Outdoor Operating Temperature of Modules in BIPV and BAPV Topologies

Photovoltaics (PV) are promoted as an environmentally friendly alternative to carbon intensive energy sources, however, typical installations require expansive land-use. Building-integrated and building-applied photovoltaics (BIPV and BAPV) minimize this impact by use of pre-existing and non-productive surfaces for module installation. In these environments higher operating temperatures are expected because of reduced rear-side ventilation, which will have an impact on performance both instantaneously and in the long-term (i.e. reliability). A test station of 18 modules mimicking typical topologies for BIPV and BAPV was constructed in Neuchâtel (Switzerland) to monitor the thermal behavior of modules for validation of temperature predictions and modelling of degradation. Back-of-cell and back-of-module temperatures were measured by integrated thermocouples, and three factors were explored, including 1) module glass thickness (3.2-mm and 6-mm); 2) insulation (insulated, close-roof, and open-rack); and 3) inclination (0°, 45°, and 90°). Insulated and slope-mounted modules experienced the highest average temperatures and diurnal temperature differences across the year, though seasonal variations and other nuances were observed. Once long-term data sets are obtained, they will be utilized to validate temperature calculation models and model thermal and photothermal degradation of PV modules.