Recently, various hybrid systems are proposed as primary power supplies for communications. First, hybrid conceptions are put in order. Then experiment results of the triple hybrid primary power supply system combining a wind turbine, a solar battery and a diesel generator are stated. Next, a design method for required battery capacity in various systems is given. Applying this method, the complementary grade of wind and sunshine is quantitatively observed, and it is shown that the triple hybrid system is most economical.