Introducing the first ecovoltaic parks of Hungary: a reconciliation between solar development and nature conservation

Solar energy is the most rapidly growing renewable globally. However, ground-mounted solar panels have a high land requirement, leading to extensive, low-nature-value photovoltaic parks. This may be alleviated by considering ecological aspects during their planning, construction and mainetnance. The resulting ecovoltaic park can bring various benefits for the owners if ecosystem services related to the imporved ecological conditions are recognized and wisely utilized. A major step in developing ecovoltaic parks is the creation of a short but species-rich grassland ecosystem. There is little empirical evidence on how to achieve this; therefore, we set up an experimental sowing experiment in three formerly conventional photovoltaic parks located in the forest-steppe zone of Hungary. From the regional native grassland species pool, we selected short but competitive ones (two graminoids and 50 forbs that are often visited by pollinators), and sowed them in half of the parks (between panel rows) in October, 2022, while the other half was left as control. In 2023, we surveyed the vegetation of the sown and control parts of the parks and adjacent old-growth grasslands (as references), and found that total plant species richness and the species richness of grassland specialists increased compared to the control sites, but remained below the references. In contrast, the cumulative cover of grassland specialist species in the sown sites could reach the references. We also surveyed pollinator assemblages (hoverflies and wild bees), and found higher species richness and Shannon diversity in the sown parts then in the reference grasslands, while control parts of the parks showed intermediate values. This might have been caused by spillover from the sown parts, although flying pollinators might have also taken advantage of the permanent windshade among the panel rows of control parts, despite the low food supply compared to the reference grasslands. Our findings suggest a rapid improvement of plant and pollinator assemblages after sowing native seed mixtures in solar parks. The resulting high-nature-value grassland ecosystem can have many co-benefits for the owners, as (i) it requires lower management intensity due to the short vegetation, (ii) has the potential to offer high-quality forage for livestock or honey-bees, and (iii) lowers the widespread “not-in-my-backyard” syndrome of local inhabitants due to its attractive, flower-rich appearance.