Wondering which solar technology has the smallest environmental footprint? In recent years new photovoltaic technologies have nearly doubled the efficiency of solar cells. Yet production methods, whether from silicon, metal, or other material, raise doubts about their environmental friendliness. For example, purifying and producing silicon uses a lot of water and energy, whereas refining zinc and copper ores to get cadmium, telluride, and other elements creates metal emissions and an energy sink.
Now Environmental Science & Technology calculates the impact. They've released a life-cycle assessment of some of the leading photovoltaic technologies. Some appear better than others. You can read the pdf here.The study notes that, even with the costs, the benefits of replacing gas- and coal-fired grids with photovoltaics cut greenhouse & particulate emissions 8998%. Rooftop panels reduce emissions even more due to the resulting decrease in transmission lines and other infrastructure.
The winner? Thin-film cadmiumtelluride (CdTe) photovoltaics—with more efficient energy conversion and lowest costs.