A voltage divider strategy for reducing the hot spot temperature in partially shaded solar panels

Abstract

Over-temperature occurring in silicon solar panels, subject to partial shadowing, are reduced by means of a series connected voltage divider which sustains part of the reverse voltage developing across the shaded solar cells. The circuit is based on a power MOSFET which is driven by the output voltage of the solar panel. When the solar panel is uniformly illuminated the MOSFET is in the ON state and does not affect the operation of the module, while, when the solar panel is partially shaded, and the output voltage decreases, the MOSFET enters in the pinch-off operation mode, thus subtracting its voltage from the reverse voltage across the shaded cell. Experiments performed on a commercial solar panel showed one third of reduction of the reverse voltage across shaded solar cells, with a reduction of the hot spot temperature of about 25°C.