PV Gap

Katrina Said:

How effective is solar power?

We Answered:

Comment to "Ed" added...

There are two main types of solar power. One produces electricity, the other produces heat.
The electrical type are called "photovoltaics", the heat type are "thermal".
Photovoltaics are not presently very efficient, converting less than 15% of the suns energy to electricity, but by the time you build, they should be better, and cheaper. Thermal solar is much more efficient, especially if you use it to heat your water, because the system runs all year. Home heating is not as good, because winter is not a good time to collect solar. When you design your house, you can take advantage of "passive" solar, which is basically putting a lot of good windows on the south side (or north side if you are south of the equator!) and letting the winter sun shine in. These windows need to be very good, or have an insulator to cover them at night and cloudy days or they will gain energy all day, only to lose all of it at night.

As far as your house goes, it's not so much a matter of how big it is, as how well insulated it is. If you "super insulate" it, you will need very very little heating or cooling energy.
The other cost you will have is for things like computers, refrigerators, TVs, sound systems, lights, fans, cooking equipment and water heating. By picking the most efficient, you can reduce the size of the photovoltaic system you would need, and using solar water heating will handle 50% of the yearly amount with present technology for about $3500. A photovoltaic system to handle all your electrical needs would be quite expensive now, in the $10,000 to $20,000 range, but that cost will continue to fall, and by the time you build it should be closer to $5000.


Hey Ed....I don't know when you bought your system, or what other costs were associated with it...but 6KW systems don't cost 40K anymore...this from Solar Today "A 25-year warranty accompanies the Sharp panels. In 2003, we paid $18,000, which included the eight batteries, two inverters, hardware, 6,000 watts of solar panels and labor."....and King solar sells a "whole house" package for $11,000... but they don't say how big it is. The average home in California uses about 7000 KW per month...so to get that much is going to be more expensive. Our young friend here is thinking ahead. If a house is located right and designed well, then the most efficient appliances and lighting is selected, it would be easy to live well on half that 7000KW.


Good luck, and good thinking!