Effect of Maintaining a Fixed Ambient Temperature on the Evaluation of Photovoltaic Device Performance

In this article, we analyze the photovoltaic effect while assuming a fixed ambient temperature and a varying system temperature rather than using the standard fixed system temperature-based approaches. We do so by complementing the photon rate balance equation (detailed balance, circuit model) with the power balance equation of the system. As a result, a simple approach capable of treating any photovoltaic system emerges. Accordingly, we study the potential-dependent current and temperature of solar cells and thermoradiative power generators. We show that the optimal band gap of a solar cell depends on its heat-transfer coefficient and that its efficiency may rise or fall as solar concentration increases, depending on its ability to dissipate heat. We also identify where the cell's efficiency and temperature turn from a conductive and/or convective-dominated cooling regime to a radiative-dominated one. For the thermoradiative case, we show that its power decreases when heat intake is suppressed and study the degrading effect of nonradiative recombination on this power production scheme. The proposed model converges to the known fixed system temperature-based approaches when an infinite ability to transfer heat is considered.