Evacuated tube SWH for commercial application consists of solar collectors in large quantity and custom sized hot water tank. A hot water circulation pump together with differential temperature controller is installed to circulate the water between hot water tank and the collectors. As the collectors are high temperature/pressure sensitive, it is very important to maintain right flow rate through the collectors at different solar intensity. It is also equally important to avoid any pressure inside the collector. This model of solar water heater is the most economic, yet reliable water heating solution for low temperature commercial applications.