Author Topic: EEVblog #484 - Home Solar Power System Installation  (Read 66260 times)

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Offline IanB

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #125 on: June 17, 2013, 11:48:52 pm »
The idea is to avoid having hazardous voltages if an area of the grid which is disconnected, for example for maintenance.

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

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

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #126 on: June 17, 2013, 11:49:46 pm »
A normal inverter will always shut down operation when the AC signal is lost. Some have an "island" mode in which they can still power the house

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

Offline gxti

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #127 on: June 18, 2013, 12:12:45 am »
Yes, obviously it works somehow.  I have done some Googling, I found lot of references to IEEE 1547 which is the standard that describes "distributed" power generation signalling or something like that.

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

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

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

Offline Stonent

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #128 on: June 18, 2013, 01:52:05 am »
In this case the solar installation would be providing power to you ate 20c/kWh, rather than into the grid at 6c/kWh so it has its uses, particularly at weekends.

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

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

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

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

The larger the government, the smaller the citizen.
 

Offline Stonent

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #129 on: June 18, 2013, 02:01:28 am »
Since we're on the subject of breaker boxes, here's what a typical US installation looks like:





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

Here's a typical analog meter:



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

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



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

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #130 on: June 18, 2013, 02:14:42 am »
Since we're on the subject of breaker boxes, here's what an atypical US installation looks like:


There, fixed that for you  ;)
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Offline DrGeoff

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #131 on: June 18, 2013, 02:15:41 am »
In this case the solar installation would be providing power to you ate 20c/kWh, rather than into the grid at 6c/kWh so it has its uses, particularly at weekends.

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

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

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

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

Was it really supposed to do that?
 

Offline mtdoc

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #132 on: June 18, 2013, 02:26:38 am »

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

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

Offline digsys

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #133 on: June 18, 2013, 02:28:23 am »
Quote from: DrGeoff
If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times. 
I know people who do just that (with the cheap 2nds battery banks). In some cases they are still locked in at the original FIR, so
will never pay for power. It is illegal, and IF you get caught  .... interestingly, it has been suggested as a solution by the providers !!
If they do it, it's legal.
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Offline DrGeoff

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #134 on: June 18, 2013, 02:34:37 am »
Quote from: DrGeoff
If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times. 
I know people who do just that (with the cheap 2nds battery banks). In some cases they are still locked in at the original FIR, so
will never pay for power. It is illegal, and IF you get caught  .... interestingly, it has been suggested as a solution by the providers !!
If they do it, it's legal.

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

Offline Stonent

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #135 on: June 18, 2013, 03:02:19 am »
Since we're on the subject of breaker boxes, here's what an atypical US installation looks like:


There, fixed that for you  ;)

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

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

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #136 on: June 18, 2013, 03:50:13 am »
Welcome to Horse-trailer, where the energy companies can root your boot however they like.
Peak is 47.7c/kWh curently when 'smart' meters are installed, overall this seems to average to about 25c/kWh. This is about to increase another 1.5% next month. If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times.
Gas prices are also being increased significantly, next month by around 8.5%.

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

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

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

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

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

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

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

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #137 on: June 18, 2013, 03:52:03 am »
If I had a gas supply I'd be looking at one of these ceramic fuel cell generators.
http://www.cfcl.com.au/bluegen/

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

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #138 on: June 18, 2013, 03:55:35 am »
Welcome to Horse-trailer, where the energy companies can root your boot however they like.
Peak is 47.7c/kWh curently when 'smart' meters are installed, overall this seems to average to about 25c/kWh. This is about to increase another 1.5% next month. If offline storage was cheap it would make sense to pull power during off-peak (at 11c/kWh) and use it during peak times.
Gas prices are also being increased significantly, next month by around 8.5%.

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

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

Offline Stonent

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #139 on: June 18, 2013, 03:56:49 am »
If I had a gas supply I'd be looking at one of these ceramic fuel cell generators.
http://www.cfcl.com.au/bluegen/

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

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

Mr Fusion...when will you get here?
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Offline IanB

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #140 on: June 18, 2013, 03:58:37 am »
Atypical because it looks tidy, or atypical for some other reason?

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

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #141 on: June 18, 2013, 05:21:48 am »
I just can't justify going PV yet,  instead I do what I can to cut down on the bill in other ways.  I've been running solar hot water for years,  my hot water heater is turned off at the breaker 3/4 of the year and I have crazy hot water all the time.    My brothers and I did however just put in a 500w solar well for the parents small farm to water some crops that are too far from the main well.   It's amazing how effective it ended up being.   

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

Jeff
 

Offline GeoffS

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #142 on: June 18, 2013, 08:53:54 am »
I've friends nearby who are about to make a decision on solar so I've pointed them at the video.

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

Here's a photo of the main meter box.
 

Offline Ed.Kloonk

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #143 on: June 18, 2013, 09:12:37 am »
Atypical because it looks tidy, or atypical for some other reason?

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

I agree. It looks pleasing.

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

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

 

Offline EEVblog

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #144 on: June 18, 2013, 09:35:33 am »
I got that drop just after 2pm again today, so must be shading form the nearby houses and/or trees with the low sun angle in winter.
Will have to do another roof timelapse to capture what's happening.
 

Offline Pat Pending

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #145 on: June 18, 2013, 09:45:16 am »
http://spacestationlive.nasa.gov/displays/spartanDisplay1.html

Of out curiosity, this link to the ISS live data feed displays the power output from each of the panels on the station.
On the 2nd info page it shows that they are using ammonia cooling.
« Last Edit: June 18, 2013, 09:48:12 am by Pat Pending »
 

Offline digsys

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #146 on: June 18, 2013, 10:00:49 am »
Quote from: DrGeoff
What part of this could be considered illegal? You are consuming power during off peak times and generating power from the stored energy during peak times. Provided it is installed in accordance with the required standards then it is unliely to be illegal. What is illegal is using the OPHWS feed to pull energy (at around 7c/kWh instead of 11c) for storage and later use. 
It is illegal to use "cheap" power to charge up a battery (or other storage bank) - then resell it back to them at peak time.
Note: This is on viable if your FIR is much greater than the "cheap" rate. Ring them up and say you're doing it :-)
It's NOT the same as "selling" solar-power or excess EV storage (IF that ever becomes feasible)
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Offline DrGeoff

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #147 on: June 18, 2013, 10:18:14 am »
Quote from: DrGeoff
What part of this could be considered illegal? You are consuming power during off peak times and generating power from the stored energy during peak times. Provided it is installed in accordance with the required standards then it is unliely to be illegal. What is illegal is using the OPHWS feed to pull energy (at around 7c/kWh instead of 11c) for storage and later use. 
It is illegal to use "cheap" power to charge up a battery (or other storage bank) - then resell it back to them at peak time.
Note: This is on viable if your FIR is much greater than the "cheap" rate. Ring them up and say you're doing it :-)
It's NOT the same as "selling" solar-power or excess EV storage (IF that ever becomes feasible)

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

Offline N TYPE

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #148 on: June 18, 2013, 10:26:18 am »
As an electrician I have to say that having the customer standing watching you work is the worst..
Let alone having the home owner filming you while you work and blogging about it.. Nightmare :P
 

Offline BillyD

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Re: EEVblog #484 - Home Solar Power System Installation
« Reply #149 on: June 18, 2013, 12:17:34 pm »
As an electrician I have to say that having the customer standing watching you work is the worst..
Let alone having the home owner filming you while you work and blogging about it.. Nightmare :P

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

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


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