Current site planning of medium to large solar power systems accelerates the loss of the remaining semi-natural and agricultural habitats.

The global transition to renewable energy sources has accelerated to mitigate the effects of global climate change. Sudden increases in solar power facilities have caused the physical destruction of wildlife habitats, thereby resulting in the decline of biodiversity and ecosystem functions. However, previous assessments have been based on the environmental impact of large solar photovoltaics (PVs). The impact of medium-sized PV facilities (0.5-10 MW), which can alter small habitat patches through the accumulation of installations has not been assessed. Here, we quantified the amount of habitat loss directly related to the construction of PV facilities with different size classes and estimated their siting attributes using construction patterns in Japan and South Korea. We identified that a comparable amount of natural and semi-natural habitats were lost due to the recent installation of medium solar facilities (approximately 66.36 and 85.73% of the overall loss in Japan and South Korea, respectively). Compared to large solar PVs, medium PV installations resulted in a higher area loss of semi-natural habitats, including secondary/planted forests, secondary/artificial grasslands, and agricultural lands. The siting attributes of medium and large solar PV facilities indicated a preference for cost-based site selection rather than prioritizing habitat protection for biodiversity conservation. Moreover, even conservation areas were developed when economic and topological conditions were suitable for energy production. Our simulations indicate that increasing the construction of PVs in urban areas could help reduce the loss of natural and semi-natural habitats. To improve the renewable energy share while mitigating the impacts on biodiversity, our results stress the need for a proactive assessment to enforce sustainable site-selection criteria for solar PVs in renewable energy initiatives. The revised criteria should consider the cumulative impacts of varied size classes of solar power facilities, including medium PVs, and the diverse aspects of the ecological value of natural habitats.