A mobile multipyranometer array for the assessment of solar irradiance incident on a photovoltaic-powered vehicle

•Prediction of energy yields from car-mounted PV systems requires modeling of incident irradiance.•Novel approach measures irradiance with five pyranometers fixed to the car body.•Three-dimensional solar resources available to the PV system is modeled from this data.•Derived peak incidence angle differs from peak incidence angle predicted by the traditional model. Photovoltaic (PV) panels mounted on vehicle surfaces could directly power automobiles in the future. However, accurate predictions of energy yield from PV systems will be required to quantify vehicle mileage and additional power requirements. Therefore, to model the energy generation of car roof PV systems, it is essential to define a meaningful and scientifically accurate method for measuring solar irradiance. We measure irradiance with five pyranometers fixed to a car body using a mobile multipyranometer array (MMPA). This paper discusses a new approach that focuses on the incidence angle distribution model of sunlight to account for direct and diffuse components, and reports on our irradiance measurements on a stationary car using the proposed system. We define the incidence angle regarding the vector components of sunlight and analyze a model for sunlight angle distribution. Our data show that the peak incidence angle as predicted by MMPA is larger than the peak incidence angle predicted based on the conventional method. Consequently, we conclude that an irradiance distribution model based on MMPA can be applied to effectively design automotive static concentrator PV systems.