From Scientific American:
It takes power to make power—even with a solar grand plan. From the mining of quartz sand to the coating with ethylene-vinyl acetate, manufacturing a photovoltaic (PV) solar cell requires energy—most often derived from the burning of fossil fuels. But a new analysis finds that even accounting for all the energy and waste involved, PV power would cut air pollution—including the greenhouse gases that cause climate change—by nearly 90 percent if it replaced fossil fuels.
Environmental engineer Vasilis Fthenakis, a senior scientist at Brookhaven National Laboratory in Upton, N.Y., and his colleagues examined the four most common types of PV cells: multicrystalline silicon, monocrystalline silicon, ribbon silicon and thin-film. (Other contenders, such as amorphous silicon or superefficient multijunction cells were excluded for lack of data or lack of widespread application to date.) Even taking into account the low efficiency of thin-film solar cells or the energy needed to purify silicon for the other types of PV, all proved to entail significantly fewer emissions in their entire life cycle than the fossil fuels needed to produce an equivalent amount of electricity....MORE