A self-powered, self-controlled device is ideal for architectural glass and other uses.

Electrochromic devices change color and light transmissivity upon application of an electric charge. As such they should prove valuable as "smart" windows that can reduce air-conditioning costs by being darkened to absorb sunlight and reject unwanted solar heat. The biggest drawback is the cost of providing a power source and controls for the windows. NREL researchers have worked on various ways of self-powering electrochromic windows with solar cells or photovoltaic (PV) films (also available for licensing). A recent development is a new form of self-controlled and self-powered photoelectrochromic system that integrates the photovoltaic and electrochromic elements into a single device.