This is derived from life time calculation with multiple factors and variables, our controller can operate over 10 years. For instance, the power switching equipment that connected to load power is designed with safety factor 3 times over industrial standards and the micro controller is designed to endure to temperature and input voltage surge. We incorporate heat sink to reduce heat. From the experiment, the heat sink has reached only 40 degrees Celsius while the most sensitive unit can resist the heat at 105 degrees. In addition, all electronic circuits had been covered with hard resin to withstand climate condition, especially, moisture resistance problem.