Static concentrator photovoltaics for automotive applications

This research investigated the benefits of utilizing solar power as an energy source for future passenger vehicles and an innovative static concentrator photovoltaic module for practical automotive applications. Due to strict emissions standards, alternative energy sources must be found for vehicles in the future. It was estimated that replacing all passenger vehicles with hybrid vehicles (HVs) equipped with an 800 W rated-power solar module that generates an average output of 1.8 kW h/day would reduce CO2 emissions by 63% in Japan. To confirm the validity of this estimation, a test vehicle was created by installing a 6.8 m2 solar module onto a commercially available plug-in HV. An average power generation of 2.1 kW h/day was obtained by this solar module over 100 days under real-world conditions, which was larger than the power required to achieve the estimated CO2 emissions reduction. In addition, an innovative static low-concentrator with III-V cells was studied to help reduce the installation area of the solar module on the vehicles, which is essential for practical passenger vehicles. A new concentrator design method was proposed that can be easily integrated into a standard vehicle design procedure by utilizing numerical optimization in a CAD-friendly environment. Both design equations and a design example are discussed in this paper. The proposed lens design (asymmetric-aspheric type) can expand the acceptance incident angle of solar light and increase the annual energy yield of a solar panel, while maintaining the essential thin structure for automotive applications. In spite of the wide range of sun positions, this asymmetric-aspherical lens can maintaining stable illumination on the cell while suppressing the maximum spot intensity to 20×.