause your PV output to reduce. 

cheers,

hpnut from Putrajaya, Malaysia

[hpnut]

more pictures

[hpnut]

Haha Dave, going through the installers toolbag 

hmmm.

 

my service provider technicians had a Prova Solar Module Analyzer, I was jealous 

http://www.tes.com.tw/solare.htm

[Corporate666]

In this case the solar installation would be providing power to you ate 20c/kWh, rather than into the grid at 6c/kWh so it has its uses, particularly at weekends.

Yeah, use it or sell it cheap.
I pay 21.85 cents + 5 cents green, so 26.85 all day.
Presumably that will not change with the new meters.

Have you done any calculations about your total expected monthly generation vs. your bill?  Forgetting time-of-day issues, would you be a net exporter or net importer of grid energy? 

And I am guessing there must be companies making/selling some sort of energy storage solutions so you could save your overproduction for times when you have underproduction, no?  If so, is is not cost effective?

[DrGeoff]

I guess you also have to be careful about where you site it, and the owner takes on the risks if a neighbour plants a big tree or adds an extension or rebuild that overshadows the PC collectors and renders the system useless. I have heard of a couple of instances where an apartment block was built near some houses and wiped out a lot of their power generation with large shadows.

[senso]

Dumb question..
Why are the solar cells not full rectangles but instead have a triangular bit cut in the corners?

[ataradov]

They are made out of regular silicon, which comes in round discs. They don't cut to perfect squares because it wastes more material.

PS: I have no idea why they've cut corners from non-square cells shown above.

[jnissen]

http://pvoutput.org/intraday.jsp?id=19133&sid=16981

Catch up with me Dave! The tax incentives and rebates made a large system a reality for me. Yes I'm benefiting unfairly off your tax dollars! BTW - I didn't go solar to save the planet and all that garbage I only did it becuase I'm cheap! That and the fact the stock market of late has been up and down I invested in my home. It pays me monthly and not many investments were doing that for me. Here in central Texas the generated electricity can accumulate over the year. I generated quite a surplus earlier this year in the cool months when the AC was not running. Eating into the account now but still no electric bill yet this year!   

[EEVblog]

Have you done any calculations about your total expected monthly generation vs. your bill?  Forgetting time-of-day issues, would you be a net exporter or net importer of grid energy? 

Importer in winter.
Potential to break even in summer perhaps.

And I am guessing there must be companies making/selling some sort of energy storage solutions so you could save your overproduction for times when you have underproduction, no?  If so, is is not cost effective?

Nope, not cost effective, and maintenance hassles. No need for that.

[EEVblog]

Oh, Dave, you should re-position your rooftop antenna.  It will create partial shading and will cause your PV output to reduce. 

No, it doesn't. The support wires were already moved a bit.

[duskglow]

Interestingly, I found this video just a few hours ago.



He created a battery backup system for his house that costs about 700 pounds, and can power everything for eight hours and only the essentials for three days.  I wonder if, connected to a solar system in a clime that works in (the UK isn't, apparently, such a clime) if it could double as a smoother.

[DrGeoff]

Importer in winter.
Potential to break even in summer perhaps.

I'm interested to see what you get during Summer, when the panels themselves cold be at 80-90C. I wonder how much that will restrict their generating capacity over the sunnier months. It may work out the same as the Winter generation.

And I am guessing there must be companies making/selling some sort of energy storage solutions so you could save your overproduction for times when you have underproduction, no?  If so, is is not cost effective?

Nope, not cost effective, and maintenance hassles. No need for that.

Damn right there. Vanadium redox batteries looked promising, but they seemed to have stalled, Otherwise not much really suited to a domestic situation with minimum maintenance and reasonable lifetime.

[EEVblog]

I'm interested to see what you get during Summer, when the panels themselves cold be at 80-90C. I wonder how much that will restrict their generating capacity over the sunnier months. It may work out the same as the Winter generation.

Yes, could very well be the case. More light hours though and higher solar insolation.
I'm approaching 10kWh now in winter on a good day, so expecting a bit more in summer.
We can't break even money wise of course given the rates, but might be able to get close in actual kWh generated/consumed.

[digsys]

Damn right there. Vanadium redox batteries looked promising, but they seemed to have stalled, Otherwise not much really suited to a domestic situation with minimum maintenance and reasonable lifetime. 

I've a few friends with farms, or are greenies, that are completely off-grid. They just buy 2nds in SLAs or even wet-type for next to nothing,
load them onto pallets, add a paint shaker for wet cells (shaken 1hr per day use) and bob's your uncle. Recycled and dirt cheap storage.
A few I know even run their cars / trucks with 2nds. I know it's not for everyone.

[Lightages]

He created a battery backup system for his house that costs about 700 pounds, and can power everything for eight hours and only the essentials for three days.  I wonder if, connected to a solar system in a clime that works in (the UK isn't, apparently, such a clime) if it could double as a smoother.

Sorry to be a bit of a skeptic about his claims for that backup system but he has nowhere hear enough batteries for his claims if he uses energy like most people. Of course he is not like most people.

I have a 48V system with 750AH of capacity.This is enough to run my house for a day. His capacity looks rather much lower, much much lower. He would be lucky to run his house for 3 hours IMHO and the essentials for maybe a day.

[duskglow]

Sorry to be a bit of a skeptic about his claims for that backup system but he has nowhere hear enough batteries for his claims if he uses energy like most people. Of course he is not like most people.

I have a 48V system with 750AH of capacity.This is enough to run my house for a day. His capacity looks rather much lower, much much lower. He would be lucky to run his house for 3 hours IMHO and the essentials for maybe a day.

This guy is rather famous for blowing stuff up with high voltage, so his not being "all there" is kinda somewhat of a very entertaining given.  That said, he did demonstrate that his system works with everything powered up for at least a little while.  So, you're perfectly justified in being a skeptic, but he did demonstrate that it works at least somewhat as advertised, and who knows, maybe that's at least enough to save up some of the excess generated during the day for the night.

[manicdoc]

Hmm, that is crazy. I must admit I have been toying with the idea of getting rid of the mindless controller and hooking it up to something more intelligent. I have an integrated alarm (Comfort) and lights (CBus) via Linux box. Although want to split that function off to a really small form factor dedicated box (PC104); has a database in it, so can't really be a micro controller solution. This could be the straw that convinces me to do it..

The system I designed uses a little PIC18 + 10bT ethernet module I developed that has all the I/O on it and have several of these scattered around the house on a network. They talk to a linux box which has the event handlers and databases and web interface to allow monitoring and control functions. Since I have the Linux server running 24/7 for mail server, dns cache and other things, there was no problem adding the control system to it. It's fairly lightweight in power consumption, just a core-2 processor on a motherboard and a couple of enterprise drives.
This has been running for several years now and I have some nice trend plots of temperature and other measurements that allow me to evaluate aspects of the house design and make improvements where necessary.

Okay, I have structured cabling so easy to drop network where needed. You have peeked my interest - any more details, or would it just be as practical to use one of the off the shelf network to IO boards available now...

[montoyaaguirre]

Thanks for this episode. It was great!

I live in Mexico and it seems to be the Home Solar Power System Paradise.

In Mexico we have a single electricity company and it's run by the government. They don't pay you for the energy you supply to their network. Instead, they only charge you for the difference between the kWh you take from the grid minus the kWh you supply. This means that you don't have to skim on the power consumption during night as long a you produce enough kWh hours during the day. If you supply the same amount of kWh that you consume in a given month you will get an electric bill for $0.00  If you supply more kWh than what you consume each month, you can save it for the next month up until 12 months.
Did I mention that we get 14 Hours of sun daylight in summer and 11 in winter?

Our daily energy consumption is 20kWh during summer and 12kWh during winter. Am I crazy for not having my home solar power system yet?

[DrGeoff]

Okay, I have structured cabling so easy to drop network where needed. You have peeked my interest - any more details, or would it just be as practical to use one of the off the shelf network to IO boards available now...

The modules have 8 digital inputs, 8 digital outputs, 8 1-wire temperature ports and 4 analogue inputs. Separate termination modules are used to add relays, opto-coupling of DI's, conditioning for analogue inputs and termination for 1-wire sensors. There's also a couple of serial ports, again termination modules can be used to turn these into RS232 or RS422 ports. Power is 12VDC and the network connection is 10bT. The Microchip IP stack compiles for it, using a custom BSP and the protocol I use is an encrypted UDP protocol between the Linux server and the remotes. On the Linux server there is a custom event manager that manages the queue of incoming and outgoing events to and from the remotes, and interfaces with the database. The web system interfaces with the database as well.
I can put up some circuits and also have a PCB (100mm x 100mm) for it.

[EEVblog]

I noticed you commented your house doesn't have eaves. That is an unfortunate aspect of contemporary house building in Australia. You could be adding to your A/C load in summer if the walls are radiating heat inside.

Our house isn't bad thermally. Insulation in the walls an roof do a reasonable job.

I'd be interested in just how much you modify your lifestyle to extract maximum benefit. Are you going to be out one day in the sun and thinking "I really should be home doing the dishes"? 

We have a lifestyle that suits this. I work 5 minutes away and come and go a lot. The wife is home 3 days a week. Things like washing can be automated time wise.
Two obvious ones are washing clothes and dishes, both can now be done during daylight hours. And any aircon use can be done during the day too to warm up or cool down for night time.

[ttp]

There's an IR port which moght be interesting to connect to, and I got the meter manual from an online source which has the commands and button sequences. No detail on the interface though, but it is probably fairly rudimentary since the meter reader bloke uses it.

Try to google for IEC62056-21. IEC62056 is a international standard Data exchange for meter reading, tariff and load control, Part 21 - Direct local data exchange.

[madires]

is an example of an absurdly neat US (and apparently canadian too, given by the original file name)

Neat freak here - looks just like mine!  I am proud of my absurdly neat wiring 

When wiring becomes an art :-)

[madires]

Only if you get smart meters. They didn't install those on mine, so it seems they have no way to know my time of day usable to put me on such a scheme.
Smart meters are more popular and possibly mandatory for new installations in VIC?

We didn't have a choice. They were mandatory when the new house was built. I have 3 phases coming in and three smart meters (one includes the ripple control receiver as well). The metering box is on the outside wall and the distribution panel with around 30 RCD's on it is on the inside wall of the garage.

Smartmeters are mandatory too for new houses over here, or if you novate the main distribution panel.

[manicdoc]

Okay, I have structured cabling so easy to drop network where needed. You have peeked my interest - any more details, or would it just be as practical to use one of the off the shelf network to IO boards available now...

The modules have 8 digital inputs, 8 digital outputs, 8 1-wire temperature ports and 4 analogue inputs. Separate termination modules are used to add relays, opto-coupling of DI's, conditioning for analogue inputs and termination for 1-wire sensors. There's also a couple of serial ports, again termination modules can be used to turn these into RS232 or RS422 ports. Power is 12VDC and the network connection is 10bT. The Microchip IP stack compiles for it, using a custom BSP and the protocol I use is an encrypted UDP protocol between the Linux server and the remotes. On the Linux server there is a custom event manager that manages the queue of incoming and outgoing events to and from the remotes, and interfaces with the database. The web system interfaces with the database as well.
I can put up some circuits and also have a PCB (100mm x 100mm) for it.

Hmm, most tempting. What I'm thinking at the moment is:

- Analogue input x 2 for the temperature probes
- Mains switching ouput x1

But within 4 meters of this is a 6 way irrigation controller that could be made controllable from the center. So adding in a 6 way 24v rated switching would cover that. Would be good to also pull in the rain sensor (1 digital input).

I'd really like to get all this controlled from a dedicated small box PC with the Comfort and CBus tie in - currently everything including the kitchen sink is running on the one box (Samba, email, dns cache, web proxy, spam assassin, etc).

[DrGeoff]

Okay, I have structured cabling so easy to drop network where needed. You have peeked my interest - any more details, or would it just be as practical to use one of the off the shelf network to IO boards available now...

The modules have 8 digital inputs, 8 digital outputs, 8 1-wire temperature ports and 4 analogue inputs. Separate termination modules are used to add relays, opto-coupling of DI's, conditioning for analogue inputs and termination for 1-wire sensors. There's also a couple of serial ports, again termination modules can be used to turn these into RS232 or RS422 ports. Power is 12VDC and the network connection is 10bT. The Microchip IP stack compiles for it, using a custom BSP and the protocol I use is an encrypted UDP protocol between the Linux server and the remotes. On the Linux server there is a custom event manager that manages the queue of incoming and outgoing events to and from the remotes, and interfaces with the database. The web system interfaces with the database as well.
I can put up some circuits and also have a PCB (100mm x 100mm) for it.

Hmm, most tempting. What I'm thinking at the moment is:

- Analogue input x 2 for the temperature probes
- Mains switching ouput x1

But within 4 meters of this is a 6 way irrigation controller that could be made controllable from the center. So adding in a 6 way 24v rated switching would cover that. Would be good to also pull in the rain sensor (1 digital input).

I'd really like to get all this controlled from a dedicated small box PC with the Comfort and CBus tie in - currently everything including the kitchen sink is running on the one box (Samba, email, dns cache, web proxy, spam assassin, etc).

The remote I have in the tank room monitors the rainwater water tank levels and also the HWS temperatures, external light sensor and controls a 4-way irrigation system (4 24VAC solenoids on a manifold). The 1-wire DS1820B probles are a very easy option for temperature sensing, which was why I added the 8 1-wire ports to the module. The module itself also has a temperature sensor onboard, so the local temperature can be monitored inside the box. As far as switching loads, that will depend on the relays you end up using. The module outputs are open-collector 1A transistors, which is usually plenty for controlling a relay. The external termination modules are used for this purpose.

That's what I do with the Linux server that runs on the home network. It serves email (with spamassassin), dns caching, local intranet, media server (audio and video), svn repositories, samba drives, databases fro my electronic parts cataloging and BOM system, event management and control/monitoring system. External access is also allowed via SSL with client certs, so when I'm overseas I can check up on things or get access.

[tecman]

Dave:

One note.  The loss of power at higher temps is mainly due to the -2.2mv/c temco of voltage for silicon.  The voltage drops with increasing temps, and thus the power.  Here in NW USA we get max output in winter, but the sun is also at its lowest output for us.

I installed a 9.2 KW system about 18 months ago.  My end cost, after rebates and incentives, was about $ 10K.  To date I have averaged 1 MWH/month.  I did research before finalizing the system.  The Sunny Boy series was limited in the 10 KW range and after looking at other brands I opted of a Fronius.  One item that steered me in that direction was a wider (lower) range of DC input voltage.  This was an advantege in worst case conditions.  I have an ethernet interface that I can monitor the system from any internet connection.

I did the install myself.  It is on a ground mount about 30 meters from the house.  Roof was not big enough and partly shaded by trees.  In out state we have net metering, so overages in production are at the same feed-in rate as usage.  Annual overages are paid out, but I only generate about 60% of my total annual use so I always pay to the utility on an annual basis.

With my system I have had no issue with RFI or harmonic noise.  So far it has all worked very well.

paul
 

[Monkeh]

Fronius

Have you looked into extracting generation data from it without buying one of their stupidly priced converters?

[tecman]

Fronius

Have you looked into extracting generation data from it without buying one of their stupidly priced converters?

I ended up buying one of their converters.  I did, however, get a really good price on it, so I didn't feel too bad.  The data from the inverter is RS485 and the protocol is published.  I could have messed around and cobbled together a ucontroller to read the data, but when I was installing it I did not have the spare time to be messing around with it.  So I bit the bullet.

paul

[Monkeh]

Hmm, got a link to the protocol docs?

Time to get cobbling together.

[Alexei.Polkhanov]

Just generate a waveform that is in phase with and slightly higher voltage than the mains. It's very similar to a synchronous motor drive.

Hmm what happens when one of your neighbors will connect his inverter to mains? He will try to be slightly higher, slightly ahead too. Then they going to race, who is higher?

[tecman]

Just generate a waveform that is in phase with and slightly higher voltage than the mains. It's very similar to a synchronous motor drive.

Hmm what happens when one of your neighbors will connect his inverter to mains? He will try to be slightly higher, slightly ahead too. Then they going to race, who is higher?

You assume (at least in the US) that the grid is a very low impedance system, and small inputs/outputs to the grid will not have any noticable effect on the grid's voltage or frequency.  It would take many 10's of megawatts to move things enough to be seen.

paul

[tecman]

Hmm, got a link to the protocol docs?

Time to get cobbling together.

I do have a manual on the interface that I had downloaded from Fronius, titled "Fronius Interface".  I can not find it on their site, after a quick look, but perhaps if you dig you can find it.

paul

[Alexei.Polkhanov]

You assume (at least in the US) that the grid is a very low impedance system, and small inputs/outputs to the grid will not have any noticable effect on the grid's voltage or frequency.  It would take many 10's of megawatts to move things enough to be seen.

Grid is clustered into small sections. I heard from actual home owners that they had problems when several inverters operate in same area/street for example.

Also all inverters will have to shut off, somehow, automatically when mains are turned off otherwise how utility company going to work on power lines? I am not entirely sure how that "turn-off" feature works, but there have to be something otherwise it is a big problem.

[Leon]

A normal inverter will always shut down operation when the AC signal is lost. Some have an "island" mode in which they can still power the house, but in all cases there will be no AC generated for the outside world.

[Alexei.Polkhanov]

A normal inverter will always shut down operation when the AC signal is lost. Some have an "island" mode in which they can still power the house, but in all cases there will be no AC generated for the outside world.

Yes, obviously it works somehow.  I have done some Googling, I found lot of references to IEEE 1547 which is the standard that describes "distributed" power generation signalling or something like that.

But after looking at 50 PowerPoint decks I am still not sure how exactly does it work in simple case when lets say 2-3 houses have inverters running on same street?  They somehow to turn off when "they do not detect presence of grid". How does your (micro) inverter see difference between AC power supplied by your power company and your neighbor's inverter?

[duskglow]

Interestingly enough, Wikipedia has a pretty thorough treatise on this problem and some solutions.

http://en.wikipedia.org/wiki/Islanding

[mtdoc]

I have a 4500 watt "Grid Interactive" system which means I am grid tied with battery back up so that I have power in case of grid failure - which is not uncommon where I live.

In the US all grid tied or grid interactive inverters must meet UL 1741 anti islanding certification. I'm not sure if  IEEE 1547 is necessary but my inverter meets it as well.

BTW - many people in US areas with unfavorable electricity rate structures (peak, off peak differences etc) use grid interactive systems to allow them to be totally "off grid" during high cost hours and grid tied during low cost hours.

Makes no difference for my system since I pay a straight $0.065 per Kwh am net metered and get an extra $0.18 for my PV production.

[Dreso12]

For PV inverters connected to the grid it is mandatory to have an anti-islanding mode. This works by constantly monitoring voltage and frequency of the grid, if there is a deviation the inverters stop working. The idea is to avoid having hazardous voltages if an area of the grid which is disconnected, for example for maintenance.

Depending on the country the maximum/minimum values varies, but the ranges for voltage and frequency are small, it is necessary as if you have many inverters in one disconnected area of the grid they can feedback each other and continue to work so the ranges have to be small. This is why if you are in a poorly cabled area at the end of the grid you can have problems if many inverters are connected as the voltage can increase over the limits and start connecting/disconnecting.

[IanB]

The idea is to avoid having hazardous voltages if an area of the grid which is disconnected, for example for maintenance.

But workers on power distribution systems also have a responsibility for their own safety. One way to be safer when working on a supposedly isolated system, for example, is to place a short circuit between all the power conductors and ground. Then even if the circuit does become energized somehow, the short circuit current will trip a breaker or fuse.

I wonder if this is the origin of "crowbar" circuits? Perhaps maintenance workers used to lay a real crowbar across the bus bars before embarking on any work?

[EEVblog]

A normal inverter will always shut down operation when the AC signal is lost. Some have an "island" mode in which they can still power the house

Ideally I would have liked that feature, but the grid rarely fails.

[gxti]

Yes, obviously it works somehow.  I have done some Googling, I found lot of references to IEEE 1547 which is the standard that describes "distributed" power generation signalling or something like that.

This bothered me for a long time as well. I have heard elsewhere on this forum that the inverters are biased to "speed up" in frequency unless there is something stronger pushing back. If the main grid goes out, the frequency increases as all the inverters speed up until they trip their over-frequency limit and shut down. A very clever use of positive feedback.

Ideally I would have liked that feature, but the grid rarely fails.

Were I so lucky. My current and previous residence are both across the street from substations, yet the power blips once or twice a month and goes out for over an hour at least once a year, often for no apparent reason. I'm beginning to think I should start avoiding them.

[Stonent]

In this case the solar installation would be providing power to you ate 20c/kWh, rather than into the grid at 6c/kWh so it has its uses, particularly at weekends.

Yeah, use it or sell it cheap.
I pay 21.85 cents + 5 cents green, so 26.85 all day.
Presumably that will not change with the new meters.

Yikes! What is the primary power source for electricity in your area (gas/coal/nuke/wind/hydro)?

The most I've ever paid was about 14.9 cents per KWh and that was the plan they put people on who are considered a high risk (due to credit rating).

I changed companies after my contract was up and got about 4 cents per KWh for a promotion for 3 months and then went up to 5.9 cents for the rest of the year.  The company I was with had a deal where if you give someone your "referral code" you get $50 off your bill and so do they after they make their first payment.  So I shared it on one of those coupon sites and my first bill was $-592.00 and for the majority of the year paid no electric bill.  When I relocated for a new job I had to use the city owned power company and transferred my service and $300 bill credit to my mother in law.

[Stonent]

Since we're on the subject of breaker boxes, here's what a typical US installation looks like:





It's common to have high amperage lines go through a double breaker (such as 2 25amp breakers)

Here's a typical analog meter:



I knew someone once who took a red hot nail and poked a hole in the plastic and would stick a wire inside the gears to stop the meter from working.

Here's more of a typical meter in new installations:



I think there's some sort of IR port on the front where they can just hold a scanner in front to read it in.

[IanB]

Since we're on the subject of breaker boxes, here's what an atypical US installation looks like:

There, fixed that for you 

[DrGeoff]

In this case the solar installation would be providing power to you ate 20c/kWh, rather than into the grid at 6c/kWh so it has its uses, particularly at weekends.

Yeah, use it or sell it cheap.
I pay 21.85 cents + 5 cents green, so 26.85 all day.
Presumably that will not change with the new meters.

Yikes! What is the primary power source for electricity in your area (gas/coal/nuke/wind/hydro)?

The most I've ever paid was about 14.9 cents per KWh and that was the plan they put people on who are considered a high risk (due to credit rating).

Welcome to Horse-trailer, where the energy companies can root your boot however they like.
Peak is 47.7c/kWh curently when 'smart' meters are installed, overall this seems to average to about 25c/kWh. This is about to increase another 1.5% next month. If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times.
Gas prices are also being increased significantly, next month by around 8.5%.

[mtdoc]

I think there's some sort of IR port on the front where they can just hold a scanner in front to read it in.

These are the meters I use to measure my PV production. They have a similar port which is used to program the meter.

[digsys]

If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times. 

I know people who do just that (with the cheap 2nds battery banks). In some cases they are still locked in at the original FIR, so
will never pay for power. It is illegal, and IF you get caught  .... interestingly, it has been suggested as a solution by the providers !!
If they do it, it's legal.

[DrGeoff]

If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times. 

I know people who do just that (with the cheap 2nds battery banks). In some cases they are still locked in at the original FIR, so
will never pay for power. It is illegal, and IF you get caught  .... interestingly, it has been suggested as a solution by the providers !!
If they do it, it's legal.

What part of this could be considered illegal? You are consuming power during off peak times and generating power from the stored energy during peak times. Provided it is installed in accordance with the required standards then it is unliely to be illegal. What is illegal is using the OPHWS feed to pull energy (at around 7c/kWh instead of 11c) for storage and later use.

[Stonent]

Since we're on the subject of breaker boxes, here's what an atypical US installation looks like:

There, fixed that for you 

Atypical because it looks tidy, or atypical for some other reason?

When I moved into my apartment about half of the breakers were labeled incorrectly, good thing I check and recheck before messing around.  I went back with marker and fixed them.

[Stonent]

Welcome to Horse-trailer, where the energy companies can root your boot however they like.
Peak is 47.7c/kWh curently when 'smart' meters are installed, overall this seems to average to about 25c/kWh. This is about to increase another 1.5% next month. If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times.
Gas prices are also being increased significantly, next month by around 8.5%.

Are the electric companies private entities, public, or a mix?

In my state prior to 2002 we had only 1 or 2 private power companies (aside from some cities that had their own plant) and they were regional. The state strictly controlled power pricing. This was called "regulated"  After 2002 the big companies were split into smaller units such as generation and distribution and had to sell power to competing companies and could also buy power from the competing companies.

The state now sets what is called "the price to beat" which is sort of a suggested retail price and competing companies try to sell you on beating that price.

After the industry was deregulated, property owners now own the meter and box on the house. Prior to that they were owned by the power company. The downside is if you have a problem with your meter or wiring outside the house, you have to hire someone to fix it for you rather than have it done for free by the power company.

If you have enough money you can purchase your own electric substation for about $5,000,000 and save significantly on your bill. My former employer purchased one and apparently it paid for itself within the first year.  These substations step down the 150KV coming from the overhead lines to about 14KV and then further down to the various standards in between such as 110, 220, 240, 480, etc.

So with all of this companies can even say you pay xx cents per KWh and we guarantee 25% of it is based on wind or some other "green" technology.  Where your actual power comes from doesn't really change, but your basically making the company buy or generate a certain percentage of power using a "green" technology on your behalf.

Some companies let you pick percentage from none all the way to 100%

[DrGeoff]

If I had a gas supply I'd be looking at one of these ceramic fuel cell generators.
http://www.cfcl.com.au/bluegen/

The size of a fridge and it generates both power and hot water (since it runs at 750C internally) very efficiently 24/7.

[DrGeoff]

Welcome to Horse-trailer, where the energy companies can root your boot however they like.
Peak is 47.7c/kWh curently when 'smart' meters are installed, overall this seems to average to about 25c/kWh. This is about to increase another 1.5% next month. If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times.
Gas prices are also being increased significantly, next month by around 8.5%.

Are the electric companies private entities, public, or a mix?

Depends on the state. Distribution was privatised some time ago, where they buy power off the generating authorities and sell it retail. Now I think the generating assets are being sold off as well in NSW, and have already been privatised in other states. IPART publish the pricing guidelines.

[Stonent]

If I had a gas supply I'd be looking at one of these ceramic fuel cell generators.
http://www.cfcl.com.au/bluegen/

The size of a fridge and it generates both power and hot water (since it runs at 750C internally) very efficiently 24/7.

Yeah I'd like to see the day where it would be common to purchase a house with its own power source, or at least one per city block.

Mr Fusion...when will you get here?

[IanB]

Atypical because it looks tidy, or atypical for some other reason?

It's exceptionally neat and well labeled. I don't think the typical box looks quite as tidy as that.

[(In)Sanity]

I just can't justify going PV yet,  instead I do what I can to cut down on the bill in other ways.  I've been running solar hot water for years,  my hot water heater is turned off at the breaker 3/4 of the year and I have crazy hot water all the time.    My brothers and I did however just put in a 500w solar well for the parents small farm to water some crops that are too far from the main well.   It's amazing how effective it ended up being.   

I have just a 60w panel on the roof at my house that I use for experiments and such,   I use to have this combined with a battery backup unit,  an 80 amp diode (to kill the charging from the UPS),  about 6 8ah batteries and a charge controller.    Once the batteries were fully charged a circuit would kill the power to the battery backup pulling the solar power I collected from the small panel to run a larger device like a PC.  It would continue this cycle several times a day.   This of course would quickly destroy the batteries due to the frequent cycles.   Perhaps I should try it again with some super capacitors,  or a very large deep cycle battery bank.

Jeff

[GeoffS]

I've friends nearby who are about to make a decision on solar so I've pointed them at the video.

As far as tariff go, I  have three separate meters, all on separate tariffs plus another meter for the 3 phase supply to the shed.
All local power is hydro generated and was cheap until some bright spark in government decided we should be on an equal footing with other states. We export more power than we consume.

Here's a photo of the main meter box.

[Ed.Kloonk]

Atypical because it looks tidy, or atypical for some other reason?

It's exceptionally neat and well labeled. I don't think the typical box looks quite as tidy as that.

I agree. It looks pleasing.

The only thing I got apprehensions about was I wondered if they are Quicklag breakers. I hate Quicklag. They're an expensive breaker here, for no apparent reason either.

I always cringe when I have to replace a faulty one or add one in to an existing box. $$$$$$   

[EEVblog]

I got that drop just after 2pm again today, so must be shading form the nearby houses and/or trees with the low sun angle in winter.
Will have to do another roof timelapse to capture what's happening.

[Pat Pending]

http://spacestationlive.nasa.gov/displays/spartanDisplay1.html

Of out curiosity, this link to the ISS live data feed displays the power output from each of the panels on the station.
On the 2nd info page it shows that they are using ammonia cooling.

[digsys]

What part of this could be considered illegal? You are consuming power during off peak times and generating power from the stored energy during peak times. Provided it is installed in accordance with the required standards then it is unliely to be illegal. What is illegal is using the OPHWS feed to pull energy (at around 7c/kWh instead of 11c) for storage and later use. 

It is illegal to use "cheap" power to charge up a battery (or other storage bank) - then resell it back to them at peak time.
Note: This is on viable if your FIR is much greater than the "cheap" rate. Ring them up and say you're doing it :-)
It's NOT the same as "selling" solar-power or excess EV storage (IF that ever becomes feasible)

[DrGeoff]

What part of this could be considered illegal? You are consuming power during off peak times and generating power from the stored energy during peak times. Provided it is installed in accordance with the required standards then it is unliely to be illegal. What is illegal is using the OPHWS feed to pull energy (at around 7c/kWh instead of 11c) for storage and later use. 

It is illegal to use "cheap" power to charge up a battery (or other storage bank) - then resell it back to them at peak time.
Note: This is on viable if your FIR is much greater than the "cheap" rate. Ring them up and say you're doing it :-)
It's NOT the same as "selling" solar-power or excess EV storage (IF that ever becomes feasible)

I wasn't suggesting selling the power, but making use of the stored power during times when the peak rate is expensive. It would not be viable to sell the power anyway, since the off peak rate is still higher than the feed-in tarrif in NSW. You would end up losing money.

[N TYPE]

As an electrician I have to say that having the customer standing watching you work is the worst..
Let alone having the home owner filming you while you work and blogging about it.. Nightmare

[BillyD]

As an electrician I have to say that having the customer standing watching you work is the worst..
Let alone having the home owner filming you while you work and blogging about it.. Nightmare

True! Reminds me of a notice in my local garage:

Our rates are:

• €10 per hour
• €20 per hour if you watch
• €50 per hour if you already tried to fix it yourself and made it worse

[madires]

Since we're on the subject of breaker boxes, here's what a typical US installation looks like:

Another piece of art :-) It's amazing how the installations differ across countries.

[digsys]

I DID misread your first comment, but for clarification - There are many people still locked into the "original" FIR, which was extremely generous!
As I said, they charge up their "storage banks" during off-peak, then "sell" the same energy back at peak-time. That is illegal.

If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times. 

I know people who do just that (with the cheap 2nds battery banks). In some cases they are still locked in at the original FIR, so
will never pay for power. It is illegal, and IF you get caught ...

In many cases, it is also - either illegal or breach of contract to store off-peak rate energy and USE it during peak times.
Their pricing model depends on these tariffs periods. The supply companies ARE working on large scale pilots to do just that, and we'll all
pay for that as well ! I am involved with various organisations that have been investigating storage solutions. As all this is new -
there are all sorts of deals / contracts / trials going on, even in a single supply area. It's a bit of a mess.

I wasn't suggesting selling the power, but making use of the stored power during times when the peak rate is expensive. It would not be viable to sell the power anyway, since the off peak rate is still higher than the feed-in tarrif in NSW. You would end up losing money. 

As I said - that is NOT allowed in many contracts, but pressure from consumer groups and the public is driving it in all directions.
You'd be shocked at the FIRST draft of the rules and regulations when smart meters were first proposed. Unfortunately, protected by a strict NDA.

[madires]

True! Reminds me of a notice in my local garage:

Our rates are:

• €10 per hour
• €20 per hour if you watch
• €50 per hour if you already tried to fix it yourself and made it worse

ROTFL :-) Let me add another two (based on my personal experience :-):

• €200 per hour if two of your employees tried to fix the problem for a week or two but haven't got any clue.
• €500 per hour, as before, if I'm able to fix the problem within 2 hours.

[Towger]

True! Reminds me of a notice in my local garage:

Our rates are:

• €10 per hour
• €20 per hour if you watch
• €50 per hour if you already tried to fix it yourself and made it worse

Were is this '€10 per hour' garage?

[SeanB]

Under a shade tree just outside the city limits by me. He does a roaring trade in fixing broken exhausts using only wire and old cans.

[Bored@Work]

As an electrician I have to say that having the customer standing watching you work is the worst..

As a customer I have to say that watching electricians work is an absolute must. Don't get me started  ...

[duskglow]

I must confess I love watching tradespeople work.  I try my best to be unobtrusive and even helpful, but I learn so much, and I find by engaging them in conversation and being friendly they generally don't mind - or at least I avoid pissing them off to the point where they tell me to get lost.  I think they can tell the difference between genuine interest and just trying to make sure they don't screw up.

And, every now and then, you do catch a mistake.  I did once, saving a company quite a bit of money.  And, as long as you approach it in the right manner ("hey, I just noticed this, I know I'm not an expert, but are you sure this is right?") I find 99% of the time they're grateful you caught it.

It's all in how you approach it.  Treat them like a human and they'll return the favor.

[Leon]

A normal inverter will always shut down operation when the AC signal is lost. Some have an "island" mode in which they can still power the house

Ideally I would have liked that feature, but the grid rarely fails.

This is not meant for grid failure (although it could work that way), it's a feature to maximize the amount of solar energy you can use. It's a way to store the energy you generate during the day and use it in the evening/night. See fi: http://powerrouter.com/products/powerrouter-solar-battery-self-use
SMA has similar options. In countries like Germany (>23GW peak PV output) the electricity price on the spot market can be negative during the day. Meaning you actually have to pay to get rid of it. Storing the energy and using it later on can be a worthwhile action. And it's not illegal: it's your PV system, and it's your energy. You just don't sell it to your utility company for a low rate.

[hpnut]

This is not meant for grid failure (although it could work that way), it's a feature to maximize the amount of solar energy you can use. It's a way to store the energy you generate during the day and use it in the evening/night. See fi: http://powerrouter.com/products/powerrouter-solar-battery-self-use
SMA has similar options. In countries like Germany (>23GW peak PV output) the electricity price on the spot market can be negative during the day. Meaning you actually have to pay to get rid of it. Storing the energy and using it later on can be a worthwhile action. And it's not illegal: it's your PV system, and it's your energy. You just don't sell it to your utility company for a low rate.
[/quote]

Hello Leon,

what SMA device is this?  I am interested.

thank you.

hpnut in Malaysia

[moemoe]

ripple control, wth is that for?

Ripple control, such a rude word, here in germany we call that "Rundsteuertechnik", can't really think of an exact translation, but somehow like group/round control technology. I think, to be exact, ripple control is only one form of Rundsteuertechnik, but the most used here, a signal gets modulated onto the mains AC.

I also took some pictures of the power distribution here, the first is in the staircase for the two flats on this floor. The left one still has the old installation with these big clunky D fuses.
The left meter has two scales for day and night, in the middle you can see the ripple control reciever to switch between the scales together with its contactor.

(Our) right meter has only one scale, because after tracking the power usage for some time I found out that we don't use that much power at night, so we can't save any money using day/night tariff.

The following two pictures are our in flat fuse box, we only have 3 rooms and 60m², so it's quiet a lot in there. You can nicely see the color coded labels indicating the residual-current circuit breaker they are attached to. One nice detail is "F 1", this is the light in the corridor that is not RCCB protected, so you can always find your way to the fuse box

The two three-phase switches are for the oven in the kitchen and the storage water heater, blue is for the rooms with water (kitchen and bathroom), yellow for the dry rooms. The electricity in our flat got renewed just before we moved in here about 5 years ago.

You can also see the odd-value B13 fuses, they used to have 1,5mm² rated for 16A, but then changed the norm so that they are only allowed to carry 13A anymore, and they didn't want to rip out all old cables. But we also got some new 2,5mm² cables fused with B16s.

[Rodville]

I can't find where the time lapse video is. Can someone please link me/

[Leon]

Hello Leon,

what SMA device is this?  I am interested.

thank you.

hpnut in Malaysia

It's a special version of the Sunny Island series: http://www.sma.de/produkte/batterie-wechselrichter/sunny-island-60h.html

[Alana]

How long does it take for such system like Dave has to pay for itself?

ripple control, wth is that for?

Ripple control, such a rude word, here in germany we call that "Rundsteuertechnik", can't really think of an exact translation, but somehow like group/round control technology. I think, to be exact, ripple control is only one form of Rundsteuertechnik, but the most used here, a signal gets modulated onto the mains AC.

I think its similar to what i know as SCA [sterowanie czestotliwoscia akustyczna - audio frequency control]. Basically its injecting audio frequency signal 216Hz into power lines at substation and that controls electronic switches for on-peak/off-peak rates, street lights and other things like that. I helped to build one transmitter unit back in 2000 as my job experience as electronics technician and if someone is interested i think i can still find some of my notes on the subject.

[tecman]

Dave:

You should talk to SMA down under and see if they will give you an inverter to tear down.

Here is what my Fronius looks like with its cloths off.  There is a DC-DC stage to stabilize the DC into the inverter stage for optimization.  There are three inverter sections which are switched on as a function of power delivered.  They rotate which inverter section comes on to wear level them.

paul

[mickpah]

Hi Dave,
I know I'm falling for TI markieting, but this was just so tempting to play with.
An MPS430 launch pad and a CC3000 wifi booster pack for $40 USD delivered. Fedex included in the price and here for me to play with in  3 days !.

https://estore.ti.com/msp-exp430g2-cc3000boost.aspx

Just the thing to send your generated power reading up to the sever without burning up all your sun powered goodness 

[WattSekunde]

Hi Dave,
back in 2008 we installed 7.35 kWp with 42 modules (175 W Schüco SPV 175 SMC-1) and two SMA 4000TL (Schüco branded) wired with 6mm^2. The whole system works fine since end of 2008 here in Germany.
From december 2008 to now ;-) we selling a total of 33273 kWh.
We decided to install 4 strings 2x(10+11) divided to both 4000TL. Now we are able to compare both SMAs and the 10 and 11 strings against each other.
WR1: 16672 kWh
WR2: 16601 kWh

Little 4000TL teardown in my attachments:

[EEVblog]

Huge array, very nice! 
I'm a tight arse, so only got a $5K 3kW system. But realistically, 3kW is pretty much all we needed to offset our daytime use. At 6 cents FIT I didn't think it was worth installing a bigger system.

[WattSekunde]

Thanks 

We build a "Passivhaus" (http://en.wikipedia.org/wiki/Passive_house). That means we need around 7000kWh / year at all. That includes heating and hot water. We don't need gas or oil. Only electricity and water ;-). So our solar power system delivers nearly the same we need. The power net is our buffer. Maybe in future we need to add batteries .

[dr.diesel]

Maybe in future we need to add batteries .

You my friend are hard core, a feat I hope to someday achieve.

[GeoffS]

It would be interesting to see how much power you generate today, it being the shortest day of the year.

[hpnut]

Huge array, very nice! 
I'm a tight arse, so only got a $5K 3kW system. But realistically, 3kW is pretty much all we needed to offset our daytime use. At 6 cents FIT I didn't think it was worth installing a bigger system.

Dave, my 2.5kW system costs AUD11,000 equivalent but the Malaysian FiT payment is more generous at 42 cents.  I get two sets of bills every month: consumption bill which I have to pay my utility provider and also a generation advice which the same utility provider credits to my account.

hpnut in Malaysia

[EEVblog]

It would be interesting to see how much power you generate today, it being the shortest day of the year.

It's also overcast.
Based on two good days so far, it is clear that minimum the 3KW system will deliver on a good clear clear winters day is over 9kWh.
A heavily overcast day still seems to give at least 6kWh.
I expected a fair bit less, so am quite happy with that.

[Eight8]

Huge array, very nice! 
I'm a tight arse, so only got a $5K 3kW system. But realistically, 3kW is pretty much all we needed to offset our daytime use. At 6 cents FIT I didn't think it was worth installing a bigger system.

I was able to secure the 0.44c FIT in QLD. Consequently we installed the maximum size inverter allowed, a Xantrex 5kW. We added to that 6kW of solar panels. Most of the time we never hit the inverters maximum, however on a cool sunny day we can hit the limit. To get the most from the panels you need full sun and a cool breeze to prevent them derating due to temperature.

[Bored@Work]

It would be interesting to see how much power you generate today, it being the shortest day of the year.

It is the longest day of the year, you just have to be on the right half of the earth

[WattSekunde]

Maybe in future we need to add batteries .

You my friend are hard core, a feat I hope to someday achieve.

Thanks. We try our best. 

[elektrinis]

Hey Dave. I may have a money-saving solution for you. Sorry I did not read all 12 pages and it may have been suggested already.
What I am suggesting is to add a buffer battery. Not a crappy lead acid one, but today's quality lithium one. These (sinopoly LiFePO4 for example) are quite cheap and hold thousands of full cycles or tens of years of calendar life. And they have no capacity loss (Peukert's effect), are very safe, etc (those are used on some electric cars, but especially in power grid, large (multiple MWh sized) UPSes, etc).

Battery management and integration is the tricky part, but here I have another solution. My company is producing battery management system (BMS) for lithium batteries, which is well integrated with SMA converters. Our BMS is very popular in Germany and other solarized countries. Check it out:
http://www.elektromotus.lt/en/products/battery-management-system-bms
http://www.elektromotus.lt/wiki/index.php?title=Main_Page&Itemid=155

[hpnut]

Hello all.  This is continuation of the 2.5kWp system installed at my home. 

Today was Testing & Commissioning day by my utility provider Tenaga Nasional.  System was successfully commissioned  at 1100h.  It was raining and we had overcast cloud too, until around 1600h.  At 1900h sundown, the panels stopped production.  Total production was 6kWh and 5kWh exported.  Here are some photos.

Arjunaidi from Putrajaya, Malaysia

[hpnut]

more photos

[hpnut]

I also installed a Sunny Boy WebBox to view inverter performance data.

[timelessbeing]

Great video, Dave. Have you calculated how long it will take to break even on your investment?

I wonder why the installer didn't adjust the height of the rails on the brackets to offset the "undulating" roof structure.  I know in the end it doesn't really matter... but the brackets have elongated holes, why not use them to make the rails straight?

or take it a step further, and tilt the panels towards noon-day sun position. The angle of incidence to the sun affects output does it not?

Why are PV panels connected in series rather than parallel? Is it because the higher voltage reduces losses? You can use cheaper, thinner conductors? It's going to increase the costs of components in the inverter though right?

[mtdoc]

Why are PV panels connected in series rather than parallel? Is it because the higher voltage reduces losses? You can use cheaper, thinner conductors?

Yes, less losses and because voltage needs to be well above utility voltage for mppt conversion before inverting. Typical individual panel Vmp is about 30V

It's going to increase the costs of components in the inverter though right?

No, more volts means less amps= less copper= less money.

[timelessbeing]

No, more volts means less amps= less copper= less money.

I was thinking higher voltage rated caps, transistors etc.. but maybe it's insignificant compared to copper costs.

[SeanB]

600V caps are about the same price as 400v units, basically the same construction just a thicker oxide layer grown on the surface. The transistors in any case will be 1000V or 1200V units, so no cost difference. Copper losses will be the same, but the thinner wire used costs less, and the thinner board copper is cheaper and means you can have narrow traces on the same board as broad power traces.

[mtdoc]

It's not the copper or losses in the electronics that's the issue.  It's the DC voltage drop in the wire run from panels to inverter or charge controller if battery based system. You generally want less than a 2% voltage drop from array to inverter or controller. This can mean fat, expensive wire.

If the PV is on the homes roof then the wire run may be a short wire run and it's not as much of an issue. But if the house is large enough so that the PV array is quite a ways from the electronics or if the array is on a ground or pole mount away from the home - this becomes a major consideration.

It's a bigger  issue for battery based systems (off grid or grid tied with battery back up).  The charge controller generally have lower max input voltages and you don't want the individual string voltages too far above battery bank voltage (12, 24 or 48V nominal) for mppt conversion efficiency sake.

[starchild]

Hi chaps.

I haven't read anything here about deploying micro inverters instead of a string inverter.

I use a lot of home automation and am really interested in using every last bit of power from an installed PV system and not allowing it back to the grid - the intelligence that I can build into my HA brain will hopefully help me do that. However I want to get very granular data to model what's going on and the data extracted from each individual panel by way of these micro inverters is what I need. It will of course add to the installation cost but there is also a saving by way of increased panel efficiency as the effect of shading will be reduced - and I'll get a considerably longer life than I would from the string inverter. Cabling and switchgear is also simplified as it's plain old mains voltage.

Anybody investigated the pro's and con's and got any real world experience?

I've only found two manufacturers and I'm limited to one of them, Enecsys, as the other (Enphase) uses power line communication which is very likely to cause issues as I employ X10 as my automation protocol on the mains wiring.

I'd love to store any excess energy and use it in the evening but battery storage is way too expensive - and those cells don't have a very long life expectancy!

[DrGeoff]

With some new and interesting technology in the supercap area, it would be interesting to see if using a supercap behind each panel to store charge and make it available to the inverter when the panel is dark would be an interesting power storage mechanism.

[DrGeoff]

Dave,

Any updates on the efficiency or power measurements after a while of using it? Particularly after the few hot days we've had?

[bronzies]

I really enjoyed this video, i think videos that cover the really practical aspects of electric circuits like PVs and stuff come second only to the tear downs of good mobile gadgets like the nook teardown (that was my absolute favorite! especially the part about the "magic" light scattering. so funny to listen to an electronics engineer talk about materials engineered to scatter light or something else non-electricy!) please keep em' coming!

[jnissen]

Looks like September 18th was the last communication with the PVOutput web site. Perhaps Dave pulled the plug on the communication or he has not checked it lately? Are you using another monitoring system now?