Direct liquid-immersion cooling of concentrator silicon solar cells in a linear concentrating photovoltaic receiver

Direct liquid-immersion cooling of solar cells using dimethyl silicon oil is proposed as a heat dissipation solution for linear CPV (concentrating photovoltaic) systems. To reduce the liquid holdup, a narrow rectangular channel receiver was designed and its heat transfer performance was investigated experimentally at an energy flux ratio of 9.1 suns. Long-term stability of mono-crystalline concentrator silicon solar cells immersed in dimethyl silicon oil with viscosity of 2 mm2/s was monitored under real climate conditions. Experimental results show that the liquid-immersion cooling capacity in the designed receiver is favorable. The cell temperature can be controlled in the range of 20-31 °C at a 910 W/m2 DNI (direct normal irradiance), 15 °C silicon oil inlet temperature and Re numbers (Reynolds) variation from 13,602 to 2720. The cell temperature distribution is quite uniform, and a general correlation of Nu number (Nusselt) was obtained. The electrical performance of the cells immersed in the silicon oil is stable and no obvious efficiency degradation was observed after immersed for 270 days.