Effects of solar cell heating due to nonuniform surface irradiance on the photovoltaic conversion efficiency of a HCPV module

Here we investigate how inevitable heating of a solar cell, resulting from its nonuniformly distributed surface irradiance, affects the overall photovoltaic conversion efficiency of a high-concentration photovoltaic (HCPV) module utilizing the solar cell. To that end, a thin infinite plate is considered to model the PV backsheet. At the center of the backsheet, a circular spot modeling the solar cell is subjected to an axisymmetrically distributed surface irradiance. Assuming also a linear temperature dependence of the local photovoltaic conversion efficiency of the solar cell, i.e., a constant "temperature coefficient" of the conversion efficiency, we calculate the steady-state temperature distribution on the cell-and-backsheet module analytically. The overall (or, spatially averaged) photovoltaic conversion efficiency of the cell then is evaluated. Through a systematic and realistic parameter study for a two-zone cell-surface irradiance dustribution, it is demonstrated that cell-surface irradiance non-uniformity tends to decrease the overall module conversion efficiency. But with sufficient cooling and a small temperature coefficient of the cell conversion efficiency, the module conversion efficiency can be brought closer to the ideal value. The analytic methodology and results presented here are expected to be useful for HCPV system engineers to optimize their module design.