The efficiency of photovoltaic (PV) panels is significantly affected by environmental factors such as solar irradiance, wind speed, humidity, dust accumulation, shading, and surface temperature, with thermal buildup being the primary cause of efficiency degradation. In this review, we examined various cooling techniques to mitigate heat accumulation and enhance PV panel performance. A comprehensive analysis of active, passive, and hybrid cooling strategies is presented, including heat pipe-based cooling, heat sinks, holographic films, nanofluids, phase change materials (PCM), thermoelectric, biomaterial-based, and hybrid cooling systems. The effectiveness of these techniques in reducing surface temperature and improving electrical efficiency was assessed. Notably, heat pipe cooling and hybrid PCM-thermoelectric systems demonstrated the most promising improvements, with some methods achieving temperature reductions exceeding 40 ℃ and efficiency enhancements over 15%. Future research directions include developing advanced nanofluid formulations, optimizing the design of heat pipes and heat sinks, integrating multi-functional coatings, and enhancing the real-world durability of cooling materials for inventing innovative, sustainable, and eco-friendly cooling systems. By providing a structured assessment of emerging PV cooling techniques, this study is a valuable resource for researchers and engineers striving to improve solar energy efficiency, reduce thermal losses, and advance the sustainability of photovoltaic technologies.

The increasing demand due to development and advancement in every field of life has caused the depletion of fossil fuels. This depleting fossil fuel reserve throughout the world has enforced to get energy from alternative/renewable sources. One of the economical ways to get energy is through the utilization of solar ponds. In this study, a mathematical model of a salt gradient solar pond under the Islamabad climatic conditions has been analyzed for the first time. The model uses a one-dimensional finite difference explicit method for optimization of different zone thicknesses. The model depicts that NCZ (Non-Convective Zone) thickness has a significant effect on LCZ (Lower Convective Zone) temperature and should be kept less than 1.7 m for the optimal temperature. It is also observed that for long-term operation of a solar pond, heat should be extracted by keeping the mass flow rate of 17.3 kg/m²/day. The model also suggests that when the bottom reflectivity is about 0.3, then only 24% of the radiation is absorbed in the pond.