This project compares all of the new photovoltaic technologies that are approaching commercialisation. Eleven technologies are directly compared using 11 sub-arrays. There will be two parallel project sites, with the same 11 sub-arrays, at Oxford and in Mallorca, thus also comparing very different climatic conditions. This project is the first direct comparison of all the emerging photovoltaic (PV) technologies sited at the same location on retrofit building arrays. It will provide valuable independent comparative data to the industry and to the user, that will enable informed choice of photovoltaic technology for a given application. (C) 2001 Elsevier Science B.V. All rights reserved.