Japan’s new solar tech brings film-like panels to fragile rooftops

Japan is developing next-generation, film-type chalcopyrite solar cells designed to be lightweight enough for installation on rooftops with low load-bearing capacity, such as fragile slate roofs. This initiative, a collaboration between green tech startup PXP Inc. and Tokyo Gas Co., aims to launch commercial services by fiscal 2026. The chalcopyrite solar cells weigh less than 1 kg/m², comparable to perovskite solar cells, and offer similar power generation efficiency and durability. The project focuses on optimizing panel structure and construction methods to ensure performance, safety, and durability on roofs previously unsuitable for traditional heavy solar panels. The potential impact of this technology is significant, with an estimated installable capacity of approximately 169 gigawatts on such roofs by 2050—more than double Japan’s current solar capacity. This expansion could help address the slowing pace of solar adoption caused by a shortage of suitable installation sites and structural limitations of existing rooftops. The development also includes research into tandem solar cells