PV Gap

Darryl Said:

is it possible to find out my gross electrical usage?

We Answered:

Sounds like you need a power meter to attach to your equipment. It will measure how much power, in Watts, it is generating. Take that reading and add it to the electric company power meter to get the total. Thank you for being green and Good Luck!

Leona Said:

Can we turn heat energy to electrical energy directly?

We Answered:

What you are asking about is not only possible, it has been in use in limited applications for a while. These devices are based on the Peltier–Seebeck and Thomson effects:
http://en.wikipedia.org/wiki/Peltier-See…

Thermoelectric generators have been used on deep space probes for several decades:
http://en.wikipedia.org/wiki/Radioisotop…

These devices use radioactive materials as a heat source. The Soviet Union also used similar devices to power remote beacons and lighthouses:
http://www.bellona.no/bellona.org/englis…

There are also small thermoelectric devices designed to work at lower temperatures for common applications:
http://www.dts-generator.com/gen-txe.htm

Katherine Said:

Do solar panels add to global warming?

We Answered:

As far as it goes, you're right: putting up a big black object increases the total amount of energy absorbed from the sun. But that's only part of the story.

If you didn't put up the solar panel, the same radiation would hit the earth. The earth already absorbs 2/3 or so of the energy that comes in (albedo .30), so adding even a perfectly black object increases it only by 50%.

But it's not even that much, because most of the extra energy absorbed is converted into electricity. Solar panels are about 10-15% efficient, so half of the extra energy is turned into electricity rather than heat.

Eventually it's put to use and turned into heat, but that heat was going to come from somewhere else anyway. (Even if it's just powering your DVD player, it turns into heat just the same as if you were using it to heat your house.) If you dig up a gallon of petroleum or fission a microgram of uranium, that's heat introduced into the earth's atmosphere. And these processes are inefficient: between generation and transmission you lose about 75% of the energy, meaning you've introduced 4 times as much energy into the atmosphere as you've actually used.

So with a solar panel, you add extra heat to the earth by about 25% of incoming solar radiation, but you've offset external costs by about 45% of incoming solar radiation. The net effect is to cool the earth.

And that assumes that the solar panel itself is perfectly black, which isn't the case. Real commercial solar panels have an albedo of about .35, which makes them more reflective than dirt and considerably more reflective than asphalt shingles, which have .03 albedo. In other words, even if you didn't actually use the solar panels for electricity, they'd be cooling the earth just by reflecting energy back into space more than your regular shingles.