Abstract: To address the challenges of heavy operation and maintenance electricity costs and difficulties in securing O&M funds at rural sewage treatment stations in the rainy regions of eastern Guangdong, this paper proposes a grid-connected system design featuring oversized photovoltaic capacity and coordinated energy storage. The system operates under the principle of self-consumption of on-site generation and storage of surplus power, and adopts a power supply strategy based on photovoltaic priority, energy storage coordination, and grid power backup. Taking a 10 m³/d rural sewage treatment station in Puning, Guangdong as a case study, this paper completes load statistics, equipment selection, and sizing calculations for photovoltaic modules, energy storage, and inverters, and carries out nine-month cross-season operation monitoring.