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Enhancing Biodiversity in Solar Power Projects – Case Tarvasjoki
9 July 2025 at 11:45 EEST
In 2023, Fortum introduced a comprehensive set of biodiversity-supporting goals to ensure that the energy transition does not come at the expense of nature. As part of commitment to these goals, Fortum has conducted several case studies to understand how new power plants can be built without overall degradation of biodiversity. One of these case studies is located at a 50-megawatt solar power project site in Tarvasjoki, Southwest Finland.
The primary objective of the Tarvasjoki case study was to test various measures that could enhance the ecological value of the project area. The study, conducted using two different measurement tools, revealed that the solar power project could achieve a significantly positive impact with feasible measures implemented in the project area.
The greatest impact was observed in measures covering a wide area, such as planting vegetation under and between the solar panels. This measure was found to be extremely beneficial for ecological value. Planting vegetation not only stabilizes the soil during construction but also helps manage stormwater. Additionally, landscaping, typically done to reduce the visual impact of solar panels, can also significantly enhance the ecological value of the area if carried out in a biodiversity-promoting manner. The measurement tools indicated that if no improvement measures were taken in the project area, the ecological value would decrease by approximately nine percent due to the solar project. According to the case study, the positive impact on natural values can be 9-25 percent, depending on the success of improvement measures such as planting in the project area.
The Tarvasjoki solar power project covers a total area of approximately 76 hectares, most of which is agricultural land leased for panel placement. Additionally, about nine hectares of the project area is forest, where support structures, a substation, a grid connection, and possibly an electricity storage system are planned.
"Our recent case study shows that in this type of project area, we can even significantly increase the ecological value of the area. Such research data has not previously been available in Finland related to solar power projects," says Johanna Korpela, a sustainability expert specializing in Fortum's wind and solar power business.
The Tarvasjoki, more specifically the Murronväljä solar power project, is in the zoning phase, and the zoning draft is currently being prepared. The development phase of a solar power project, including environmental studies and permitting, typically takes about 1-2 years. After obtaining the building permit, Fortum will make a possible investment decision for the project.