Iranian Sustainable Building Scientific Association International Journal of Urban Management and Energy Sustainability 2538-1628 7 2 2026 04 01 Enhancing the Energy Efficiency of Photovoltaic Panels by Using Phase Change Materials: An Experimental Study 162 178 738225 10.22034/ijumes.2026.2069892.1327 EN Mohsen Ranjbar Zeinali Department of Architecture, Imam Khomeini International University, Qazvin, Iran 0009-0006-6299-5084 Seyed Rahman Eghbali Department of Architecture, Imam Khomeini International University, Qazvin, Iran 0000-0002-4589-690X Journal Article 2025 08 25 <span lang="EN">Global energy demand and climate concerns have accelerated photovoltaic (PV) deployment, yet excessive heat accumulation under high solar irradiance remains a critical barrier to efficiency. Elevated operating temperatures reduce electrical output by approximately 0.5% per °C and accelerate long-term degradation. This study experimentally investigates the integration of Polyethylene Glycol 600 (PEG-600) as a phase change material (PCM) for passive thermal management of PV modules under dynamic electrical loading conditions. Two identical polycrystalline PV modules were tested side-by-side on a rooftop in Tehran, Iran, during peak summer irradiance (June 2024). One module (PV-Ref) operated without modification, while the other (PV-PCM) was thermally coupled to a rear-mounted aluminum container filled with PEG-600 (melting point: 17–22 °C). Both systems were subjected to variable resistive loads (1.5–150 Ω) to simulate real-world electrical demand fluctuations. Temperature, voltage, current, and irradiance were recorded at 10-minute intervals using calibrated sensors. The PV-PCM system maintained significantly lower operating temperatures, with a maximum temperature differential of 37.3 °C observed at 1200 W/m² irradiance under 1.5 Ω load. This thermal regulation translated to an average electrical power improvement of 10.8% compared to the reference module, with peak gains reaching 15.2% during high-load conditions. The PCM effectively buffered temperature spikes during transient irradiance fluctuations. PEG-600-based passive cooling offers a practical, maintenance-free approach to enhance PV performance in high-radiation climates. However, validation through long-term field deployment and techno-economic analysis is required before large-scale adoption.</span> https://www.ijumes.com/article_738225_1daeeede2e977bb704d6e3d91fbd0a2c.pdf