Selection Map for PV Module Installation Based on Shading Tolerability and Temperature Coefficient

Abstract

Power generation from photovoltaic (PV) modules suffers from heat losses that are a function of the temperature coefficient of maximum power ( γ ) of the PV module. Another loss mechanism is shading, where the power output of the module and ultimately the system can be severely compromised. Various approaches such as passive, active, or smart bypasses and module level power electronics have been employed to minimize the effects of shading on a PV module. So far, the performance of a PV module under shading had only been addressed vaguely and was generally described qualitatively. Therefore, a probability-based parameter called shading tolerability (ST) was recently developed to quantify the behavior of PV modules under all kinds of shade. However, the observations pertaining to ST were only carried out at 25 °C ambient temperature. Hence, this paper aims to: 1) investigate whether ST is an innate property of a PV module by formulating a correlation between ST and ambient temperature, 2) classify various PV technologies based on ST and γ, and 3) develop a PV module selection map. Theoretical result shows that thermal features of a PV module (nominal operational cell temperature and γ) can influence the PV module ST by 12.25%. Also, an analytical limit is derived for ST variation with respect to ambient temperature change $(\Delta \text{ST}/ \Delta T_{a})$ . The proposed selection map, which is similar to the Ragone plot for energy-storing devices, is validated using the data of 27 PV systems installed in the Netherlands. The map can be used for optimal selection of PV modules for the design of PV systems simply by knowing the specifications of the module along with the meteorological conditions of the installation location.