Abstract:
Hybrid photovoltaic/thermal (PV/T) devices can simultaneously generate thermal and electrical energy, but have been limited to low temperature applications. This is done to avoid performance degradation of the PV cell at high temperatures. While the low temperature approach limits PV losses, it would be desirable to develop concentrating photovoltaic/thermal (CPV/T) systems which operate at higher temperatures where the thermal energy can be utilized for electricity production. In addition to using more of the sunlight, these systems may help realize low costs as well as dispatchability through thermal energy storage. Presented here are two primary configurations: the first where the PV cell and thermal system are decoupled, and the second where the PV cell acts as the high temperature absorber. The efficiency of these systems and their ratio of thermal to electrical energy produced are reported as a function of architecture, cell bandgap, and thermal system peak temperature. The studies provide a basis to understand and compare the performance of CPV/T at different operating conditions and architectures. The results indicate that the configurations that utilize recovery of waste heat off the PV cell can achieve the highest efficiency at low concentration ratios, but it remains to be seen if PV cells can survive the temperatures necessary. The thermally decoupled case is attractive in terms of efficiency and operating temperature of the PV cell, but requires significantly higher concentration ratios. Both configurations can achieve exergetic efficiencies exceeding 40% and greater than 50% of the solar energy converted to dispatchable thermal exergy.
