Heat generation and mitigation in silicon solar cells and modules

Abstract

Cost-effective photovoltaics (PVs) require a high energy yield with a long system lifetime. However, both are adversely affected by temperature. Here, we assess the economic impact of thermal effects on PV systems by establishing a temperature-dependent levelized cost of energy (LCOE) model. Using this model, we introduce an equivalent ratio γ (with the unit of absolute efficiency %/K) as a new metric that quantitatively translates the LCOE gain obtained by reducing the module temperature (Tmod) to an equivalent absolute power conversion efficiency increase. The substantial value of γ motivates us to investigate the root causes of heating in solar cells and modules, with a focus on crystalline-Si (c-Si) PVs, given its market dominance. To link the heat analysis with Tmod, we establish and validate an opto-electronically coupled thermal model to predict Tmod. This modeling approach enables the quantification of possible ways to mitigate undesired heating effects. Aside from conversion of sunlight to electricity, all solar cells generate and dissipate heat, thereby increasing the module temperature above the environment temperature. This can increase module and system costs by lowering its electrical output and shortening the module lifetime. We assess the economic impact of thermal effects on PV systems by establishing a temperature-dependent levelized cost of energy (LCOE) model. Using this model, we introduce an equivalent ratio, γ (with the unit of absolute efficiency %/K), as a new metric that quantitatively translates the LCOE gain obtained by reducing the module temperature to an equivalent absolute power conversion efficiency (PCE) increase. γ, most importantly, demonstrates that once the PCE approaches a practical upper limit, work on the control and mitigation of the module temperature can be equally or even more significant than costly marginal gains in PCE. The economic impact of thermal effects on PV systems is assessed by establishing a temperature-dependent levelized cost of energy (LCOE) model. We introduce an equivalent ratio, γ, as a new metric that quantitatively translates the LCOE gain obtained by reducing the module temperature to an equivalent absolute power conversion efficiency (PCE) increase. γ demonstrates that once the PCE approaches a practical upper limit, work on mitigating the module temperature can be equally or even more significant than costly marginal gains in PCE.