Performance analysis and yield assessment of several uncovered photovoltaic-thermal collectors : results of field measurements and system simulations

A PVT collector combines a PV module with a solar thermal absorber and produces electricity and heat. Interest in PVT systems is growing, since these potentially generate more energy per m2 than PV-only systems. Furthermore, a large share of the residential energy use consists of heat. Within the Dutch project WenSDak, a consortium of eight companies and three knowledge institutes developed five different PVT concepts and evaluated their thermal and electrical performance. In this paper, we focus on three types of uncovered PVT collectors. There is a large difference between the measured thermal performance of the three different collectors. These differences can be explained by the PVT collector design. The absorption of all PVT modules is quite good (0.9 – 0.94). A good heat conduction from the PV cells to the absorber leads to a high peak collector efficiency, while insulation at the back of the PVT module improves the performance at higher temperatures. Performance of some collectors can be improved by e.g. heat conducting paste, however, this is also more expensive. System simulations with PVT as part of a solar heating system are carried out in TRNSYS and will yield valuable information on the annual yield for a specific system.