Specifications for maximum power point tracking in vehicle-integrated photovoltaics based on high-resolution transient irradiance measurements

Vehicle integrated photovoltaic (VIPV) systems have much different requirements on maximum power tracking compared to stationary setups. The occurrence of fast changes between full irradiance and shading are demanding. To evaluate the specific impact of these conditions on the specifications VIPV systems, we conducted high resolution measurements of the irradiance during driving in an urban environment. We found that the maximum measured irradiance on the car roof is comparable with stationary measurement and the irradiance on the sides of the car is about three times lower. We also found that irradiance changes occur predominantly at frequencies below 1 Hz but the amplitude can reach up to five times of the average irradiance.