Abstract A single-phase three-wire grid-connected power converter (STGPC) with energy storage for positive grounding photovoltaic generation system (PGPGS) is proposed in this paper. The positive terminal of the solar cell array can be directly connected to the ground to avoid unexpected degradation of the special thin-film solar cell array. The proposed PGPGS consists of a solar cell array, two DC–DC power converters, a battery set, a switch set and a three-port power converter. The three-port power converter comprises a high-voltage DC port, a low-voltage DC port and an AC port. The solar cell array is connected to the high-voltage DC port through two DC–DC power converters whose positive terminal is directly connected to the ground. The battery set is connected to the low-voltage DC port, and the AC port is connected to the utility. No transformer is required in this PGPGS even when using the low-voltage battery set. A prototype is developed and tested to verify the performance of the PGPGS. The experimental results show that the proposed power converter has the expected performance.