Canada decided to investigate air as the transfer medium to remove heat from PV arrays, represented by Conserval’s SolarWall transpired solar collector, while most of the European members focused on liquid heat removal. Rather than develop a new PV thermal panel, Conserval took the approach of combining commercially available PV modules on top of the transpired collector and utilizing the unique air balancing features of the transpired collector to remove heat from the back of the PV array. In essence, the PV panel becomes a back pass solar air collector with the PV cells acting as the solar heat absorber with ambient air passing around and behind each PV module, removing heat and then the heated air enters the perforations in the transpired panel. This concept allows for heat removal from most PV modules currently available on the market and avoids the lengthy delays associated with developing a new PV panel and obtaining the associated electrical approvals.

The trend in PV installations has been to use larger PV modules. To obtain data that is representative of the PV systems currently being installed, popular models from three manufacturers were chosen. It is realized that the thermal performance may not be optimized but the objective was to determine the amount of heat that could be recovered from these readily available modules.

Two test labs participated in the PV thermal air tests, Canada’s National Solar Test Facility (NSTF) located in Mississauga Ontario and the Danish Technological Institute (DTI) located in Taastrup Denmark.