Photosensor control systems have been available for more than two decades, but they have struggled to gain widespread use due to issues with reliability. To address these issues, CLTC partnered with WattStopper, Walmart, Sacramento Municipal Utility District, Southern California Edison, and San Diego Gas & Electric Company to develop a more reliable, more effective daylighting control system capable of sensing changes in daylight levels with increased accuracy and responding with more appropriate adjustments in electric light levels.