Thermal Resistance and Heat Spreading Characterization Platform for Concentrated Photovoltaic Cell Receivers

Abstract

Concentrated photovoltaics (CPV) focus the sunlight on a cell area smaller than the aperture area, making the use of highly efficient multijunction solar cells cost-effective. However, the high heat flux generated under concentration can raise the cell temperature and reduce the benefits of higher concentration. Low thermal resistance cell packages (receivers) associated with effective heat sinking can alleviate this problem. This paper proposes a new experimental method and characterization platform to measure the thermal performance of a solar cell receiver in a specific cooling module. The platform injects a calibrated heat flux into a test receiver to measure its contribution to the thermal resistance, demonstrating an accuracy and reproducibility of ±0.15°C/W. A metric to evaluate the heat spreading capability of the receiver is defined and extracted from experimental measurements conducted with different thermal boundary conditions. Multiple receiver configurations and materials were characterized, demonstrating that the proposed test methodology and platform can capture their impact on the heat spreading capabilities. The results also highlight the importance of thermal interfaces and the benefits of spreading the heat in metallic layers before conducting it through the dielectric layers that form the receiver. The proposed metrics and characterization platform will therefore be beneficial for the design, experimental development, and selection of CPV receivers and cooling modules.