Solar doesn't emit CO2, murcury or other polutants like sulfer dioxide to produce electricity it just uses the photons from the sun to displace the electrons in the semiconductive solar material.
Other ways of producing electricity does produce these nasty polutants which produce smog, acid rain and the murcury as you can imagine isn't very good especially when it comes back down in the rain and contaminates the soil and rivers which in turn contaminates our food supply. And with nuclear you end up producing large amounts of highly radioactive material that stays radioactive for thousands of years.
Although producing solar panels takes lots of energy the energy can be produced with renewable energy and giving that soloar panels last around 40yrs you get back more energy than you use to produce them.
Newer solar advances are also coming with much greater efficiency such as the ones used on the mars rovers (check out the nasa website they may have good details) which are multi layer cells which are capable of using more of the light spectrum hence they can produce more power with less cells.
Solar can also be used to produce other fuels like hydrogen by using electrolysis to separate water into hydrogen and oxygen which then can be burned cleanly in cars or other appliences and it can be used in fuel cells.
the main setbacks with solar are the cost which will go down as production increases (see what germany has done) and the space needed for the solar panels but if roof tops are used alot of that space issue is overcome.
There is also solar in the way of solar furnaces which are large mirrors which focus the suns rays on water creating steam to turn a generator turbine and produce electricity nevada is currently installing one of these furnaces close to the las vegas strip to produce clean energy.
You may be able to get some extra credit by having your class go to a click to donate site which uses advertising to give free donations like free solar power with each click. See the following sites they will also have more info about solar www.solarsite.net and www.stopglobalwarming.care2.com and www.ecologyfund.com