The thermal stress on building-integrated photovoltaic modules (BIPV) in Espoo, Finland, was studied with field-testing of amorphous silicon modules. Based on these results, the thermal stress at two other European locations (Paris and Lisbon) was estimated. The estimation procedure entailed thermal modelling of heat transfer in the facade with meteorological data as input. The results indicate that the thermal stress on BIPV modules in Lisbon is, in this case, approximately 50% higher that in Espoo and between 80 and 200% higher than in Paris, depending on the activation energy of the degradation process. The difference in stress between a BIPV module and a free-standing module in Espoo was 50-200%. Copyright (c) 2006 John Wiley & Sons, Ltd.