Calculation method for configuring a photovoltaic pumping system for the efficient use of climatic resources

Photovoltaic (PV) pumping systems are crucial for rainwater harvesting and irrigation in mountainous rain-fed agricultural regions during the rainy season. However, in monsoon climate zones, frequent rainfall during the wet season limits sunlight availability, constraining the efficiency of PV water-lifting systems and highlighting the urgent need to optimize climate resource utilization in PV agricultural irrigation technology. To address this, in this study, Guizhou Province, a representative East Asian monsoon region, was selected as the research area; and a calculation method for the PV agricultural irrigation configuration based on climatic and agricultural regimes was developed. Analysis of 43 years (1981–2023) of climate data and agricultural systems revealed the following: 1. Regional precipitation is concentrated from April to September, accounting for 70% of the annual total precipitation, while peak sun hours from April to October account for 63% of the annual total peak sun hours (PSH). Precipitation and solar radiation exhibit a typical alternating wet‒dry pattern, leading to mismatches among rainfall, sunlight, and farming schedules. Consequently, PV agricultural irrigation requires independent storage of both solar energy and rainwater. 2. The annual wet season comprises multiple rainfall–sunshine cycles, each forming an operational period for the PV pumping system. By quantifying precipitation volumes during rainfall phases and peak sunshine hours during solar phases within each cycle over a 43-year period, these parameters serve as core inputs for the configuration calculation method, enabling efficient climate resource utilization. 3. Field tests at three sites demonstrated that the PV pumping system configured using this algorithm achieved > 90% water collection-to-storage efficiency across three consecutive rainy seasons, with no significant variations in performance under different cycles, rainfall intensities, or locations.