ABSTRACT
The time for the energy "embedded" in the materials and manufacture of a PV system to be "paid back" during use is an important measure of environmental viability. Energy payback times were estimated for PV systems using lens and mirror concentrators, and compared with those for multicrystalline (mc-Si )and amorphous (a-Si) silicon flat plates, using solar data for three contrasting sites. Both concentrators gave significantly shorter payback times than the mc-Si flat plate at all sites (1.0 to 2.7 years, compared with 2.1 to 3.6 years), and shorter or comparable times to the a-Si flat plate. Carbon dioxide payback times are very similar to those for energy. The systems will save between 1.5 and 3 tonnes of carbon dioxide per aperture over a lifetime of 20 years. Key assumptions are discussed in the paper.
