An assessment is made of energy storage for agricultural and industrial process heat applications and for space heating and cooling and water heating for residential and commercial buildings. The purpose is to identify these storage technologies that have the greatest potential to enhance the commercialization of the most promising solar thermal technologies. In the agricultural and industrial process heat application, the three solar thermal systems investigated are parabolic troughs, parabolic dishes, and central receivers, and the storage systems are mixed-tank, thermocline, two-tank, and phase change. For buildings, phase-change storage in active solar heating and cooling systems were studied in detail for two cities.