Abstract: A power conversion device includes a DC-DC converter, a DC-AC inverter and a relay. The DC-DC converter leads in a DC from an external solar panel and transforms the DC into a direct voltage. The DC-AC inverter transforms the direct voltage from the DC-DC converter into an alternating voltage and connecting to an external electric load via electric load output ends. The relay includes a coil connected to an external commercial power line via commercial power input ends, and conductive contacts actuated by the coil and serially-disposed between the commercial power input ends and the DC-AC inverter, and with the commercial power line electrifying the coils, the conduction control is formed therebetween, preventing the electric energy of the solar energy generation from inversely transmitting to the commercial power line when interrupting the commercial power service.