View Full Version : Do solar panels cool down the planet?
01-12-2003, 01:00 AM
If solar panels take solar radiation (heat) and convert it to electricity, do they reverse global warming, or do they just stave off the heating that would have occurred had that radioation not been absorbed?
01-12-2003, 01:22 AM
I don't know too much about how they work but I do know that the panels absorb the light energy that would normally be hitting the ground. That particular area wouldn't be heated as much as normal but as far as the earth, the amount of heat loss I would say couldn't be noticed.
01-12-2003, 01:39 AM
As I understand it, energy is never lost. It's simply converted into other forms.
The solar panels absorb the energy and keep it there, adding to the energy-total here on earth. In addition, I think solar panels reflect less light than the ground would normally, so they may actually be -adding- to the energy total of the earth instead of subtracting...
Granted, it's been a long time since I even looked into things like that, so I could be completely wrong :)
01-12-2003, 01:44 AM
They may be adding to the total amount of energy on earth but its transferred to electrical energy. Regarding the temperature of the earth, the thermal energy that would have been partially reflected off the ground would not be able to partly be bounced back due to greenhouse gasses, so (IANAE) I think it could *SLIGHTLY* lower the amount of thermal energy in our system.
I say slightly because I doubt it's even large enough to concievably measure.
all IMHO, of course, I may be wrong.
01-12-2003, 02:44 AM
The most important factor is the relative reflectivities of the solar panels vs. the ground, considered over all types of radiation that normally hits the earth.
Any energy that would normally be absorbed as heat by the ground, but is converted to electrical energy by the solar panels, will eventually became heat anyways, as electrical circuits are not perfectly efficient (and the waste is always in the form of heat).
01-12-2003, 11:05 AM
Yeah, it's a crock, but ya gotta love the image: Carl Sagan warning the Earth's citizens about The Solar Panel Winter!:D
Disclaimer: I honor and respect Carl Sagan and his memory. He's just the first guy I know of who used the phrase "nuclear winter" in public.
01-12-2003, 11:09 AM
Eventually, all the electrical energy produced by the solar panels will end up as heat energy, after it is used to perform work. In that solar panels absorb some energy that would have otherwise been reflectd into space, the net effect is that the use of solar panels increases the thermal energy in the global system.
01-12-2003, 11:16 AM
Anything converted to electricity is eventually converted to heat (maybe somewhere else), so the only question is whether solar panels absorb more sunlight than whatever they are replacing. If I had solar panels on my roof, it would replace black asphalt shingles which must absorb pretty much all the light (however, they are also efficient at reradiating it during the night). The solar panels are presumably made as efficient as possible in absorbing the sun's radiation so are likely similar to asphalt shingles in that respect. On the other hand, they send the energy off as electicity, so should be cooler and thus radiate less energy during the night. So on balance, there is very likely a slight increase in solar heating of the planet if you have solar panels, but it is much too small to have any noticeable effect.
01-12-2003, 12:59 PM
The energy collected by solar panels is totally negligible in the grand scheme of things but, if anything, Solar panels would *heat* the planet as they absob more energy than the ground which is a bit more reflective. It isn't going to make any difference though.
What about solar panels displacing electricty generated by other means?
The above posts assume that the electrical energy generated adds to total energy consumtion, i.e. powers an additional application using energy. That applies to a site off the electrical grid where, absent solar panels, people would have foregone the use of whatever device the solar panels power instead of e.g. running a diesel genset.
If the site is the grid, the electrical energy generated by the panels displaces an equal quantity of electrical energy generated in the largest part from fossil fuels/nuclear power. I don't know about the efficiency of nuclear plants but fossil fuel plants generate 1.5-4 times as much heat as electricity (for electrical efficiencies of 20 to 40%)
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