Critical analysis of optimized energy harvesting at small-scale by thermally coupled photovoltaic-thermoelectric systems

The prospect of combining, at small-scale, a photovoltaic cell and a thermoelectric generator has emerged as a promising approach to enhance the non-recovered and unexploited heat from a photovoltaic cell. The increase of efficiency compared to standalone photovoltaic systems has varied, in some cases, up to 30% compared to the measured base efficiency. With the potential of improving the electrical energy generation capabilities of solar photovoltaic cells, it is no surprise innovative research regarding these hybrid photovoltaic-thermoelectric (PV-TE) systems has substantially increased over the last few years. In this analysis, electrical aspects of thermally coupled photovoltaic-thermoelectric energy harvesting systems observed in research are discussed and their main properties and specificities are reviewed and analyzed. A particular focus is made on the possible electrical connection between the photovoltaic cell and the thermoelectric generator within the hybrid system. The control mechanism for maximum power point tracking (MPPT) to achieve optimized power extraction, based on studies, is also addressed. Additionally, limitations and possible improvements are discussed regarding power extraction due to their specific needs for an electronic interface.