Analysis of Thermal Losses for a Variety of Single-Junction Photovoltaic Cells: An Interesting Means of Thermoelectric Heat Recovery

Exploitation of solar energy conversion has become a fundamental aspect of satisfying a growing demand for energy. Thus, improvement of the efficiency of conversion in photovoltaic (PV) devices is highly desirable to further promote this source. Because it is well known that the most relevant efficiency constraint, especially for single-junction solar cells, is unused heat within the device, hybrid thermo-photovoltaic systems seem promising. Among several hybrid solutions proposed in the literature, coupling of thermoelectric and PV devices seems one of the most interesting. Taking full advantage of this technology requires proper definition and analysis of the thermal losses occurring in PV cells. In this communication we propose a novel analysis of such losses, decoupling source-dependent and absorber-dependent losses. This analysis enables an evaluation of the actual recoverable amount of energy, depending on the absorber used in the PV cell. It shows that for incoming solar irradiation of 1000 W/m², and depending on the choice of material, the maximum available thermal power ranges from 380 W/m² (for single-crystal silicon) to 130 W/m² (for amorphous silicon).