摘要： Nano-porous thermal cooling layer (TCL) of thickness 14 mm beneath a Si solar cell reduces its working temperature from 82 °C to 68 °C This reduced working temperature increase its absolute working ef?ciency by 0.75%. X-Ray diffraction analysis of the material used in TCL shows its amorphous nature. The SEM images con?rm interconnected carbon particles are forming micro-channels within the TCL. Further FESEM analysis has been done to examine the in-depth structure of the carbon particles and shows the nano-porous topography within the particle. The porosity of used TCL is examined by BET measurement which con?rms the highly porous nature of the TCL having surface area of the order of 798.35 m2 g?1 with average pore size of 2.3 nm. The induced water concentration (0.049 to 0.49 ml cm?3) dependent enhanced cooling ef?ciency of nano-porous TCL has been studied in detail. The use of water saturated (0.49 ml cm?3) TCL (14 mm thick) further decreases the working temperature of the device from 68 °C to 58 °C and the device works below this temperature for around three hours. Further, in order to enhance the effective time duration, the TCL thickness (4 mm to 26 mm) dependent cooling ef?ciency of water saturated TCL has been analyzed in detail. Use of optimized water saturated TCL beneath the solar cell improve its working ef?ciency from 11.4% (at 82 °C) to 12.69% (at 58 °C) which shows an absolute and relative enhancement of 1.29% and 11.32%, respectively in cell ef?ciency. Finally, thermal analyses of TCL and water cooling mechanism in it have been discussed in detail.