EEVblog #724 - Home Solar Power System Analysis & Update

[EEVblog]

Dave looks at his 3kW home solar power system after being in operation for 18 months and analyses the results.
How much energy was produced?
How does net and gross metering work?
What is the payback period?
What is solar insolation?
The 3kW system uses 12 x 250W LG MonoX panels
http://www.solarclarity.nl/wp-content/uploads/2011/09/Data-Sheet-LG-Mono-and-Multi-X-ENG.pdf
and an SMA Sunnyboy 3000TL inverter.
http://files.sma.de/dl/15330/SB5000TL-21-DAU131211W.pdf
Uploading data to PVoutput.org using PVbeancounter and bluetooth from the Sunnyboy inverter.

[nixfu]

Dave...side question.  What is the aerial mast for?  Do you need to raise your TV antenna that high in the area you live?  Or is it used to capture the lightning you need for the 1.21 gigawatts to power your flux capacitor?

Glad you covered what kind of AC you use.  I imagine that is a large percentage of your energy cost being in Sydney.

[tecman]

Here in USA-USA-USA I installed a 9.2 KW rated system, that is just over 3 years since the install.  I am in PA which is in the northeast.  I generate 12 MWH/year.  That accounts for 60% of our total usage.  Nice thing is we have net-metering which has unity pay for use-sell back (approx $0.13/KWH at this time).  It uses just one meter which subtracts the solar excess generation from the used power.  We have little to negative usage from May through October, and consume the most power over winter.  Gray days, snow covered panels and heating costs (geo-thermal heat pumps) are the cause of the greater winter usage.  This winter was very cold (last month average temp was 22 deg F !).  I had to go out and clean snow off the panels several times.  It is a ground array, so cleaning is easy, but several times I was unable to get to the panels and had to wait for improved conditions to clean off the panels.

Paul

[EEVblog]

Dave...side question.  What is the aerial mast for?  Do you need to raise your TV antenna that high in the area you live?

I live in the Hills District and I'm down the bottom of a gully...
Although the mast came with the house, so I'm not sure if it's 100% necessary in my case.

[EEVblog]

I had to go out and clean snow off the panels several times.

Snow? What's that? I don't understand...

[nixfu]

Have you thought of adding battery storage?  It seems it would pay for itself based on how little you get for net-metering credit. 

[Kohanbash]

Hi
Nice video.

- You can get a pyronometer for about $200 (at least in the US) with an analog output.
Ex. http://www.apogeeinstruments.com/pyranometer-sp-110/

tecman- I am also in PA (Pittsburgh) I am surprised how much you generate. In Pittsburgh we only have about 60 sunny days a year. How large is the area of your system?

Cheers!

[LaurenceW]

Dave, here in the "Old Dart" (wtf?), I have a 4kWpk system. We are further from the equator that you are, so longer summer days mean I am able to beat your figures for 2 (maybe 3) months of the year, in high summer. But you've got me beat, the rest! Check out how much your solar power waxes and waynes through the seasons, and compare it to mine (PVoutput user Wilkins_watts). Very low power in the short, cold winter days!

Like you, I went for a premium system of Sanyo/Panasoinc panels and SMA TL4000 inverter. It just all works. The system has been in 3 1/2 years. I paid TOP DOLLAR (about USD $16000 equivalent - ouch, yes), as did many other "early adopters." Yes we, too, saw something of a GOLD RUSH, until the government turned down the Feed In Tariff scheme, somewhat. Still, my system will also pay for itself in around 6 years, then I can sit back and enjoy the overly generous gov't susbsidy, which continues for a further 18 years after break even WOOOOOO-HOOOOO.

Most Brits move house, on average every seven years. There are just over 500,000 solar PV systems in the UK. When doing the payback calcs, a major and hard-to-quantify factor in all calculations is "how does the housing market value a solar installation?" The jury is still out on that one in the UK, but I think attitudes are changing, as people slowly "get it".

There is another side benefit, of course, in that it makes you THINK about every kWhr! "The cheapest KWhr is the one you never burned."

[EEVblog]

Have you thought of adding battery storage?  It seems it would pay for itself based on how little you get for net-metering credit.

Thought about it, but not really looked into it. We have limited space to put such a system.

[EEVblog]

Dave, here in the "Old Dart" (wtf?), I have a 4kWpk system. We are further from the equator that you are, so longer summer days mean I am able to beat your figures for 2 (maybe 3) months of the year, in high summer. But you've got me beat, the rest! Check out how much your solar power waxes and waynes through the seasons, and compare it to mine (PVoutput user Wilkins_watts). Very low power in the short, cold winter days!

Our system does not have ideal tilt or angle. It is what it is unfortunately.
Our solar insolation would be higher than the old dart, so if conditions were the same ours would produce more.

[EEVblog]

How large is the area of your system?

No idea. You can read the panel datasheet and calculate.

[rs20]

I had to go out and clean snow off the panels several times.

Why not put heaters under the panels, and melt the snow away? #SolarRoadways

[dr.diesel]

Damn!  Here in Indiana I pay $0.09/kWh USD.  (Pricing is tiered, but my average)

[number33]

Just to rub salt in the wound, the UK system isn't a net or a gross method, it pays a FIT for every kWhr generated regardless of whether or not you use it and then an additional amount for each kWhr exported to the grid.  It's currently 13.9p (26.7 Aus cents) per kWhr generated plus 4.9p (9.2 Aus cent) per kWhr exported.  This is for domestic (<4kW) installations.

Early adopters get an even better deal, just from memory something like 43p/kWhr generated plus 3p/kWhr exported and fixed for 25 years.  Of course they did pay much more for their installations, perhaps two to three times the current rate. Payback times were about ten years then and are probably about the same now.

[tecman]

I had to go out and clean snow off the panels several times.

Snow? What's that? I don't understand...

You don't know what you are missing !

[tecman]

I had to go out and clean snow off the panels several times.

Why not put heaters under the panels, and melt the snow away? #SolarRoadways

An area  20m long by 3.5m would require a major investment for heaters an the power to run them.  It also would need to work in the teens (F) to help.

paul

[tecman]

tecman- I am also in PA (Pittsburgh) I am surprised how much you generate. In Pittsburgh we only have about 60 sunny days a year. How large is the area of your system?

Cheers!

I have 40 panels, nameplate rating is 9.2 kw.

I generate almost exactly what PVWatts indicated.

paul

[rs20]

An area  20m long by 3.5m would require a major investment for heaters an the power to run them.  It also would need to work in the teens (F) to help.

paul

It wouldn't require a major investment on the power to run the heaters; the solar panels make their own electricity for free! #SolarRoadways

[ Edit: Just to be clear, #SolarRoadways is synonymous with #Joke  ]

[KTP]

I love those Mono-X panels.  I just put four 270 watt LG panels on our homebuilt truck camper and am already seeing over 600 watts flat mounted during March in Seattle.  I am using a Midnite Classic 150 since their factory and engineers are about 20 miles from me.

[EEVblog]

I love those Mono-X panels.  I just put four 270 watt LG panels on our homebuilt truck camper and am already seeing over 600 watts flat mounted during March in Seattle.

Nice. I assume you have storage in that?

[rolycat]

My PV installation is curiously similar to Dave's - 12 LG MonoX panels and an SMA Sunny Boy inverter.

The main difference is that the panels are the 300W NeON type giving a 3.6kWp system. These were chosen due to limited roof space.

It was installed in November 2014 and generation so far has been very good, generally outperforming expectations each month based on a projected annual output of 3,337 kWh. Predicted payback time should be around six to seven years.

(EDIT)
Maximum observed output so far was 3,513W on 25th February. It seems improbably high for the middle of winter - awaiting summer figures with interest.

[jolshefsky]

For what it's worth, I wrote a blog about my own solar system. I'm in upstate New York, U.S. (the western part of the state at around 43°N latitude).

My system was a lot lot more per watt installed—perhaps Dave did a lot of the work himself. Subsidies and tax rebates brought the cost down to reasonable levels, my payback is much longer—more like 20 years. Checking my work, our net metering works differently where I'm at (it's more like a virtual "energy bank" which I feed excess into the grid and draw from it until it's gone each year) my system produces around 4,000 KWh/year for around US$600/year (at US$0.15/KWh) which is around double the $363 figure I got ... hmm ... I better check my work there.

[reagle]

Dave, loved the timelapse. What material is your roof made of- is that metal tiles? It looked like they just sit in place with no mounting?!

What a coincidence- my system  is also an Upstate NY system. (See the year end update on it  in http://kuzyatech.com/solar-a-year-later)
It's 22 Sunpower ACPV panels rated 5.5kW total, but only managed around 4.3kWh last year. Too much damn snow with my low slope roof.
This year will be even worse- my microinverters were not talking for 39 days in a row due to three feet of snow on top of the panels!
I fought with it for a bit, but then ran the numbers and realized I better spend the energy digging out my driveway vs clearing the panels on the roof
It's now mid March, and I still have a few panels slowly defrosting.
On a positive note, getting data from it is very nice- each microinverter talks to a central gateway over powerline link, and that talks to the net. So I get individual panel stats

[EEVblog]

Dave, loved the timelapse. What material is your roof made of- is that metal tiles? It looked like they just sit in place with no mounting?!

Terracotta.
Every 2nd row has a nail to hold down, so can remove the other rows.

[Poe]

I've never had any money to invest, so maybe I'm way off base here.....
But I get the impression that it would make more financial sense to invest that $5k in the stock market.
Eight years of compounding savings versus just getting your money back (Does this equipment retain its value on the second-hand market or would people be silly to buy used?) then hoping you can turn a profit near the end or after the warranty has expired.
Dunno.  Just thinking out loud.

[NiHaoMike]

How about use a Raspberry Pi as a controller to try to make the best use of the energy during the day?

[EEVblog]

I've never had any money to invest, so maybe I'm way off base here.....
But I get the impression that it would make more financial sense to invest that $5k in the stock market.

Stock market is not guaranteed, it can easily go down. It is in fact a gamble, a solar system is the opposite of that. Also, $5K in the stock market isn't much in terms or return if you are talking dividends and spreading your risk.
A solar system will last 20+ years (ok, maybe not the inverter), so if you pay it off in say 5 years, that leaves 15-20 years of returns. If you think energy prices will ever go down by any significant amount, you are kidding yourself.
If I used all the energy I produced I'd save approx $1300 per year (based on 15kWh/day) after the payback period. That is about 25% per year return on that $5k investment, practically guaranteed. That beats the share market any day.

[EEVblog]

How about use a Raspberry Pi as a controller to try to make the best use of the energy during the day?

Huh?
How?

[Someone]

How about use a Raspberry Pi as a controller to try to make the best use of the energy during the day?

Huh?
How?

You'd need to interface it to several of your high consumption appliances and then it would decide based on your net export when its best to start using power. The 4 obvious appliances:

• Storage hot water tank, run with a high temperature cutoff higher than the standard thermostat (would require a tempering valve to keep the output temperature safe)
• Heat pumps, heat/cool your house a few degrees beyond your target when power is cheap, the insulation will keep it comfortable.
• Freezer, ideally with a fan forced fridge to use the stored energy as the food in the fridge won't tolerate temperature cycling like the frozen food will.
• Washing machine, rather than a start timer the intelligent controller will start at the best time

Smart meter uptake was supposed to drive the availability of "smart" appliances that would have these sorts of features built in, but the in home displays are hard enough to purchase/install let alone something complex like a controlled load.

[pickle9000]

I've never had any money to invest, so maybe I'm way off base here.....
But I get the impression that it would make more financial sense to invest that $5k in the stock market.

Stock market is not guaranteed, it can easily go down. It is in fact a gamble, a solar system is the opposite of that. Also, $5K in the stock market isn't much in terms or return if you are talking dividends and spreading your risk.
A solar system will last 20+ years (ok, maybe not the inverter), so if you pay it off in say 5 years, that leaves 15-20 years of returns. If you think energy prices will ever go down by any significant amount, you are kidding yourself.
If I used all the energy I produced I'd save approx $1300 per year (based on 15kWh/day) after the payback period. That is about 25% per year return on that $5k investment, practically guaranteed. That beats the share market any day.

Has it decreased the value of your home? My guess, no. It has increased its value, it's a visible feature.   

[SodaAnt]

Damn!  Here in Indiana I pay $0.09/kWh USD.  (Pricing is tiered, but my average)

Here in Seattle I often average $0.05/kWh USD. Combined with the very general lack of sunlight here, its a horrible economic proposition.

[mtdoc]

Here in Seattle I often average $0.05/kWh USD. Combined with the very general lack of sunlight here, its a horrible economic proposition.

Not true. You just need a bigger array. Because solar panels have gotten so cheap, you can get twice the array at 1/4 of what it would have cost just 5 years ago. And WA has an incentive program that pays you beyond what you save on the price of power from your utility. If any of your equipment ismade in WA you get paid even more. Because my inverter is WA made, i get paid $0.18 per kWh in addition to the $0.07/kWh I save. If your panels and inverter are WA made then you get $0.54/kWh! Unfotunately there is only 1 company making panels in WA and they are expensive.

[EEVblog]

You'd need to interface it to several of your high consumption appliances and then it would decide based on your net export when its best to start using power. The 4 obvious appliances:

• Storage hot water tank, run with a high temperature cutoff higher than the standard thermostat (would require a tempering valve to keep the output temperature safe)

I have gas hot water

• Heat pumps, heat/cool your house a few degrees beyond your target when power is cheap, the insulation will keep it comfortable.

We don't have heat pumps in Oz, we have aircons, and I already mentioned I do this when required (not often)

• Freezer, ideally with a fan forced fridge to use the stored energy as the food in the fridge won't tolerate temperature cycling like the frozen food will.

We don't have a dedicated freezer.

• Washing machine, rather than a start timer the intelligent controller will start at the best time

Already said we do this, washer and dishwasher. It already has a timer, or we simply turn on manually.

Basically, there is nothing we can "automate" that would save anything.

[EEVblog]

Has it decreased the value of your home? My guess, no. It has increased its value, it's a visible feature.

Correct, it adds value, likely much more than the cost, gotta love psychology.
It won't be long before houses without solar will be frowned upon a little by buyers, if it's not happening already.

[EEVblog]

Yeah. But so is a pool a feature but it doesn't appeal to all buyers.

I suspect very few people would look negatively upon a solar system.

Hence it may not add value if the buyer would pay to fill it in.

Who would get rid of a functioning solar power system?

A solar system is unlikely to factor greatly either way given it's relatively small value. House prices are governed by more immutable things like position, land size, schools, transport and so on.

Of course, but it's all part of the psychology. I've been to auctions were people are swayed to bid first because they can win a free bottle of plonk. Or get excited at an open home because it has a kind of tap they like. Or walk out of a rental apartment investment because it has some gyprock cracks etc.
Humans are generally not that rational and calculating, they are emotional creatures.

[pickle9000]

Has it decreased the value of your home? My guess, no. It has increased its value, it's a visible feature.

Yeah. But so is a pool a feature but it doesn't appeal to all buyers. Hence it may not add value if the buyer would pay to fill it in. A solar system is unlikely to factor greatly either way given it's relatively small value. House prices are governed by more immutable things like position, land size, schools, transport and so on.

The economics make my head hurt but I think early adopters are as likely to be motivated by environmental concerns as they are by the economics of a solar system. They would also have gotten stung by the reduction in the feed-in tariff ( at least in Victoria) so whether it was better to invest the money in the stock market or paying down the mortgage is not clear cut.

In Canada the money is better spent on insulation. In fact insulation is a big selling feature. True location and all the others are bigger but anything that reduces monthly expenses and does not hurt your (or your neighbors) property value is good. If it also helps with the environment and you are in favor of that then why not.

Even purely cosmetic things offer little to the value of the home but I keep my grass cut and have nice landscaping. I like the way it looks, I enjoy my home.

[johnh]

Here is article on the age  website (newspaper)  about a family in Melbourne who installed a 3.6kw solar power system and a 16kw battery system that can be used when energy from the grid is at its most expensive.

http://www.theage.com.au/victoria/solar-to-power-every-second-home-in-victoria-20150118-12srdt.html

[mux]

Couple of interesting points. First of all, my 2kWp system (brand new, Netherlands) at €1300 investment pays back for itself in like... 4 years? We have one-to-one payback. With second hand (unused but older) German panels you can get down to 2.5y payback period. That is batshit crazy; it means that even when lightning strikes and completely destroys your uninsured PV system after 10 years, you'd still have had a couple hundred percent ROI. With the average system lifetime being about 19 years around here (and rising, because newer systems are generally much more reliable than the early-2000s systems), there is zero financial reason not to install solar panels. Better still, the government has promised not to decrease FIT in the next 3 years. You'd either have to have objections against the aesthetics or an extremely unfavourable roof orientation/shadow casting to not install solar panels here.

Of course, things are quite different abroad. I'm amazed at your 7.5y payback period even at relatively high installation cost and low FIT. This probably has to do with considerably more sunshine (2500ish in Sydney vs 1600 for the Netherlands).

Battery systems have fallen out of favor really rapidly because of the freefall pricing situation that solar modules are in. A sufficiently large battery, even the cheapest flooded cell lead acid batteries (~$0.10-0.12/Wh), will cost about the same as the solar installation, have quite a low efficiency (80% typical cycle efficiency at very low charge/discharge rates, worse with a smaller battery) and basically at this point will never pay back for itself. Even with these big differences between FIT and consumption cost. It seems fine at first glance, but a lot of people don't grasp the engineering behind battery systems. For instance, you can't efficiently charge lead acid batteries at high rates; they only achieve reasonable efficiency at C/30 to C/100. So you should install a battery that is 30 to 100 times as large as your actual energy need. At 20kWh/day (for a 3-3.5kWp system in AUS), that's a 600 kWh battery or about $60 000 - without chargers, without inverters. And even then you will still lose a couple tens of percents in efficiency losses. Lithium ion chemistries fare a lot better and can be scaled to C/2(ish), but they are about 5-10x as expensive per kWh and have slightly less charging cycles (about 2500-5000 at such conditions vs 10 000 for PbZn). Either way, lots more expensive than the actual solar installation, so your payback time on something like that will be tens of years or a century or something.

There are ways to optimize a battery system, undersize it and all that jazz but it'll never be cost effective unless energy prices are really high.

[Someone]

You'd need to interface it to several of your high consumption appliances and then it would decide based on your net export when its best to start using power. The 4 obvious appliances:

• Storage hot water tank, run with a high temperature cutoff higher than the standard thermostat (would require a tempering valve to keep the output temperature safe)

I have gas hot water

Which looks like a storage system, so it could have an element added to it to dump some power into. Though probably not worth the effort compared to waiting until it needs replacement and going for a solar unit at that time.

• Heat pumps, heat/cool your house a few degrees beyond your target when power is cheap, the insulation will keep it comfortable.

We don't have heat pumps in Oz, we have aircons, and I already mentioned I do this when required (not often)

Air conditioning systems in Australia are predominantly air source heat pumps. Depending on the specific gas tarrifs and COP of the heat pump it may or may not be cheaper to heat with it on mains compared to a gas heater, but your excess electricity going cheap would be cheaper by a good margin.

• Freezer, ideally with a fan forced fridge to use the stored energy as the food in the fridge won't tolerate temperature cycling like the frozen food will.

We don't have a dedicated freezer.

Many all in one fridge/freezer combinations are already using this technique of pumping the freezer air through to the fridge section to maintain its temperature. Reworking the control system with different setpoints for the freezer depending on the availability of excess solar power could reduce the running cost of a typical fridge/freezer by more than half which will more than pay off the cost of the conversion over the life of the fridge if you do it your self. This is the sort of feature which would cost almost nothing to integrate with the fridge when its designed but there is "no market" for, just like very energy efficient chest fridges.

Basically, there is nothing we can "automate" that would save anything.

There is but its a lot of work, changes in behaviour would probably be able to save more power.

[funkyant]

Yeah, I have to say Dave that I would expect you of all people to have some battery storage hooked up. It seems ridiculous that your electrons are worth so much less than the grids electrons.

[SNGLinks]

I've had solar panels fitted to my house here in the UK in October '13.  It's a small terraced house so the panels almost cover half the roof.
I'm fortunate that the roof faces due south.

As I'm 68 it was not viable to pay for a system so I went for the free option!
I lease the space above my roof to a company and in return they fit the panels for free. I get to use the electricity they generate but the company
get the feed-in tariff.

The smart meter shown sends them a reading so they can claim it.

I originally has an old style meter fitted (rotating disk) but it was not compatible with solar power as it went backwards when the sun shone
The electricity company changed it    

Total power generated to date: 3441kWh

https://www.flickr.com/photos/snglinks/sets/72157637134670794/

[Someone]

Yeah, I have to say Dave that I would expect you of all people to have some battery storage hooked up. It seems ridiculous that your electrons are worth so much less than the grids electrons.

Its complex in Australia as you generally cannot have batteries that are interconnected with the grid, they need to be a changeover system which adds some significant complexity.

[adream]

For your info:

You can cheaply log generation and usage for Mains AC on a diy scale using a combination of a "current cost" style energy meter, a Raspberry Pi and some open source software called "measureit"

I got my current cost meter fro about £10 second hand on ebay
Pi is about 25 quid
and the software is free
The system sips power (approx 3 watts)

The pi can host the data as a web page, AND upload data to PVOutput.com, so in Daves case he could fill in the missing data from his PVOutput tables

Links:
my old and tired pi hosting some sample data  http://fluffyasfuck.com:82/
and example of the current cost meter on ebay  eBay auction: #151370948522
And Measurit  http://lalelunet.github.io/measureit/

sorry about the urls above, I always get confused by forum code
and sorry about the rude word above, its my domain, what can I do :-)

[EEVblog]

A pool has running and maintenance costs and does not match everyones lifestyle ambitions. So it may be a feature but people value the benefits of something and not the feature itself.
Probably no-one would get rid of (or even switch off) a working solar system. Both a pool and a solar system are features, but a solar system would be a benefit to nearly everyone, but a pool not necessarily.

Exactly. In many cases a pool can actually be deal breaker, either way actually. Some people it's a must-have for the kids, others don't want it for fear of drowning kids and/or  maintenance or space etc.
The only possible reason I can think of to remove a solar system would be looks, some people just don't like them, esp if they are prominent on the front of the house

[KTP]

Yes, we have storage for our 1080 watts (four Mono-X panels) in our truck camper.   We use two Lifeline 12V 125 AH AGM connected in series (24V system).   Really too small a battery for the amount of solar, but over-paneling means we get some charging current even in cloudy conditions.

As far as battery efficiency, the Lifeline AGM can be bulk charged at insane rates...100 amps would not be too much for our small bank even though 45 amps is about the max we could get on 24V with only 1080 watts.  They require about 105% to 110% of the current drained from them to recharge them, the rest is lost in heat.   Lifetime at 50% DoD is around 1000+ cycles.   After bulk charging gets you to 85%, the remaining absorption charge takes 2 to 4 hours to get you to 95% to 100%.

It might not make sense to have storage for a permanent house, but a off grid truck camper parked in some remote area storage makes a hell of a lot of sense.

We may use the "waste not" feature of the Midnite solar MPPT controller to dump excess power into our 6 gal water heater when the batteries are topped off.

[jarrodhroberson]

Nice analysis, even if I could put panels on my house, which I can't because of multiple reasons, it would appears it would be a losing proposition for me.

We pay $0.062 kWh 7AM - Midnight and $0.0498 kWh from Midnight to 7AM because of a special rate I get from my electric cooperative because I have an Electric Vehicle they give me a discount on the entire house year round!

Just based on my usage and the winter rates that is about a 25% decrease in my bill, will be 30% or more for summer rates in the SouthEast US!

[PostaL]

Can one choose not to export the excess energy to those greedy bastards ?

[BurtyB]

I don't know how your inverter works but here in the UK our EVER Solar TL-4000GB doesn't export through the whole cycle so even when we're generating more than we're using we're still reliant on the grid for power at the start of the cycle which we're billed for .

With the solar isolated (yellow trace is the AC butchered through a small transformer and blue is a current clamp over the cable to the electric meter)


Solar exporting


The solar is connected to the fuse box and you can see it's still importing during the first part of the cycle and then starts to export for the rest of the cycle (other than the big peak at the end where we're not generating enough which I'd assume is caused by those pesky SMPS) I'm wondering if the initial "listening" phase might be related to the island protection?

[Seekonk]

If you want to get into solar but are put off by the price or size, think hot water. Many homes have electric water heaters with two elements.  Just 300W of panels is enough to make a serious dent in electric useage of this device. Look at this kit selling on ebay for $265. It explains the general idea better than I can.  Almost anyone can design a board better than this one, IGBT just wastes about 10W in heat and storage caps aren't sufficient to last many years  http://www.ebay.com/itm/Solar-Water-Heater-EZ-Kit-Save-No-Pipe-Changes-Hot-Water-System-PV-MPPT-/251735069810?pt=LH_DefaultDomain_0&hash=item3a9c945472   
 This is their technical link http://techluck.com/

No need to worry about net metering, expensive grid tie, or storage batteries (which average 12 cents a KWH, more than your electric). If you stay under 400W, 100% of potential solar power is actually used. A 36V panel string at power point is enough voltage to use standard heating elements. 2000W 120V elements available at any big box building supply work even better. A cheap micro with some junk box parts and you have a system.  Anyone can find a place for three panels around the house.
No need to sense current. with a fixed resistance PWM gives enough info to calculate power point.

This will be the future of solar just like adding extra insulation to the attic became common.  Several utilities investigated heat pump water heaters as a way to reduce peak loading in the morning and evening, search HOTSHOT documents. Just think of the energy reduction if everyone used this solar augmentation.   

[Oliverb]

Hi Dave,
nice video on the solar system.
I'm working here in Germany at a heat pump manufacturer with SMA on automizing heat pumps with the SMA Sunny Home Manager.
In your case a hot water heat pump would be a good idea. They use a 500W cold engine and have a 300 Liter storage tank. With one kWh, 8 cents in your case, they produce 4 kWh thermal energy.
So in your case ist is 2 cent/kWh for the thermal energy which should be much less than gas.
Also CO2 savings are huge.
Your SMA inverter can be equiped with a simple relais solution to start the heat pump when the PV system reaches a certain threshold.
If you are interested send me a PM.

Regards,
Oliver

[SeanB]

I just looked at my electric bill, and the price I pay is $0.10 per kWh. As the suppliers currently do not allow a feed in tarrif or even grid tie, you cannot do a solar system legally, unless you go like Martin Lorton did and go with batteries and partly off grid.

I just use a small 30w panel and a 12V 60Ah battery, to do lighting and other low power loads. Helps when load shedding is active and I estimate it has been worth it, even though I have had to buy a new 60Ah battery this year to replace the aging one in the system. I paid more for the battery than what the system originally cost as used.

[tcleavela]

If you want to get into solar but are put off by the price or size, think hot water. Many homes have electric water heaters with two elements.  Just 300W of panels is enough to make a serious dent in electric useage of this device.

Heating water consumes around 40% of my bill. I've considered a passive system but this is an intriguing alternative. Even if it cost 800 bucks it'd pay off in about a year.

[DanielS]

Yeah, I have to say Dave that I would expect you of all people to have some battery storage hooked up. It seems ridiculous that your electrons are worth so much less than the grids electrons.

Its complex in Australia as you generally cannot have batteries that are interconnected with the grid, they need to be a changeover system which adds some significant complexity.

I would not expect batteries to make any difference here: the inverter already needs the line voltage reference to lock phase with so it can adjust its output accordingly to export power and needs to shut down if power fails since it cannot drive the whole neighborhood including the local distribution transformer and whatever might lie beyond that on its own without tripping over-current or under-voltage protections. Regardless of what the exported power source is (PV, battery, generator or whatever else), export needs to stop when loss of mains is detected.

Adding batteries changes nothing to the inverter's operation aside from smoothing out PV output variations and enabling time shifting of PV energy use. You should only need a switch-over/disconnect if you want to be able to use the panels and batteries to operate off-grid during outages.

[German_EE]

A friend of mine has a solar power system that works rather well, the principle is as follows:

Assuming incoming solar power

1) Are the accumulators charged? This is important because the whole house runs off these accumulators via sine wave inverters.

2) If the accumulators are charged is there hot water? He has two massive insulated water tanks and this is the next destination for the power.

3) (Summer) Dump excess power into the jacuzzi or air conditioning (Winter) Dump excess power into the under floor heating which is done using resistive mats.

In 2014 his annual power bill was 122 Euro.

[rolycat]

A friend of mine has a solar power system that works rather well, the principle is as follows:

Assuming incoming solar power

1) Are the accumulators charged? This is important because the whole house runs off these accumulators via sine wave inverters.

2) If the accumulators are charged is there hot water? He has two massive insulated water tanks and this is the next destination for the power.

3) (Summer) Dump excess power into the jacuzzi or air conditioning (Winter) Dump excess power into the under floor heating which is done using resistive mats.

In 2014 his annual power bill was 122 Euro.

The system sounds exceedingly expensive - what was the capital cost and the likely repayment period?
How long do these accumulators last before requiring replacement?

[Seekonk]

Heating water consumes around 40% of my bill. I've considered a passive system but this is an intriguing alternative. Even if it cost 800 bucks it'd pay off in about a year.
[/quote]

It will take more than $800.  I have a add on heat pump that cuts electrical usage in half and that runs about $1,000. They all have a COP of about 2 if you look in the fine print. Most hybrid water heaters like GE cost $1,600 and in ten years it has to be replaced.  It's like buying yourself a job.  Supplementing with PV solar is not a bad payoff compared to HPWH cost and it will extend the life of the compressor.  A tempering valve is needed with a large PV system so you can run the tank up to 145 degrees.  Lot easier to run a wire in an existing house than tubing and it will never freeze.  No maintenance on pumps.

[nixfu]

It seems much more expensive now for solar installation.  I know a few years ago the Chinese were apparently flooding the market with panels at below cost, and the US has stopped that I think so costs maybe have gone up.

It looks like it would be $10-15k US for a comparable system in the USA, which is much more than the ~$5k AUS you said you originally spent.

I also wonder if there have been any improvements in panels since the few years that Dave installed them.

[linx310]

I work in the solar water industry.  Its not as sexy as PV but your money goes a lot further if you live in a climate with lots of sun.

The solar water systems we have installed here in Texas will cut your water heating bill big time if you uses an electric water heater.

[LabSpokane]

The home solar is fantastic. What would even be better are Solar Freaking Carports to charge your EV at work. For most  8-5 workers, it's an excellent match between resource and demand.

[PA0PBZ]

When you include 2 summers and only one winter in your calculations wouldn't that show a bit optimistic payback time?
Or more generally: shouldn't you base payback calculations over full year periods? Anyone want to do the math?

[Seekonk]

I get tired of all these people that talk about panels under a buck a watt.  Where are they and would you want to buy them?  Just saw an article about the Australian Govt. Investigating cheap Chinese panels that are failing after three years and that they paid a subsidy for.  With UL, shipping, mounting and wiring there are no cheap panels.

[wemme]

Thanks for posting Dave, the Payback schemes just went the same way in New Zealand.
People are installing timers on their hot water cylinders to delay them until the solar power is available but even this is pretty half arsed.

[LabSpokane]

I get tired of all these people that talk about panels under a buck a watt.  Where are they and would you want to buy them?

Right here:  http://www.eco-distributing.com/Solar-Panels_c_150.html

Many of them are polycrystalline and good quality.  It's not just the crappy thin film panels that are less than a dollar/watt now. Eco is a legit company, I have purchased a couple panels from them. 

Also, I think one might even get the higher end panels at sub $1/W if you call and purchase in pallet quantities.  That's not really an unrealistic plan if you go in with neighbors or do a joint community solar project. 

What you *can't* buy so far in the US is under a buck a watt *installed*  - even on a utility basis so far.  So, the new focus in solar is getting the "balance of plant", permitting, and installation costs under control. 

[tombi]

Hello,

I'm one of the lucky people Dave mentioned in that we installed a 1.5kW system under the 60c tarriff. The vendor even offered terms so it cost $120/month for two years to pay off and interestingly, mine generates around 5kWh per day on average which covered most of the monthly cost. So it pretty much paid itself off in 2 years.

At the same time I arranged for a similar system to be installed at the sailing club where my kids sail. I've had no problems with mine but the one at the club has had long periods of outage.

The problem is the club is on a peninsula and the voltage can vary from 230v to over 260. The Sharp inverter's maximum is 260 so after that it stops pushing power into the grid. Unfortunately this would happen at about 10 am when everybody has gone to work and when when the sun is in the sky. It took a lot of calls to the power company but they eventually adjusted the system to mostly sort this out.

Even if I had to go to net metering, solar would make sense for me as unfortunately this house has a pool. I also work from home so I am running computers in the day.

We installed a heat-pump for water heating which reduced the water heating consumption from around 10kWh/day to 2.5kWh/day. This doesn't change the bill much though because it is running on Off peak (CL2) which is half price anyway. Here in Australia we have two off peak systems (Controlled Load 1 and 2) where 1 goes off only at night and 2 goes off at various times of the day when the grid usage is low. The heat pump is on CL2.

Not sure why Dave is paying a CL2 tariff when he has gas for hot water... Only had two meters so definitely no CL2.

The pool runs low speed pumps to reduce consumption but it is still bad (200W for 12 hours a day).

Tom

[nowlan]

It looks like it would be $10-15k US for a comparable system in the USA, which is much more than the ~$5k AUS you said you originally spent.

I think most of the panels here are subsidized via Renewable Energy Certificates. Link

[mtdoc]

I get tired of all these people that talk about panels under a buck a watt.  Where are they and would you want to buy them? 

HERE and HERE

Solar panels are a commodity item now. All of the major manufacturers produce quality panels with similar warranties (20-25 yrs).

You can pay a premium for certain "top of the line" panels but you'll get very little benefit - maybe slightly better efficiency and workmanship  But with panels so cheap, it almost always makes sense to just buy a few more panels rather than pay for more expensive panels.

[darrenb]

We live a couple of km's from Dave in Castle Hill and installed our 2kw system in June 2010 when the government was offering the 60 cents per kWh gross feedback that Dave was talking about.

At the time it was easy to calculate that at 60 cents per kWh a system would pay for itself in a few years and there was a general rush to have a system installed.

Our 2kw system with inverter cost $2,500 installed with a 2kw inverter.  We had to pay an additional few hundred dollars to have the system wired into the meter box.  We didn't go for any upgrade options but the system has been reliable so far with no reduction in output.

I have all the figures since June 2010.  The system has made on average 7.4 kWh per day from installation until now.  Our electricity bill has gone from over $2,000 per year to about $100 per year.  In the warmer quarters we usually end up with a negative bill and the credit is carried through to the winter months which usually use up any credits that we have accumulated.

On our last bill we used 1205 kWh of general electricity at 18.93 cents per kWh and 732 kWh of off peak (hot water) electricity at 6.31 cents per kWh.  The solar panels made 848 kWh at 60 cents per kWh.  The final figure on the bill was that the electricity company owes us $141.80.

This was a crazy system by the goverment but it did kick start the solar industry here.  The system was guaranteed for seven years from when it commenced and will end at the end of 2016.  I'm not certain what we will do then (or before) but a timed heat pump driven hot water system which can use solar during the day looks like an obvious upgrade.

[mtdoc]

It seems much more expensive now for solar installation.  I know a few years ago the Chinese were apparently flooding the market with panels at below cost, and the US has stopped that I think so costs maybe have gone up.

It looks like it would be $10-15k US for a comparable system in the USA, which is much more than the ~$5k AUS you said you originally spent.

I also wonder if there have been any improvements in panels since the few years that Dave installed them.

True $5k for a 3 kW system is a good deal. I don't know how it works in Australia but in the US several companies have "lease" type installation agreements where they are able to claim  the 30% federal tax credit so the homeowner's installed cost is similarly low.

Panels in bulk are purchased at near $0.50 per watt . Depending on the size of the system, a strict grid tie system should come in at under $3 per watt.

And as far as I'm aware, no major improvements in commercially available PV panels in the last few years.

[cosmicray]

I get tired of all these people that talk about panels under a buck a watt.  Where are they and would you want to buy them? 

HERE and HERE

Solar panels are a commodity item now. All of the major manufacturers produce quality panels with similar warranties (20-25 yrs).

You can pay a premium for certain "top of the line" panels but you'll get very little benefit - maybe slightly better efficiency and workmanship  But with panels so cheap, it almost always makes sense to just buy a few more panels rather than pay for more expensive panels.

The LG MonoX that Dave mentioned are listed on that first link, then click 24V. They are roughly priced at $2/watt.

[poida_pie]

I have a self built system, 3kW peak, batteries, inverter, 240AC changeover switch.

aims:
to replace some power usage each day.
The amount of power available on any day is indeterminable and also could vary from 1 kWhr to 20kWhr
depending on season and weather.
IF insufficient power available from solar, use street power for balance required.

facts here in Melbourne:
$0.31/kWhr for electricity from any supplier.
approx 4.5 hours sunlight per day average over a year.

facts world-wide in modern Western economy households:
short high peak electricity loads on top of a steady, low power base load.
My house has a base load of 600-800W which is present 24 hours a day.
This means 0.6 x 24 = 14.4kWhr base load plus short period peak power values.
My daily average energy usage is 17-20kWhr/day over entire year.
This 600W can easily be supplied from a well sized, efficient and decent inverter.
So I can save 3/4 of my energy usage by simply providing this 600W for 24 hours a day.

So, I chose a 3kW peak solar panel array, to feed a 15kWhr battery bank via a 60 Amp peak
charge controller (Tristar 60Ampr MPPT)
Inverter is Victron 3000 W peak, 2,500W continuous inverter. Max efficiency is at about 1/3 peak power,
this allows some headroom for growth.
system is based on 48V DC nominal battery.

Now, typically I obtain about 10 kWhr from the solar array, and this gets put into the battery with about
95% (NO! more like 80% edited 12:14pm) efficiency. Then during the day and following evening, I pull this power out of the battery via the inverter
to power SOME but NOT ALL of the house power. I might use 9kWhr of inverter power, which I do NOT have to buy from power company.

I have run separate general power outlets into most rooms that are all connected to the single 240VAC output
of the inverter, via other equipment.
I have all TV, DVD, computers, 4 fridges (don't ask, 4 fridges..that's insane)
kitchen toaster, kettle and pool pump etc all connected to the one 20A trunk line, supplied
via an 16A RCD contact breaker which is then connected to a change-over relay then the inverter.

The change over relay is the key to the entire system.
This can sense when one input stops and change over to the secondary input, and connect this
to the output. This allows me to provide 240VAC power for any period of time from the inverter and when not available, the relay will change over to use the street power as a substitute until the inverter powers up again.
All transparent and no need for human intervention.

Cost to me so far:
$3,600    solar panels
$2,300    Victron Multiplus inverter 48V/3000W
$700    Tristar 60A MPPT charge controller
$xxx    contact breakers, big-ass high rupture current DC fuses, wiring, etc
$400    Latronics change-over relay ACTS40
300Ahr 48V battery bank came free of cost. (ex Telstra mobile phone tower batteries destined for recycling)

I have data to show I am averaging about 8kWhr self supplied energy per day.
This is 8 x $0.31 = $2.48 per day saving of electricity. Does not sound much.
365 x $2.48 = $905 /year.
break even on investment approx 7 years
And we get to tell the foreign investors of our privatised power companies
to stick their product up their fucking arses. (value of this = $priceless)

Note well:
Electricity costs will increase in the future in large increments because they can.
After the faux privatisation of state electricity here in AUS, the Elec suppliers can name their own prices now
All in the name of "Free enterprise/competition/captured markets/corruption/what-have-you"
So my system will get better as the price of elec. rises as it must.

I chose a nominal 100V DC solar array, coming into the charge controller to charge a 48V nominal battery bank.
This optimises the I2R (resistance) losses in the cable from panels to the charge controller (15 meters x 2)
and it then permits the highest efficiency inverter, being 48V DC.
Your installation may require different design factors for optimum performance.

go for it if you have the $$$. No need for a complete stand alone off grid system.
You can make 3/4 of total savings possible at 1/4 the cost.

A full on off-grid system needs 5X the batteries, 4x solar panels, 2X inverter and changes to house lifestyle.
All for the final 1/4 savings. Not worth it unless you must go off-grid.

[mtdoc]

I get tired of all these people that talk about panels under a buck a watt.  Where are they and would you want to buy them? 

HERE and HERE

Solar panels are a commodity item now. All of the major manufacturers produce quality panels with similar warranties (20-25 yrs).

You can pay a premium for certain "top of the line" panels but you'll get very little benefit - maybe slightly better efficiency and workmanship  But with panels so cheap, it almost always makes sense to just buy a few more panels rather than pay for more expensive panels.

The LG MonoX that Dave mentioned are listed on that first link, then click 24V. They are roughly priced at $2/watt.

Yep.  And if you bought them for that price you'd be paying over twice as much to get 16% efficiency instead of 15% efficiency. Not worth it. Like anything else, there's a lot of marketing hype with solar panels.

Unless you are really limited on space it almost never makes sense to pay a premium for higher efficiency panels. In the case of the LG Mono X versus another panel - say a Sanyo panel at $0.71 per watt (15% efficiency),  the same sized array would take up minimally more roof space.

Some panels put out slightly closer to STC specs on average but the differences are very, very small. Mono (versus Poly) supposedly output better in cloudy, diffuse light conditions but head to head testing has shown this to be a very small effect.  Just installing 5% more array (at less than half the cost) would give you more output.

That being said, I'm doubt Dave paid that much of a premium for his panels since his entire system came in at less than $2 per watt installed.

Also - paying a premium for a top quality inverter (like his SMA) is worthwhile IMO.

[EEVblog]

Yep.  And if you bought them for that price you'd be paying over twice as much to get 16% efficiency instead of 15% efficiency. Not worth it. Like anything else, there's a lot of marketing hype with solar panels.
Unless you are really limited on space it almost never makes sense to pay a premium for higher efficiency panels. In the case of the LG Mono X versus another panel - say a Sanyo panel at $0.71 per watt (15% efficiency),  the same sized array would take up minimally more roof space.

It's not about efficiency, it's about build quality and local warranty support.
It's a much safer bet that LG will produce better quality panels than WunHungLo on ebay, and they'll be around in 20 years time to use that warranty if needed.
That's why I paid more.

[coppice]

Yep.  And if you bought them for that price you'd be paying over twice as much to get 16% efficiency instead of 15% efficiency. Not worth it. Like anything else, there's a lot of marketing hype with solar panels.
Unless you are really limited on space it almost never makes sense to pay a premium for higher efficiency panels. In the case of the LG Mono X versus another panel - say a Sanyo panel at $0.71 per watt (15% efficiency),  the same sized array would take up minimally more roof space.

It's not about efficiency, it's about build quality and local warranty support.
It's a much safer bet that LG will produce better quality panels than WunHungLo on ebay, and they'll be around in 20 years time to use that warranty if needed.
That's why I paid more.

So, you think Panasonic, who now own Sanyo, are more likely to go out of business than LG? Could be, in these rapidly changing times. More importantly, perhaps, is who is actually providing these warranties. People often think they have a warranty from a huge stable corporation that can be relied on, only to find out their warranty agreement is with a subsidiary that gets closed down. This happens a lot with home construction.

[zapta]

I've never had any money to invest, so maybe I'm way off base here.....
But I get the impression that it would make more financial sense to invest that $5k in the stock market.
Eight years of compounding savings versus just getting your money back (Does this equipment retain its value on the second-hand market or would people be silly to buy used?) then hoping you can turn a profit near the end or after the warranty has expired.

Dunno.  Just thinking out loud.

You are thinking well.  It's called opportunity cost, an important part of every serious investment analysis. 'the value of my house went up' doesn't necessarily mean that it was an efficient investment.

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

[mtdoc]

Yep.  And if you bought them for that price you'd be paying over twice as much to get 16% efficiency instead of 15% efficiency. Not worth it. Like anything else, there's a lot of marketing hype with solar panels.
Unless you are really limited on space it almost never makes sense to pay a premium for higher efficiency panels. In the case of the LG Mono X versus another panel - say a Sanyo panel at $0.71 per watt (15% efficiency),  the same sized array would take up minimally more roof space.

It's not about efficiency, it's about build quality and local warranty support.
It's a much safer bet that LG will produce better quality panels than WunHungLo on ebay, and they'll be around in 20 years time to use that warranty if needed.
That's why I paid more.

Dave-  I'm not talking about "WunHunLo" panels from eBay. Look at the link I posted - HERE.  I'm talking about top brand, top quality panels like Sharp, Canadian Solar, etc that are priced less than 1/2 the price of the LG panels at that particular  vendor - who BTW is one of the largest in the US..

I have no idea how much of a premium you may have paid. And you're right that local warranty support could be important (though PV panel failures are very rare).  Paying a small premium may be worthwhile in some cases. But in my experience and from talking to many others who have installed PV systems - the workmanship of all the top brands is similar.

Again - any extra you paid might have been worth it - I don't know the specifics of what your choices were.  In any case at $5K for a 3kW system with a SMA inverter - you did well, regardless of the panels.

My comments were only referring to the >2:1 price differential from that particular vendor and the general point that paying a lot extra for one top brand over another is generally not worth it.  Just my $0.02

[mtdoc]

Another point to consider on panel price/watt. The recent trend is to make bigger and bigger panels. The main advantage is it can save on mounting hardware, wiring, etc. Since panel prices have bottomed out - saving on installation BOM hardware costs have driven companies to market larger panels.

The downside is they are more difficult and unwieldy to install!

[free_electron]

I had to go out and clean snow off the panels several times.

Snow? What's that? I don't understand...

i heard it is state of water and falls from the sky. i vaguely remember water  droplets falling from the sky, but those were in liquid form.

I also heard stories about some people that go in search of it on mountains tops and strap wooden slats , kinda like 2 by 4's , to their feet to use it to glide very fast back down the mountain. I guess it must be to make up for the time wasted climbing the damn things, and searching for this fabled substance, in the first place.

[bills]

I had a 3 kw system installed 8 years ago,it was costly $20k with rebates and tax credit it cost $12k ( I refused to pay the last $3k until they made it produce 3k it will make 2.5k on a good day)
My bill was $300.00 per mo. in summer $80-$100 for the rest of the year,now my power bill is $300.00 to $400.00 per year. still  only makes 2- 2.5 kw. so for $9k I am happy.
BTW they never tried to collect the $3k.
All components were mfg. by sunpower and have a 20 year  warranty.

[rs20]

I had a 3 kw system installed 8 years ago,it was costly $20k with rebates and tax credit it cost $12k ( I refused to pay the last $3k until they made it produce 3k it will make 2.5k on a good day)
My bill was $300.00 per mo. in summer $80-$100 for the rest of the year,now my power bill is $300.00 to $400.00 per year. still  only makes 2- 2.5 kw. so for $9k I am happy.
BTW they never tried to collect the $3k.
All components were mfg. by sunpower and have a 20 year  warranty.

Did they actually try to deceive you by saying that a 3kW system produces 3kW? Do you have a sun-tracking installation? Because everyone knows that the nominal watt figure on these panels are under extremely idealised, artificial circumstances.

[bills]

no they said i would get 3kw i did not!
They told me that they fired the salesman ( I don't care I was  expecting 3kw) I told them I needed at least 2 more panels to get the required out put and offered to pay extra for them, they dropped the ball and it cost them.

[bills]

BTW I have 2 panels 250w on order to fix it myself. my existing panels are 235w hope these will work.

[C222]

Hey everyone.
I work at a solar power provider and took some halfway decent images of our solar inverter testing setup.
Where would be the best place to share the album? New topic? Which subforum?

[G7PSK]

When we put the house up for sale one of the questions asked by the solicitor was is there a solar panel on the roof. When I asked why this question was there I was told that Mortgage company's do not like them especially if they were installed by one of those company's that install them at no cost in order to get the feed back tariff.

[SNGLinks]

When we put the house up for sale one of the questions asked by the solicitor was is there a solar panel on the roof. When I asked why this question was there I was told that Mortgage company's do not like them especially if they were installed by one of those company's that install them at no cost in order to get the feed back tariff.

The company that fitted my free solar panels state on their web page:

Over 3,000 homes have already been sold with our free solar panels installed on the roof and we have never had any problems arise with new homeowners. The Energy Saving Trust estimates that homes with solar sell around 30% faster than homes without.

[G7PSK]

When we put the house up for sale one of the questions asked by the solicitor was is there a solar panel on the roof. When I asked why this question was there I was told that Mortgage company's do not like them especially if they were installed by one of those company's that install them at no cost in order to get the feed back tariff.

The company that fitted my free solar panels state on their web page:

Over 3,000 homes have already been sold with our free solar panels installed on the roof and we have never had any problems arise with new homeowners. The Energy Saving Trust estimates that homes with solar sell around 30% faster than homes without.

I think the problem arises due to what in effect is a lien on the property it makes a bit more work for the legal team but yes it should not make ant difference at all, my experience with lawyers though is that they are a lazy lot and wont do anything without being chased all the way, if there was any problems the installation company would hardly be likely to advertise the fact.

[Red Squirrel]

Great video, always cool to see these kinds of setups.

I keep looking into going solar, but I really don't think it would be worth it where I live.  I'm in Northern Ontario.  On the other hand for the few months of summer that we DO get, the sun is up at like 4am and goes down around 10pm, so that's a long time if there are no clouds.  So I suppose it could at least offset the cost of AC perhaps?  Or is that a long shot?

I also have to account for the power usage of whatever system I'd setup to get rid of snow.  Some kind of brush system would probably be more efficient than heat.  Or perhaps a piston system that tilts the panels over and lets the snow drop.  The same system could also be used for solar tracking at least on one axis.

Here is some solar insolation data for my area, are those numbers good or bad?

http://pv.nrcan.gc.ca/index.php?n=3143&m=u&lang=e

[mux]

I get tired of all these people that talk about panels under a buck a watt.  Where are they and would you want to buy them?  Just saw an article about the Australian Govt. Investigating cheap Chinese panels that are failing after three years and that they paid a subsidy for.  With UL, shipping, mounting and wiring there are no cheap panels.

There are zero solar panels I can buy for over $1/Wp (Netherlands). The cheapest ones are about €0.45/Wp, the most expensive ones (e.g. Yingly Panda YL275-C) are about €0.80/Wp. At current exchange rates $1~€1. Even exotic panels like the Sanyo HIT 240s (which have very high efficiency, to use on super-tight roofs) are below €1/Wp.

Entire installations, including all costs, start at just below €1/Wp. Prices are so low that people often choose for higher quality/all black (=purely cosmetic)/fake panels (to fill up visually empty space)/additional crap. With all that, average installation prices have dropped from €1.75/Wp to €1.55/Wp in the past 12 months in the Netherlands.

This is all without any subsidies, including import taxes (that are useless because prices have dropped so much since, that panels are cheaper than they have ever been). You can get about €0.20/Wp effective rebate on your entire installation if you ask for VAT back (which is a subsidy for solar right now).

The US has always been significantly more expensive with solar, and not for any obvious reason afaik. You use the exact same panels, same inverters, not much is technically different. Subsidies and incentives have been astronomical in the US over the last 10 years, waaaaay more than we've ever had in Europe. First Solar and Solyndra being two of the main examples, getting a combined $1B in tax breaks and subsidies, not to speak of the big govt. expenditures on california's (world-leading) solar farms. The subsidies in Germany pale in comparison to that. So you can't blame the government.

[nctnico]

Yep.  And if you bought them for that price you'd be paying over twice as much to get 16% efficiency instead of 15% efficiency. Not worth it. Like anything else, there's a lot of marketing hype with solar panels.
Unless you are really limited on space it almost never makes sense to pay a premium for higher efficiency panels. In the case of the LG Mono X versus another panel - say a Sanyo panel at $0.71 per watt (15% efficiency),  the same sized array would take up minimally more roof space.

It's not about efficiency, it's about build quality and local warranty support.
It's a much safer bet that LG will produce better quality panels than WunHungLo on ebay, and they'll be around in 20 years time to use that warranty if needed.
That's why I paid more.

I'm not sure whether that is good reasoning. A cheaper panel may have a shorter life but overall the total cost may be lower. By the time the cheaper panel needs to be replaced better panels are probably available so all in all you may do much better getting a cheaper panel. IMHO the time to recoup the investment should be around 5 years (preferably less). Besides that you pay for the warranty as well.

BTW: nice to get back on the solar panels and show some numbers. Do realise that -unlike people in the US and Europe- you are in area with a lot of sunshine. I don't like the way they fed the cables through the roof tile. When I fitted my airco I used a special feed-through tile which is much more wheater proof.

[mtdoc]

I'm not sure whether that is good reasoning. A cheaper panel may have a shorter life but overall the total cost may be lower. By the time the cheaper panel needs to be replaced better panels are probably available so all in all you may do much better getting a cheaper panel. IMHO the time to recoup the investment should be around 5 years (preferably less). Besides that you pay for the warranty as well.

Good points. As far as warranties go - they do not vary much among manufacturers. The standard is 80% of STC rated output at 25 yrs.

Do realise that -unlike people in the US and Europe- you are in area with a lot of sunshine.

Not exactly. It depends on where in US or Europe. Much of the US southwest has equal or greater solar insolation than Sydney and I think that's true for parts of Europe (Spain?).

But -because of the drop in PV prices - this is less important that it once was. More PV can compensate for less sunshine at a modest additional cost.

[nctnico]

That may be but AFAIK large parts of Australia are closer to the equator than Spain (which stretches furthest to the south compared to other European countries) or the southern parts of the US.

[mtdoc]

True, but it's not just about latitude. It's also about average cloud cover.

[LabSpokane]

True, but it's not just about latitude. It's also about average cloud cover.

Yup. Which is why the SE and SW regions of the USA have very different insolation values at the same latitude.

[mtdoc]

And because of the drop in PV prices, even I, living in the top left of that map can produce more electricity for less money spent on PV than someone could 5 years ago living in the bottom left of that map. (and I don't have to worry about a water shortage  )

[C222]

and I don't have to worry about a water shortage

Or cleaning your panels!   

It's also amazing how sensitive some of the newer panels can be. I've heard stories at the office about my department pulling their hair out because they were getting power generation measurements from a house well after sunset.
Turned out, the house was across the street from a baseball field with its powerful lights on during gametime. That was enough to wake up the solar inverter and produce power.

[mtdoc]

It's also amazing how sensitive some of the newer panels can be. I've heard stories at the office about my department pulling their hair out because they were getting power generation measurements from a house well after sunset.
Turned out, the house was across the street from a baseball field with its powerful lights on during gametime. That was enough to wake up the solar inverter and produce power.

Yep, I've also seen measurable output from a full moon!

[reagle]

I get tired of all these people that talk about panels under a buck a watt.  Where are they and would you want to buy them?  Just saw an article about the Australian Govt. Investigating cheap Chinese panels that are failing after three years and that they paid a subsidy for.  With UL, shipping, mounting and wiring there are no cheap panels.

My Sunpower ACPVs ended up around $1.4/W installed after NYSERDA grant and Fed/state taxes. Almost there..

[SL4P]

How about use a Raspberry Pi as a controller to try to make the best use of the energy during the day?

Huh?
How?

Dave - You're normally pretty fast with these kind of things...
Everything can be made better with an Arduino or RasPi - along with duct tape and hot-snot.

[WBB]

How about use a Raspberry Pi as a controller to try to make the best use of the energy during the day?

Huh?
How?

Dave - You're normally pretty fast with these kind of things...
Everything can be made better with an Arduino or RasPi - along with duct tape and hot-snot.

And bailing wire, don't forget the bailing wire. The earth would literally crumble to pieces without the stuff.

[DrGeoff]

Thanks for this Dave. I was hoping to see your solar stats before deciding on the size and type of installation to pursue here (about 10km from you). Have been looking at using micro-inverters, which are essentially an inverter per panel, to reduce partial shading effects.

[HackedFridgeMagnet]

I might have missed this as I watched the video a few days ago.
Did the costs include any rebates or subsidies, such as RECs?
In Australia often the installers did get the client to sign these over as part of the discount price.

Though it is probably cheaper now to install solar than it was before even with the RECs.

[Poe]

I've never had any money to invest, so maybe I'm way off base here.....
But I get the impression that it would make more financial sense to invest that $5k in the stock market.
Eight years of compounding savings versus just getting your money back (Does this equipment retain its value on the second-hand market or would people be silly to buy used?) then hoping you can turn a profit near the end or after the warranty has expired.

Dunno.  Just thinking out loud.

You are thinking well.  It's called opportunity cost, an important part of every serious investment analysis. 'the value of my house went up' doesn't necessarily mean that it was an efficient investment.

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

So I did a bit of research.  Please point out any mistakes because this interests me..

As Dave mentions, due to Australia's disparity in generated/imported energy costs, his ROI could have significantly shorter if he simply installed fewer panels.  Two years is possible!  The excess panels (over what he consumes) are probably a really really poor investment. 

Although I think this highlights the fact that, to be fair, his investment was only a good one due to Australia's high cost of electricity, low installation costs, and high insolation levels. 

My payback period for a similar system would be >20 years. 

Installed cost ~$10k.  $13k if I want a ten year inverter warranty.  (Sunnyboy 3000TL factory warranty is five?).  In my area specifically, 2MWh appears to be a very generous annual generation estimate for a 3KW array.   At $0.118 per KWh (same price generated/imported), that's ~$275 worth of electric savings and a payback period of thirty years (assuming I go with the cheapest inverter).

The price drops substantially if I install the system myself (my time has no value), but the payback period would probably still be outside of the warranty period.

Due to the equal pay/charge structure, scaling up/down wouldn't affect the ROI either.

I'm better off investing that money (pre-tax) in a very low risk index and seeing >$7k in my bank around the same point Dave's system has paid for itself (net zero).  After twenty years, Dave's system would have generated <$9k while my investment would sit North of $13k.  All of that assumes no maintenance costs as well.

My scenario is not an outlier either.  Most countries have a lower cost of electricity than Australia.  Reasons for those high(er) costs are not interminable either. Some of those countries/states heavily tax non-green energy producers and funnel those funds to prop green projects.  Directly or through carbon credits, etc.  Others simply have an antiquated energy generating/transporting systems.  Australia's high prices are attributed to their temporary coal dependency (decreasing in favor of solar).

The chance of those things changing is more likely than the global market crashing IHMO.

Not to mention Australia's notably greater solar insulation than most of the developed world.

So I think solar is great in some geographical areas.  Although it appears to be a bad investment in most areas.... or only a good investment due to temporary government assistance. 

As resources become scarce it will surely become more a more sound investment in more areas.

[nixfu]

>Not to mention Australia's notably greater solar insulation than most of the developed world.


Yes, As a yank, I would be interested to learn how Dave gets away with needing so little air conditioning due to what he said about solar insulation.  We have no such technology in the US, it seems to take much air conditioning in our homes to keep the comfortable anytime you get close to 80F.

[SeanB]

First off Dave probably is comfortable in a warm room, so just keeping it at around 25-28C will not be a worry for him.

Second, he has insulated his house very well, having a thick layer of insulation in the walls and the roof space as well, to reduce heat ingress into the house. Double glazed windows along with a heat reflecting film on all windows as well helps. he did install a vent system into the attic space as well to reduce the heat build up in there as well.

This, along with some strategically located fans and light clothing ( no need for the Australian safety shoes insides), and generally being acclimated to a warm climate, along with low local humidity works to keep him comfortable.

[mtdoc]

There's a big difference between risk free ROI and market risk (despite what central bankers would have you believe).

Anyone who looks at a residential solar PV installation only in terms of a financial instrument will always be able to convince themselves that they can "make more money" by investing their capital elsewhere. They may or may not be correct - but if they don't understand the risks they are not necessarily making a sound financial decision.

I think for most people with solar PV there is a non-financial benefit they enjoy from producing their own electricity and watching their meter turn backwards.   This is not unlike someone who takes joy in building their own electronic gadget or repairing one instead of buying one for less money. Or the person who takes joy in their sports car when a used economy car would get them from A to B just as proficiently.

Installed cost ~$10k.  $13k if I want a ten year inverter warranty.  (Sunnyboy 3000TL factory warranty is five?).  In my area specifically, 2MWh appears to be a very generous annual generation estimate for a 3KW array. 

If you're paying $10 - 13k for a 3kW grid strict grid tied PV installation then you are overpaying.

[nctnico]

>Not to mention Australia's notably greater solar insulation than most of the developed world.


Yes, As a yank, I would be interested to learn how Dave gets away with needing so little air conditioning due to what he said about solar insulation.  We have no such technology in the US, it seems to take much air conditioning in our homes to keep the comfortable anytime you get close to 80F.

I've put a fairly large tree in my front yard to keep the sun out. It works quite well but it does need some maintenance.
I have an airco in the attic to keep my office cool. It would be interesting to determine what effect it would have if I installed solar panels on the roof. It should reduce the need for the airconditioning and simultaneously cut some of the cost (I need to keep the airco running long after the sun went down due to the heat accumulated in the roof tiles).

[Seekonk]

Trees can be an issue.  None of my1.5KW of solar panels are actually on my property. I've kept them low profile and hard to see.

[nowlan]

I do agree, you may be better off investing a lump sum of cash.
However, you havent factored the cost of electricity rising over 10-20 years in your analysis.

You want to size your system to your own demand. My parents are pensioners, who are home all day and can make use of electricity generated, but where will they be in 20 years? More likely the house will be knocked down for apartments sooner.

Golden rule is to minimize before relying on solar. Gas, solar hot water, insulation, energy efficient appliances, cfl/led lights.

[EEVblog]

As Dave mentions, due to Australia's disparity in generated/imported energy costs, his ROI could have significantly shorter if he simply installed fewer panels.  Two years is possible!  The excess panels (over what he consumes) are probably a really really poor investment. 

The thing is, I never really did it as an investment, I just wanted solar panels because I thought it would be cool. Just like for the last 15 years I've been paying an extra tariff to buy green power. There was absolutely no financial incentive to do that, it cost me extra money. I did it because I liked the feeling of supporting renewable energy infrastructure in this country.
This is why I've never done an ROI on the system until this video, because I know that's what most people want to know.

[EEVblog]

Yes, As a yank, I would be interested to learn how Dave gets away with needing so little air conditioning due to what he said about solar insulation.

SeanB nailed it.
We have good insulation in roof and walls, we have a vented roof space to prevent heat build up, blinds, concrete slab for large thermal mass, the house is aligned well etc.
It's only on the more extreme days during either winter or summer that we'll turn the aircon on for an hour or two.
Often I think "gee, we haven't switched it on for 3 months, I hope it still works!" and will in fact give it bit of a run now and then just to exercise it.
Used it much more since Sagan came along of course, SWMBO insists he must have a nice constant temperature  , so his room has his own aircon, But in that case it's incredibly efficient within a single small room.

[EEVblog]

First off Dave probably is comfortable in a warm room, so just keeping it at around 25-28C will not be a worry for him.

25C is starting to get uncomfortable, not so much at home, but in the lab yes. The lab will get to 25-26C without the aircon, so I often need to turn it on to cool it down a bit. I never have to heat the lab up BTW.

[SeanB]

My aircon at home has used 77.2kWh since it was installed. It has been in for over 5 years, and I do not use it much, almost half of that will be using it as a very quiet fan. Setpoint is 26C, as otherwise it is not comfortable for me.

At work the Frankensung in my office has died, rusted all the way through. No budget to replace it, bit I am comfortable at 27-28C with only a 120mm fan blowing air on me. Will brick up the hole soon when time allows, then will wait for another outdoor unit to die and be replaced so I get parts to make a Frankensplit. Otherwise i will look for a cheap $300 off brand split and get that.

[mtdoc]

Good solar insolation does not have to mean hot climate. I imagine that Sydney is similar to coastal Southern California where I grew up. Lots of sunshine and rarely hot. Most homes do not have air conditioners.

[Fungus]

I am comfortable at 27-28C with only a 120mm fan blowing air on me.

It's all about humidity. 27-28C in a humid area is unbearable.

Where I live it can go over 40C in the summer when the wind blows from the West (inland), but it's a dry air. You drink a lot more but you don't get all sweaty.

Those days are much more bearable than when it's 'only' 30C and the wind is blowing from the East (sea) - which it normally does 

[SeanB]

I lived for a few years in a small town, where you could predict the weather very accurately as follows. Daytime sunny, temperature reaching around 42C, night, low of 12C. 365 days a year of this. In winter we would be walking around with cold weather clothes as it was under 20C till 9AM, while the upcountry visitors were dropping from heatstroke. I put up a fan on the ceiling in my room, and turned it on. Only turned it off when I was moving out, and was not going to leave it behind.

[rw]

Hi Dave, love your blog. Solar power output can vary from factors other than the total light hitting the panels at a given time. As the solar panels heat up the power output goes down for the same solar input. The effect can be quite dramatic. I live in southern California, USA and my 5.2kw system has a maximum power output in both spring and fall NOT summer when the days are longer and the the sun is more directly aligned with the panels (read overhead). Also dirt on the panels can have a dramatic effect on output. Extremely dirty panels can derate by roughly 40%. Even seemingly, mildly dirty panels can lose the better part of 20% output. I have measured this effect when cleaning them in the cooler months. In the middle of summer, cleaning the panels with water also cools them so an even greater improvement can be had.

Thanks again for the enjoyable blog.

As a side note, I installed my system about 4 years ago and got similarly high end system and even after federal and state rebates on the system, it still cost me close to $20k. Australia is usually much more expensive for everything, but solar seems to be an odd exception. Input?

[TSL]

Good solar insolation does not have to mean hot climate. I imagine that Sydney is similar to coastal Southern California where I grew up. Lots of sunshine and rarely hot. Most homes do not have air conditioners.

Depends on what you call not hot - summer typically is 28-33 C and it can and does reach up to weeks of 40 - 42C and we get occasional peaks like the 49.1C we had in our backyards in the 2013/14 summers. I'd call that hot. The summer we just had averages around 30 +-3degC most of the time.

We have roof insulation and, before we added our panels, we had the roof painted with a IR reflective paint that reduced internal temps by 10deg.

Given we have lots of trees and thus moving shade patterns, we installed 4kW of Tindo AC panels, i.e. a micro-inverter on each panel. That way if a panel is shaded it doesn't effect the output of all the others.

regards

Tim

[mux]

Installed cost ~$10k.  $13k if I want a ten year inverter warranty.  (Sunnyboy 3000TL factory warranty is five?).  In my area specifically, 2MWh appears to be a very generous annual generation estimate for a 3KW array. 

If you're paying $10 - 13k for a 3kW grid strict grid tied PV installation then you are overpaying.

By like a factor of 4... no wonder the payback period is so incredibly long! That's 2007 prices!

[Slowmo]

Maybe it is worth thinking about burning the excess energy mining bitcoins? While I am not into this thing myself, it's just an idea...

[DimitriP]

Back to solar systems for a moment, , I'm having trouble with the $5000AU cost.
Either solar costs a lot less in AU or someone is lining their pockets in the US.

I'd like to hear from anyone in the US that paid for their own solar system.
Not as a part of any of the usual "knock-on-your-door" "won't cost you anything" deals.
By searcing around it looks like an inverter is somewhere between $2500-$2900 and  250W panels go for about $260 a piece.

12 Panels @ 260 = $3120
inverter @ 2600  = $2600
and we are already at $5720 US
Add installation  by the humans on the roof
Add cost of additional items like wires, conduit etc etc.
Add cost of permits, inspection
and the instalation cost starts going "cactus" as Dave would say !!!

[EEVblog]

Back to solar systems for a moment, , I'm having trouble with the $5000AU cost.

In Oz you can get a 5kW system installed for AU$4000 (USD$3k)
http://www.truevaluesolar.com.au/specials/

[DrGeoff]

Also in AU, about to get a 3kW system installed. 12 x tier-1 QCell panels and Enphase micro inverter under each panel.
All installed for 5K. Hoping to add batteries as well in a few years.

[EEVblog]

Hoping to add batteries as well in a few years.

In Oz battery solutions suck at present 

[DrGeoff]

Hoping to add batteries as well in a few years.

In Oz battery solutions suck at present 

Sure do. Installers recommend waiting for a few years to see what is left after the dust settles.

[EEVblog]

Sure do. Installers recommend waiting for a few years to see what is left after the dust settles.

Yep.
Unless you are on a remote property or something, I'd wait a few years too.
Every solution seems custom and bodged, Tesla will be the winners in this.
I contacted an Oz company that sells a nice looking German solution that seems similar to the Tesla powerwall, but didn't hear back from them. Meh.

[DrGeoff]

Sure do. Installers recommend waiting for a few years to see what is left after the dust settles.

Yep.
Unless you are on a remote property or something, I'd wait a few years too.
Every solution seems custom and bodged, Tesla will be the winners in this.
I contacted an Oz company that sells a nice looking German solution that seems similar to the Tesla powerwall, but didn't hear back from them. Meh.

And bodged lithium high-power battery packs can be quite dangerous. I can imagine that ther may be some regulations regarding their manufacture and installation eventually. It might be better to wait until there are standards and regulations.

[nowlan]

I think you guys have missed mentioning the STC (solar trading credits) which subsidize the prices here in Australia.

[mtdoc]

By searcing around it looks like an invertes is somewhere between $2500-$2900 and  $250W panels go for about $260 a piece.

Your PV pricing is way off. Panels can easily be had for half that . Even less for large installers who buy in bulk.

[HackedFridgeMagnet]

Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

[EEVblog]

Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

Oooooo 

[DrGeoff]

Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

Now that is tasty.

One issue I see with being completely "off grid" is that, without duplication of the system, a failure could see you powerless for quite a length of time as spares, repairs and replacements have to be sourced and installed. This could be a problem depending on what went wrong and how long it takes to fix.

[mtdoc]

Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

Now that is tasty.

One issue I see with being completely "off grid" is that, without duplication of the system, a failure could see you powerless for quite a length of time as spares, repairs and replacements have to be sourced and installed. This could be a problem depending on what went wrong and how long it takes to fix.

I believe these new battery systems(like the Sanyo and Tesla) are not really directed at off grid systems.  They are meant to be added on to traditional strict grid tie systems via "AC Coupling" topologies.

[DrGeoff]

Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

Now that is tasty.

One issue I see with being completely "off grid" is that, without duplication of the system, a failure could see you powerless for quite a length of time as spares, repairs and replacements have to be sourced and installed. This could be a problem depending on what went wrong and how long it takes to fix.

I believe these new battery systems(like the Sanyo and Tesla) are not really directed at off grid systems.  They are meant to be added on to traditional strict grid tie systems via "AC Coupling" topologies.

Sounds a bit like decoupling capacitors.
Allowing you to recharge during off peak (when power is cheap) and use it during peak times, ie local small reservoir for peak demad periods.

[LabSpokane]

Sure do. Installers recommend waiting for a few years to see what is left after the dust settles.

Yep.
Unless you are on a remote property or something, I'd wait a few years too.
Every solution seems custom and bodged, Tesla will be the winners in this.
I contacted an Oz company that sells a nice looking German solution that seems similar to the Tesla powerwall, but didn't hear back from them. Meh.

In the near term, Tesla could be making more money of their Powerwall than cars. The killer app is in peak shaving for business and office buildings.  The U.S. Northeast is a hot market for that right now.

[EEVblog]

Looks like there are a few system available actually, not sure how I missed them before.
The Samsung one, a Bosh one, and Sunnyboy!
http://rfisolar.com.au/browse-products/energy-storage.html

[DimitriP]

Back to solar systems for a moment, , I'm having trouble with the $5000AU cost.

In Oz you can get a 5kW system installed for AU$4000 (USD$3k)
http://www.truevaluesolar.com.au/specials/

Not that I didn't believe you, but thanks for the link. Wow!

[DimitriP]

By searcing around it looks like an invertes is somewhere between $2500-$2900 and  $250W panels go for about $260 a piece.

Your PV pricing is way off. Panels can easily be had for half that . Even less for large installers who buy in bulk.

Thaks for the link.
It looks like for the same capacity system the prices in AU are about half as much.
For $3000 US in AU you get a 5KW system up and running.
For $3700 US in the US you get a 3KW system parts that still need to be permitted, installed and inspected. Yeah...there is a small discrepancy there ....

I should probably get on the phone with local installers and quit bothering you guys.

It has been an eye opening experience regardfing pricing though. Thanks Dave!!!

[coppice]

I have a question about mounting solar panels.

I have been looking at some mounting frames for solar panels, and they don't look all that robust to me, especially for an area subject to typhoon/hurricane grade storms. In a severe storm these things are going to be like sails, trying to rip themselves away from their mountings. The mounting frames themselves don't look that tough; the way the panel clamps to them doesn't look that tough; and the way the frame fixes down doesn't look that tough. Are most of these mounting systems proving adequate in practice, or should I be really cautious about this area?

[mtdoc]

I have a question about mounting solar panels.

I have been looking at some mounting frames for solar panels, and they don't look all that robust to me, especially for an area subject to typhoon/hurricane grade storms. In a severe storm these things are going to be like sails, trying to rip themselves away from their mountings. The mounting frames themselves don't look that tough; the way the panel clamps to them doesn't look that tough; and the way the frame fixes down doesn't look that tough. Are most of these mounting systems proving adequate in practice, or should I be really cautious about this area?

Commercial mounting systems (and PV panels) will have specific engineering specifications regarding maximum wind forces, etc which will depend on panel size (surface area) and mounting type (roof versus ground mount).

Geographic locations will have specific data regarding expected maximum wind speeds, etc so that as long as the mounting systems engineering meets the needs for the geographic locale then all is generally fine. Of course with an extraordinary hurricaine or a tornado all bets are off.

Depending on the location - local codes or AHJ may require an engineers stamp certifying structural integrity,etc.

[apis]

Solar is really great, especially if you live closer to the equator. Unfortunately I haven't been able to justify a system here in Scandinavia from an economic perspective at the moment, we don't have that many sun hours either sadly and highest energy demand is during winter when there is even less sun. For a new house, if you go completely off grid, it might make more sense because you pay a lot to install the electric services so that could balance out some of the solar panel installation cost. I live in southern Sweden, that's about 55 degrees north, Sydney is 35 degrees south, that's similar to North Africa, perfect for solar! At least we don't have those huge spiders here.

[mux]

The nice thing about Sweden in particular is that you've got a couple of big low-budget solar manufacturers like REC and Aurora that drive the prices down. Sweden has the lowest installation cost after Germany and Denmark.

I get sub-3 year payback times with my system in the Netherlands with only about 10% more sunlight than southern Sweden:

http://www.sapa-solar.com/images/annual-global-irradiation.gif

[apis]

The nice thing about Sweden in particular is that you've got a couple of big low-budget solar manufacturers like REC and Aurora that drive the prices down. Sweden has the lowest installation cost after Germany and Denmark.

I get sub-3 year payback times with my system in the Netherlands with only about 10% more sunlight than southern Sweden:

http://www.sapa-solar.com/images/annual-global-irradiation.gif

Is <3yr payback a measured result from an actual installation or a theoretical estimate? This far north the angle of the sun is pretty low during winter as well which I expect would be detrimental, there are many factors so it's hard to be sure what to expect (at least there is hardly any snow these days). But maybe I should look into it again.

[Delta]

3 year payback? Wow!
What is the cost of a kWh from the grid?
Are you grid tied and on a feed in tarrif?  If so, what do they pay you per kWh?
Was the installation cost subsidised?

[mux]

The nice thing about Sweden in particular is that you've got a couple of big low-budget solar manufacturers like REC and Aurora that drive the prices down. Sweden has the lowest installation cost after Germany and Denmark.

I get sub-3 year payback times with my system in the Netherlands with only about 10% more sunlight than southern Sweden:

http://www.sapa-solar.com/images/annual-global-irradiation.gif

Is <3yr payback a measured result from an actual installation or a theoretical estimate? This far north the angle of the sun is pretty low during winter as well which I expect would be detrimental, there are many factors so it's hard to be sure what to expect (at least there is hardly any snow these days). But maybe I should look into it again.

It's now had a full summer's production, so I've got enough data to say it does actually stack up. I've got 1970Wp and produced 1220kWh so far over the last 7 months - expected to get just over 1500kWh this year. Next year, a tree that's severely obstructing the panels and casting a shadow around noon every day is going to be gone, so we expect about 1750kWh per year. The installation cost €1090 and our electricity cost is €0.21/kWh, so that's about €315/yr payback. We have net metering here, just like Sweden.

Payback is a lot worse for non net-metering countries; you generally get about €0.07/kWh, which means payback is about 9 years with the same kind of installation.

No subsidies, but I did buy the inverters second hand which saved us ~€200. I also did installation myself. This is a piece of cake nowadays, everything is standardized. There really is no need to have anyone do it for you unless you have a very tall roof or two left hands

Solar pays for itself anywhere with net metering now. This won't last of course, so if you're thinking about solar make sure to see for how long net metering is still allowed. Our government was about to abolish net metering starting in 2017, which prompted us to install our solar panels earlier this year. Now they actually extended this to 2020, so we'll definitely have our entire installation paid for in this period, even if something breaks in the meantime.

[SNGLinks]

In the UK, in order to qualify for the feed-in tariff, the solar power installation has to be done by an approved installer.

I had my system supplied and installed for free and the company who paid for that get the feed-in tariff. I have leased the space above my roof to them.
https://www.flickr.com/photos/snglinks/albums/72157637134670794

Originally my electric meter ran backwards when the sun was shining but the electricity company said that my meter was not compatible with solar power and changed it.

I wish now I had a hot water cylinder so I could store some of the energy.

[Seekonk]

Technically grid tie is an ideal solution. Politically grid tie is becoming a dead horse.  Utility payments for solar energy are going to drop and drop.  I divert excess PV solar to hot water.

[station240]

Other problem is most of the existing off grid solutions, are designed as DIY install kits with 12/24/48V batteries, and lower voltage solar arrays.
So using one of them in an existing grid system means rewiring the panels, with thicker cable as well.

I did come across this which takes 48V DC input
http://solar.schneider-electric.com/product/conext-xw-230v-50hz/
And the matching MPPT which converts <600V solar arrays into 48V DC
http://solar.schneider-electric.com/product/conext-mppt-80-600/

It seems to me the small scale off the shelf home storage solutions are either all in one bricks that include everything, or a mains connected battery which is really just a UPS (with obvious double conversion losses). I don't like the all in one solutions, especially as it makes in impossible to keep the expensive batteries somewhere cool, without taking the entire unit inside.

What is really needed is the ability to treat the battery bank as another variable voltage/amps input like the solar array is. Then you can just choose the battery capacity/voltage that suits your needs. Would require a proper standard to work properly.

Companies have made UPSs with modules, for the really huge units anyway. Need more power output, add a second inverter, battery banks are separate cabinets and you can have multiple, same for power input/switching/bypass. Why can't we have a scaled down version that lets you pick and choose what modules you want inside the big white box ?

Given the ongoing development in battery technology, the part most likely to be obsolete is the battery charger and any related BMS (battery management system). Batteries are crazy expensive at the moment, so the builds involving assembled technology (eg mail ordered kits) carry a risk of bricking the batteries, should you over charge/discharge them, let them get too hot, etc. One company recommends people new to offgrid power, buy cheap batteries to start with for this reason.

[CatalinaWOW]

Siting is even more important than region in determining solar payback.  I lived in Southern Arizona for years.  A wonderful area for solar.  But my home not so much.  Roof orientation about as bad as possible.  I could have built structures to orient panels better, but making them compliant with neighborhood association requirements would have dramatically added to costs.  Factors which made the house much more livable than many in the area were direct no-nos for solar.  Placement in a small valley limited morning and evening sun, so air conditioning requirements (the dominant electrical load in that region) were greatly reduced, but so was solar potential.  Deciduous trees provided summer shade further enhancing comfort, but hurting solar.

In addition to siting issues, many financial payback calculations make unwarranted assumptions about future costs.  All solar proponents argue that payback periods will be shorter as electricity prices rise.  I have been reading that argument for nearly 20 years now.  Nearly the life of a system installed when I first tried to justify it for myself.  While it does seem likely that it will happen sometime in the future, it is already twenty years later than earlier predictions, and could easily be another few decades away.  Installation of solar being one of the reasons.  You can't add capacity to a market without having a downward effect.