Solar Sensor (IMAGE) Naval Research Laboratory Caption Solar sensor boxes attached to the top of mobile solar power unit packs directly measure the amount of solar irradiation (sunlight) visible to the photovoltaic panels. Credit (US Naval Research Laboratory) Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.