Highly Decorative, Lightweight Flexible Solar Cells for Automotive Applications

The strict CO₂ emission limit for passenger cars have been set by US, EU, Japan, China and other countries. In order to meet the requirement, it is essential to develop an alternative power source for the future cars. Power generation by solar panels is a promising renewable energy candidate because the most environmentally friendly vehicles such as electric vehicles and plug-in hybrid vehicles are equipped with large-capacity batteries that can be charged with electricity generated by solar panels. The requirements for the solar panels are paintable with desired color and to be lightweight. In this study, we developed a simple lift-off process for producing colorful and lightweight Cu(In,Ga)Se₂ (CIGS) solar cells for future automotive application. Our measurements show that the developed lift-off process can provide the lightweight solar panel that have nearly identical performance compared to that of the cell before the lift-off process. The colors were generated on the cells by coating the highly transparent automotive paint. We demonstrate a bright, uniform, and solid appearance on the solar cells with small output power reduction of less than 5% compared to the cells without the paintings for chromatic colors. We believe that the highly decorative and lightweight solar cells produced by the developed process can considerably increase the installable area of solar panel on passenger cars.