Sustainability and renewable energies – a critical look at photovoltaics

The current status of photovoltaic modules from wafer‐based Si and thin films of Si, CuInGaSe₂ (CIGS), CdTe and III–V compound semiconductors in terms of efficiencies and market volumes is shortly summarized and evaluated with respect to sustainability. We discuss the critical raw materials such as gallium, indium and germanium. These materials are either incorporated into the absorber layers or used as substrate materials, i.e. Ge in the case of III–V semiconductor based cells. On a 100 GW per year production level the availability of indium and tellurium will limit the growth of the respective photovoltaic technology. Alternative materials are on the horizon, such as the kesterite‐type materials which offer the possibility to replace In and Ga in CuInGaSe₂, but it may take a long period of time for modules of these materials to reach the production‐level efficiencies of today's established technologies. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)