As the world accelerates toward electrification, integrating solar photovoltaics (PV) into vehicles is emerging as a promising way to enhance energy efficiency and reduce carbon emissions. A new report by the International Energy Agency Photovoltaic Power Systems Programme (IEA PVPS) highlights 2 critical aspects of vehicle-integrated photovoltaics (VIPV): irradiance and temperature uniformity on curved vehicle roofs.PV-Powered EVsWith battery and plug-in hybrid electric vehicles (EVs) becoming mainstream, charging from sustainable sources is essential to maximize emissions reductions. While grid-connected and standalone PV charging stations are growing in popularity, on-board PV systems provide an opportunity for direct, independent power generation. VIPV systems incorporate PV modules into vehicle surfaces, working alongside energy management systems and storage elements to maximize solar power utilization.However, PV performance on a curved vehicle surface differs significantly from traditional flat-panel installations. The IEA PVPS Task 17 research team investigated how irradiance mismatches and temperature variations affect power generation and identified challenges for optimizing energy efficiency in solar PV-powered vehicles.The study measured irradiance and temperature on a 1.4 x 0.9 m vehicle roof using a 5 x 5 sensor matrix over an 8-day period in August 2023 in Le Bourget du Lac, France.Key FindingsThe study revealed that:On clear sunny days, irradiance differences of up to 250 W/m² (21%) were observed between the best- and worst-oriented solar cells. Temperature variations of up to 13°C across the vehicle roof were recorded under the same conditions.On rainy days, irradiance differences were less than 20 W/m², and temperature differences remained under 3°C.These insights highlight the need to account for curvature-induced irradiance and temperature mismatches when designing and optimizing VIPV systems for real-world performance. The report emphasizes the importance of considering solar exposure variability in vehicle design and developing adaptive energy management strategies. It also recommends further testing and modeling to refine energy prediction systems, ensuring maximum efficiency for PV-powered vehicles.Recently, DartSolar LLC launched its VIPV solution for EVs - an extendable solar roof rack that can extend the range by 5 to 10 miles (see Extending EV Range With Solar Roof Rack).
