Life-cycle assessment of photovoltaic modules: Comparison of mc-Si, InGaP and InGaP/mc-Si solar modules

A higher conversion efficiency of photovoltaic modules does not automatically imply a lower environmental impact, when the life-cycle of modules is taken into account. An environmental comparison is carried out between the production and use phase, except maintenance, of an indium-gallium-phosphide (InGaP) on multicrystalline silicon (mc-Si) tandem module, a thin-film InGaP cell module and a mc-Si module. The evaluation of the InGaP systems was made for a very limited industrial production scale. Assuming a fourfold reuse of the GaAs substrates in the production of the thin-film InGaP (half) modules, the environmental impacts of the tandem module and of the thin-film InGaP module are estimated to be respectively 50 and 80% higher than the environmental impact of the mc-Si module. The energy payback times of the tandem module, the thin-film InGaP module and the mc-Si module are estimated to be respectively 5.3, 6.3 and 3.5 years. There are several ways to improve the life-cycle environmental performance of thin-film InGaP cells, including improved materials efficiency in production and reuse of the GaAs wafer and higher energy efficiency of the metalorganic chemical vapour deposition process. Copyright (C) 2003 John Wiley Sons, Ltd.