A hybrid system utilizes waste heat to improve solar cell efficiency

Waste heat from photovoltaic (PV) arrays can be efficiently utilized by thermally regenerative electrochemical cycles (TRECs) to improve overall power output as a hybrid system, according to authors of a report in the Journal of Renewable and Sustainable Energy.

During solar power production, heat is often generated as a byproduct from the use of optical concentrators to direct sunlight onto PV arrays. In theory, photovoltaic-thermoelectric (PV-TE) hybrid systems can use the otherwise wasted heat to generate additional electricity, so researchers are investigating if these approaches are efficient enough to be practical.

According to their calculations, higher solar irradiation would increase the photocurrent and therefore the efficiency of the PV array, but this increase is overwhelmed by the reverse saturation current when the solar irradiation becomes too high, resulting in an overall negative influence on the PV’s performance. Their calculations show that the addition of TRECs into the system can offset the problem enough, such that the increase in solar irradiation can improve the system’s overall efficiency up to 16 percent, with 50 percent recuperation efficiency.

The paper also provides a comprehensive breakdown of their calculations including descriptions for relevant variables such as the number of PV and TREC cells, the specific heat capacity, and specific charge capacity of chosen materials. Other researchers may use these equations for optimizing PV-TREC hybrid systems in the future.

Source: “Performance optimization of a photovoltaic solar cell-based hybrid system,” by Yuan Wang, Haidong Li, Haoshan Hao, and Xiaohang Chen, Journal of Renewable and Sustainable Energy (2018). The article can be accessed at https://doi.org/10.1063/1.5028147 .