PEG-based solid-solid phase change materials for passive cooling of solar photovoltaic panels

The solar photovoltaic (PV) conversion efficiency decreases as the solar cell temperature rises, at a reduction rate of approximately 0.5 %/°C. Phase change materials (PCMs) have emerged as a promising solution for passive thermal management of solar PV panels, providing effective and uniform cooling to enhance PV conversion efficiency. In current research on PV-PCM systems, organic solid-liquid PCMs (SLPCMs), particularly paraffin, are the primary focus. However, their application is limited by issues such as liquid leakage and large volume changes. To address these issues, solid-solid PCMs (SSPCMs) are successfully fabricated and pioneeringly introduced for effective cooling of solar PV panels in this paper. SSPCMs utilizing polyethylene glycol (PEG) with varying molecular weights are prepared through a simple and reliable two-step method, demonstrating outstanding self-healing properties. The test results indicate that the prepared PEG-based SSPCMs exhibit excellent leak-proof characteristics, with no leakage observed at 80 °C within 2 h. Their phase transition temperature ranges from 55 °C to 67 °C, with latent heat between 137 J/g and 151 J/g, and a thermal conductivity of approximately 0.34 W/(m·K) at 25 °C. The experimental results of cooling PV panels reveal that, compared to bare PV, PV panel using only SSPCM can achieve a temperature decrease of up to 11.2 °C. Moreover, PV panel with aluminum fin-enhanced SSPCM can achieve a greater decrease in temperature of 16.5 °C. The electrical performance test results demonstrate that finned PV-SSPCM effectively enhances power output. These findings suggest that aluminum fin-enhanced SSPCM presents a competitive option for PV cooling.