Life cycle assessment of thin-film GaAs and GaInP/GaAs solar modules

This paper presents an environmental comparison based on life cycle assessment (LCA) of the production under average European circumstances and use in The Netherlands of modules based on two kinds of III–V solar cells in an early development stage: a thin‐film gallium arsenide (GaAs) cell and a thin‐film gallium‐indium phosphide/gallium arsenide (GaInP/GaAs) tandem cell. A more general comparison of these modules with the common multicrystalline silicon (multi‐Si) module is also included. The evaluation of the both III–V systems is made for a limited industrial production scale of 0·1 MWp per year, compared to a scale of about 10 MWp per year for the multi‐Si system. The here considered III–V cells allow for reuse of the GaAs wafers that are required for their production. The LCA indicates that the overall environmental impact of the production of the III–V modules is larger than the impact of the common multi‐Si module production; per category their scores have the same order of magnitude. For the III–V systems the metal‐organic vapour phase epitaxy (MOVPE) process is the main contributor to the primary energy consumption. The energy payback times of the thin‐film GaAs and GaInP/GaAs modules are 5·0 and 4·6 years, respectively. For the multi‐Si module an energy payback time of 4·2 years is found. The results for the III–V modules have an uncertainty up to approximately 40%. The highly comparable results for the III–V systems and the multi‐Si system indicate that from an environmental point of view there is a case for further development of both III–V systems. Copyright © 2006 John Wiley & Sons, Ltd.