Environmental Assessment of Photovoltaic Technologies

Production of electricity in solar cells enables a flowing energy resource, sunlight, to be brought into the technological system. Although only small adverse environmental effects result from the operation of solar cells, production and sometimes disposal have more environmental impact. The impact is described for a number of types of solar cells, in various applications, and the technology is evaluated from an environmental point of view, as compared with power production fom fossil fuels and nuclear power. A life-cycle perspective is adopted, although the study is not a quantitative life-cycle assessment. Crystalline silicon (c-Si) and amorphous silicon (a-Si) cells, copper-indium-diselenide (CIS) and cadmium-telluride (CdTe) cells, are considered. c-Si cells require considerable amounts of energy during production. Both CIS and CdTe cells contain cadmium, but CIS to a smaller extent. Indium is a very scarce resource. All the technologies except CdTe involve use of toxic and/or explosive gases during production. Solar cells are used in consumer products such as pocket calculators. The energy production in this application is marginal. They may consitute an environmental problem if they contain cadmium or are used in connection with cadmium containing batteries. Stand-alone systems often require batteries, which contain heavy metals. They may contribute to electricity generation to some extent. They may have a positive influence on aesthetic natural values through reducing the need for power transfer to single, remote power consumers. Large scale electricity production in grid-connected systems are possible in a longer time perspective, and thus the assessment has a larger degree of uncertainty. The systems could make a large contribution to electricity production. However, over a certain production capacity, this requires energy storage, e.g . in water reservoirs or as hydrogen. Large scale electricity production in solar cells is assessed, from an environmental point of view, to be a better alternative than nuclear or fossil fuel based power generation.