Photovoltaic plant reduced soil salinity under the panels by 56% in coastal saline lands

• PV cuts soil salt 56%–no freshwater—under panels compared with adjacent salt land. • Shade-cooled PV turns coastal salt flats into low-salt crop/pasture land year-round. • Alley soil desalts April to August, resalts in winter-seasonal switch for salt crops. • 100 MW PV matches multi-million-dollar drainage projects’ desalination effects, supplying clean energy at no extra cost. Building solar power stations on saline-alkali land promotes clean energy and efficient land use. However, concerns exist about the potential impact of photovoltaic power stations on soil salinity in such areas. Elevated salinity may accelerate land degradation and affect surrounding farmland and groundwater systems. We selected the Dongji Photovoltaic Power Station located on coastal saline-alkali land in the Yellow River Delta as a case study. Through stratified soil sampling combined with meteorological observations and water-salt transport modeling, we analyzed the seasonal dynamics and drivers of soil salinity under the photovoltaic panels, in the gaps between them, and on natural land outside the station. The results indicate the following: (1) Photovoltaic arrays reduce under-panel salinity by 56% compared with natural land, maintaining a low soil salinity level throughout the year. (2) Soil salinity between solar panels varies seasonally: it is lower than that of natural land (April to August), slightly higher otherwise. (3) Shading reduces soil temperature and evapotranspiration, stabilizing under-panel soil salinity, while fluctuations in these parameters in inter-panel gaps drive its seasonal changes. This study confirms that photovoltaic panel coverage significantly alters soil salinity patterns, offering a scientific basis and optimized management strategies for integrated photovoltaic agriculture development on saline-alkali land.