In order to satisfy the above requirements for an ac module inverter, the authors present a novel flyback-type utility inverter based on the flyback operation theory illustrated in Fig. 7 [11]. One of the advantages of the flyback inverter lies in that an ac current injected from the utility inverter into the utility line can be determined individually, owing to individual flyback operations [12]. Moreover, the flyback inverter enables realization of the current sharing operation among the inverters connected in parallel to the utility line without use of a specific current sharing controller. Another advantage of the proposed inverter lies in provision of a novel power decoupling circuit that removes the low frequency power pulsation that appears on the dc input line, and enables use of small capacitance on both the dc input line and the decoupling circuit. Hence, film capacitors or ceramic capacitors can be used instead of electrolytic capacitors. As a result, an extension of the lifetime of the inverter under high-temperature conditions is expected, because these capacitors have lifetimes much longer than those of the electrolytic capacitors. The proposed inverter circuit also enables realization of small volume, lightweight, and low manufacturing cost.