Utility-interactive photovoltaic power generations have been accepted and spread widely. Various innovative power conditioning systems have been also studied. In domestic utilization, the actual application of such solar panels is almost installed on top of the roof of the detached house. However, some residents living in the apartment house are having fairly strong desire to contribute for energy saving due to natural energy generation. The generating power in such case is fairly reduced, so the system construction should balance the reduced power. Thus, it is necessary to improve the construction toward simple one. In this paper, in order to give a reply, simple and concise power conditioners, especially inverter systems are devised and examined. Considering fairly reduced generation power and narrow space of installation, the system constructions should be compact. The circuit which gratifies their wishes are presented and discussed.