A heat transfer model for concentrating silicon solar cells in a spectrally splitting hybrid receiver

Photovoltaic solar cells under concentrated illumination require passive or active cooling. This paper aims at analyzing the heat transfer in concentrating back contact silicon solar cells for a hybrid photovoltaic/thermal receiver, using a combined electro-thermal numerical model. The concentration ratio on the cells has been assumed to be up to 100 suns (for linear concentrator applications). It is shown that the presence of voids in the solder joints has a significant effect on the performance of the heat transfer circuit especially if the solder layer doesn't cover the whole face of the cell contacts (i.e. using point solders). The cell-to-heat-sink temperature difference can reach above 50°C because of the internal thermal resistance of the cell mounting structure (excluding the convective heat transfer resistance of the heat sink). Reducing the void content and increasing the solder area have significant effect on reducing this temperature difference. A heat sink convection heat transfer coefficient has been added to the model to simulate a typical water cooling channel. It is shown that spectral beam splitting can be employed to keep the cell temperature below 60°C for concentration ratios of up to 100 suns.