Solar Cells on Homes

Factual Questions
21

[QUOTE=Napier]
That being said, solar cells are very nice for trickle charging batteries. They produce DC without any other electronics involved (I’m counting the cell itself as an electronic device). They produce fairly expensive power, on a capital outlay per watt basis, but can slowly charge batteries that are big enough to supply lots of power for shorter periods of time. And solar cells typically produce their power for most of the day but with unpredictable lapses due to clouds, shadows, and the like. Batteries deliver power whenever you want, if they have stored some. So solar cells and batteries are pretty perfectly complimentary to one another.
[/QUOTE]

Correct.

It should be kept in mind that, in a system comprising PV arrays and batteries, all of the electrical energy comes from the PV arrays; none comes from the batteries. (With the possible exception of the energy that was initially stored in the batteries when they were purchased.)

The analogy I like to use is a municipality’s water system. The wells are like PV arrays, and the water tower is like a battery. Water does not come from the water tower; it comers from the wells. The wells “trickle charge” the water tower. The tower is simply a device for storing energy (potential energy) and a quantity of water.

22

[QUOTE=Crafter_Man]
Well, *someone * had to pay for it. Sounds like the taxpayers did. :dubious: Hence your calculations should be based on $50K, not $15K. Plus maintenance and upkeep.

It’s doubtful I’ll ever install PV arrays. Grid power is just too damn cheap to justify it.
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How did you miss this sentence? “The pricing is higher than you estimated without state help”

That was my point. I said I thought **beowulff ** underestimated the cost of installation. We are still in the early adopter stage where various governments are providing huge incentives to make it worth wild. This is in the hopes of the breakthroughs that will actually make Solar Panels efficient and/or cheap enough to become a common and cost effective solution.

BTW: Maintenance is very minor and actually increases the life of your roofing. What upkeep were you thinking of? The panels are good for 20-25 years or more. The solid state AC-DC electronics should have a similar age and most systems do not have batteries.

23

[QUOTE=beowulff]
You need to sign up for a metering program. The utility will inspect your system for safety, and if it passes, will install a special bi-directional meter.

BTW, I’m a big fan of Solar PV, but selling electricity back to the utility is a sucker’s game. You are much better off sizing your system to handle your average load, and let the utility handle the peaks - the power you are producing is much, much more expensive than what the utility will pay your for it.
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Just so that I understand how a power grid works, I have a follow-up.

To sell back the power, you need an inspection and a bi-directional meter. Now I’m wondering, if you didn’t do all that, would the power grid still suck your extra power from you without paying you? Is there something inherent in the system or infrastructure that would allow or cause it to utilize the power from your generator?

Also, where there is a power outtage from a hurricane or something and you plug your generator into your home outlet, will it turn your neighbor’s lights on?

… sorry, these are just some questions I’ve always kinda wondered and this thread has reenaged my curiousity.

Also, am I even right that you can plug a generator into your home outlet to power you house in the first place? I believe I heard people do this but that it is unsafe for the house and for repairmen on the lines. I could have misremembered…

24

[QUOTE=Bear_Nenno]
Just so that I understand how a power grid works, I have a follow-up.

To sell back the power, you need an inspection and a bi-directional meter. Now I’m wondering, if you didn’t do all that, would the power grid still suck your extra power from you without paying you? Is there something inherent in the system or infrastructure that would allow or cause it to utilize the power from your generator?

Also, where there is a power outtage from a hurricane or something and you plug your generator into your home outlet, will it turn your neighbor’s lights on?

… sorry, these are just some questions I’ve always kinda wondered and this thread has reenaged my curiousity.

Also, am I even right that you can plug a generator into your home outlet to power you house in the first place? I believe I heard people do this but that it is unsafe for the house and for repairmen on the lines. I could have misremembered…
[/QUOTE]

Simple answer, to connect to the grid you need to pass inspection by at least the electric company and the state and in most places your township.

The power company is required to change the meter to one that flows in both directions.

The typical on grid setup only runs when the grid has power. This is to avoid the situation of feeding power into the grid and thus endangering the line-man that need to work on lines that should be dead.

There are solid state and electrical-mechanical systems that allow for the lock-out of the connection to the street and the ability to then use the power being generated. I will be installing some system like this in the next year or two. I would then be able to power my Refrigerator or Furnace depending on the time of year and some other select appliances and lights. I would of course on my own, shut off nearly every circuit breaker in the panel before switching to pure solar power.

As to the generator specific question, if you ever wish to power your home wiring and have a large enough generator to bother you should follow many extra safety precautions and the electric companies discourage this unless set up by a trained electrician that is following regulations.

*Basic list of instructions, please look for more detailed ones. *

  1. Secure the power from the street via the main breaker and the outside cut-off if you have one.
  2. Turn off all breakers in the panel (or pull all the fuses)
  3. Fire up the generator and feed the wiring. Check load.
  4. Choose a circuit with a very light load and turn it back on and verify everything is working correctly.
  5. Determine what kind of load your generator can actually support.

Note 1) You will need a cable with a male plug on each end to plug into the generator and an outlet that is hopefully near the panel.

Note 2) It is far simpler and safer to just run a few extensions cords and surge protectors from the generator to power what you consider vital.
Just to avoid the inevitable question, yes my system generates power even with up to 12"* of snow on it. The sun shines through the snow.
Added bonus, the panels heat up and the snow slides off on its own.
Slight Danger, when it comes down, it come down swiftly and it would not be fun to be caught under it. I strongly suspect it be dangerous to a brittle senior.

Jim

  • Possible more than 12", I have never had more than 12" since I installed my panels.
25

[QUOTE=Bear_Nenno]
How do you sell power back to the electric company? Do you have to register to do that or does it happen automatically when you hook up some type of generator? If I have a diesel generator in my basement and I plug it into the electrical outlet, will I get a check from my electric company? If I didn’t live in Florida, I mean.
[/QUOTE]

Tallahassee has a net metering program. Just because it’s not statewide doesn’t mean your city doesn’t have a way to net meter if you go solar.

Of course, Tallahassee’s utilities are owned by the city and are not part of FPL or whatever power companies run the rest of the state.

26

[QUOTE=Dogzilla]
Tallahassee has a net metering program. Just because it’s not statewide doesn’t mean your city doesn’t have a way to net meter if you go solar.

[/QUOTE]

Ah, but then I couldn’t have a basement in which to keep the generator, now could I? :wink:

27

[QUOTE=Bear_Nenno]

Also, am I even right that you can plug a generator into your home outlet to power you house in the first place? I believe I heard people do this but that it is unsafe for the house and for repairmen on the lines. I could have misremembered…
[/QUOTE]
You would have to disconnect from the grid to plug your generator into your buss panel and you should have a certifiable connection before you do it.

28

Someone correct me if I’m wrong, but the way I understand things to work in CA is:

The power company will buy back electricity from you, but only to offset your own use. They essentially give you a rebate on your bill, but if you generate more energy than you use, they don’t compensate you for it-- they pay you up to the amount you used and then say thank-you-very-much for the rest. (Actually, they don’t say anything-- they just take it.)

29

[QUOTE=Bear_Nenno]
Ah, but then I couldn’t have a basement in which to keep the generator, now could I? :wink:
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Erm, I don’t get it. Why do you need a basement or a generator for solar panels on your house?

The solar panel people put a net meter and a power transformer thingy on the side of your house. No generator involved, which would be redundant and pointless.

30

[QUOTE=Dogzilla]
No generator involved, which would be redundant and pointless.
[/QUOTE]

So, it’s night time and the utility power goes out in a storm. Now, who thinks a gen is redundant and pointless?

31

[QUOTE=Dogzilla]
Erm, I don’t get it. Why do you need a basement or a generator for solar panels on your house?
[/quote]
I made this statement:

If I have a diesel generator in my basement and I plug it into the electrical outlet, will I get a check from my electric company? If I didn’t live in Florida, I mean.

You countered that statment by giving examples of cities in Florida where my scenario should be possible. You assumed that because those cities offer net metering, that all the conditions of my statement were met. But the other half of my statement was “a generator in my basement”.

The “joke” is that Florida homes don’t have basements. So regardless of which Florida cities have net metering, I can’t have a generator in my basement if I live in Florida because we dont have basements.
That’s all. . . carry on.

32

[QUOTE=John Mace]
Someone correct me if I’m wrong, but the way I understand things to work in CA is:

The power company will buy back electricity from you, but only to offset your own use. They essentially give you a rebate on your bill, but if you generate more energy than you use, they don’t compensate you for it-- they pay you up to the amount you used and then say thank-you-very-much for the rest. (Actually, they don’t say anything-- they just take it.)
[/QUOTE]

I cannot verify that for California, but what you describe will vary state by state and even company to company.

In my case if I generate more than I use, I get credits towards future bills. At this point I am not aware of any way to cash out said credits. However as I use more than I generate, this has not been an issue to think about yet.

Jim

33

[QUOTE=Bear_Nenno]
I made this statement:

If I have a diesel generator in my basement and I plug it into the electrical outlet, will I get a check from my electric company? If I didn’t live in Florida, I mean.

You countered that statment by giving examples of cities in Florida where my scenario should be possible. You assumed that because those cities offer net metering, that all the conditions of my statement were met. But the other half of my statement was “a generator in my basement”.

The “joke” is that Florida homes don’t have basements. So regardless of which Florida cities have net metering, I can’t have a generator in my basement if I live in Florida because we dont have basements.
That’s all. . . carry on.
[/QUOTE]

Oh! Er. I got the joke about no basements… I just missed the part about if you plugged your generator into… :smack: Got it. Carry on.

My response was targeted toward serious inquiries about net metering with solar panels… not generators. :wink:

34

[QUOTE=Q.E.D.]
So, it’s night time and the utility power goes out in a storm. Now, who thinks a gen is redundant and pointless?
[/QUOTE]

I was thinking, if I had solar panels – forgetting the part about needing sufficient battery storage capability – why would I need a generator, if my roof is my power plant. A generator *would *be redundant if you shelled out the extra sheckels for batteries.

Short answer: Erm, yeah. I have a fusion generator in my backyard. J/K :: d & r ::

35

[QUOTE=Bear_Nenno]
I made this statement:

If I have a diesel generator in my basement and I plug it into the electrical outlet, will I get a check from my electric company? If I didn’t live in Florida, I mean. …
[/QUOTE]

On the generator, I missed one hopefully obvious fact. You cannot run more amps to your house via an outlet than the outlet, its wire and breaker are rated.

So again, you are far better off just running a series of extension cords and surge protectors directly from the generator.

Large generators, especially ones that are in “non-existent Florida basements” are hard wired in the system on their own breakers and have to have excellent exhaust run. People do kill themselves running generators inside of basements via carbon monoxide poisoning.
**Any other Solar Panel questions? **

I am always happy to answer these.

Jim

36

[QUOTE=What Exit?]
Your friends are 100% dead wrong. I have a 6700 Kw system on my roof. In simplest terms, during the day I sell power to the power company and at night I buy it back. I am part of the overall electrical grid and I have no batteries in my system at all.

If my system was larger I would actually be a net seller like one of my co-workers. Instead my lowest bill for the month has been $19.

Your EE friends do scare me a bit if they somehow think ‘electricity from solar power can only be used to trickle-charge batteries’.

Perhaps they should read more or enter a new field of study. :wink:

Jim
[/QUOTE]

I am surprised by that capacity. You know your system best of course, but you really have a 6.7megawatt solar generator on your roof? And you have to buy power from the power company? Seems like a lot. Is there something I am missing?

37

[QUOTE=rbroome]
Is there something I am missing?
[/QUOTE]

Post #10, for openers.

38

[QUOTE=rbroome]
I am surprised by that capacity. You know your system best of course, but you really have a 6.7megawatt solar generator on your roof? And you have to buy power from the power company? Seems like a lot. Is there something I am missing?
[/QUOTE]

Yes, the rest of the thread where is was pointed out that I mistyped. :wink:

It is only 6700 watts.

39

[QUOTE=Bear_Nenno]
Also, where there is a power outtage from a hurricane or something and you plug your generator into your home outlet, will it turn your neighbor’s lights on?
[/QUOTE]
Yes, depending on the exact connection from your house. One safety hazard in the post-Katrina clean-up was downed power lines with live electricity: even though the utilities had already shut off power to all broken lines, home generators plugged into wall outlets could power up the lines outside of the home.

40

Not to pile on too much, but I’ve already done the calculation: the total solar energy falling on a U.S. football field is about 7.3 MW. So that’d definitely be a big roof. :slight_smile: