Usefulness of solar panels

After seeing a members experience with solar panels, I was wondering how well are they as an investment? Where I live in VA I should only get 4 hours of bright direct light then many more of half or less indirect light. Compaired to the kilowatt hour here and the price of them looks like it would take me 15 years before I break even. I have heard from folks who use RVs that they do generate power even at night and under street lamps, but would it make much of a difference to supplement your power in your house?

What about putting solar panels on an EV? Ive seen them on motor homes and RVs, but why not EVs?

I have a small system on my home, 24 volts @ 57 watts total power from 4 panels, 2 are 42 watt panels in series made by unisolar and 2 unknown manufacture 15 watt panels in series that is diode isolated from the other set of panles.
I justify them for emergancy power, the output is too low so suplement but only a very small amount of power, I light my kitchen with that system as well. My biggist limitation with the system is I whent with cheap batteries and they lost over 20% capacity when I did a discharge test, had to learn the hard way to not do that.
As it stands now I wish I had spent the money on a 400 watt wind turbine, that would have been more usefull more times of the year.
For a solar system to be usefull IMHO you need to have atlest a few kilowatts, skip the batteries(unless for emergancy power reasons) and go with a grid tie inverter.

Hey Cobb:

I power my whole cabin with solar and some wind. I'm way off grid. Solar panels work great, but you really only get meaningful power if they are in direct sunlight. They don't work off the moon or streetlights.

Batteries are the weak point. They rob efficiency, especially when they get old. And they require maintenance.

As Draco A. said, it's much more efficient to tie your panels directly to the grid. The general rule is a battery system produces power at about 30 cents per KWhr (this varies with the size of the system, its design and the type of equipment you use). Grid-tied, it gets down to half that.

You may never achieve a payback, depending on your cost of grid power, but there are still advantages: You become self-sufficient; your power is of a higher quality than that you buy over the grid; your power is more reliable (I've never lost power); it's better for the environment; and with an in-house digital meter, you learn exactly how much power you are using and wasting. I've found that for the same amount of utility (one hour of TV, x number of lumens, etc.) I need between one-half to one tenth the power that my friends in the city use to accomplish the same tasks. So even though I pay more per KWhr, I need much less to do the same task.

Bottom line: Solar works. And I live deep in a rainforest valley. But you have to design it correctly and rethink the way you use energy.

Josey

Solar power for a home will begin to make more and more sense as the cost of electricity goes up, and the cost per installed kW of solar panels goes down. Given that electricity now costs $0.18/KW-hr in NYC, solar may already make sense. I figured by covering the entire roof in solar panels I can generate on average more electric than we use. The weak link is how to store it. While it is fairly straightforward to tie an inverter into the breaker panel, and switch between grid and solar as needed, this still makes one dependent upon the grid when the panels aren't generating electricity. Storage via a bank of lead-acid batteries is expensive and inelegant. Eventually the batteries will need replacement which adds to the costs. Once a means of storing the surplus energy exists which lasts long enough to never need replacing (let's say at least 50 years) and costs no more than batteries, I think we will start seeing solar power installed in new homes as a matter of course. It will also gradually be retrofitted in older homes, replacing both the need to use grid electricity, and also to use fossil fuels for heating/hot water. I think the technologies to enable this to happen will be mature within a decade. We'll have far more efficient panels by then as well.

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What about putting solar panels on an EV? Ive seen them on motor homes and RVs, but why not EVs?


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I'm surprised this isn't already done. The problem is vehicle designers seem to have an all or nothing approach. If the solar cells can't supply 100% of the power requirements for the vehicle, they see no need for them. I think solar cells built into the roof, hood, and trunk of an EV can supply a good portion of the energy needed. If one uses the vehicle exclusively for short trips, it can likely supply 100% of the power by recharging the batteries while the car is parked. Even on longer trips, the solar cells can supplement the battery, and extend the range significantly. I really wish the automakers would give electric vehicles a second look in light of new battery and solar technologies. They are eminently more sensible than hybrids (which still have noisy, polluting engines) or even fuel cells (which must still carry dangerous, explosive fuel). The range problems of EVs are highly exaggerated. 99% of vehicle round trips fall within the range of current EVs. EVs that can partially or fully recharge when parked in the sun will extend their range even further.

Never considered emergency power, thats a whole new ball of wax. In that event they would be priceless, unless stolen. Of course I would need enough for useful power unless I use batteries, although it seems they are the weak link. Ihave heard from folks that over do it with solar panels to get more power out of less light or even a power booster.
Somehow it takes the voltage from the solar panels and goes from parallel to series to get you the most out of them before they produce nothing. Ive seen on homepower that many use a grid tie system to supplement their power, that seems like something i could do if the apartment folks would let me put some solar panels outside m south facing unit in the name of science. My power bill ranges from 18-54 bucks yearly.

Reason I ask about putting a solar panel or 2 on an EV is that I knew that is a long debate in the wheelchair world. Ive and others have always asssumed that for solar power to be effective on a wheelchair that use 1600 watts a day or 15 amps an hour would need solar panels that would look like a wing, weigh several hundred pounds and be in direct sunlight. Having an onboard 5 amp charger I have topped it off every now and then when it was low and what little time i get seems to do alot.

Well, one day someone tried it. They got 2 of those panels you stick in your dashboard of your car to top your battery off. He hooked both in series and to his batteries. He claims it has giving him an extra bar of energy on his 10 bar power meter.