A bidirectional inverter is provided for a renewable energy storage system which may simplify the circuitry and lower manufacturing cost by reducing the numbers of switches and control signals. The bidirectional inverter includes a pulse-width-modulation (PWM) signal provider for providing a PWM signal, a push-pull inverter coupled to the PWM signal provider and a direct current (DC) link, and an offset voltage provider coupled to the push-pull inverter and the electric power system. Accordingly, the bidirectional inverter converts DC power from the DC link into AC power or AC power from the electric power system into DC power.