Hallanvahti Solar Park: 71,000 Screw Piles for Finland's Largest Solar Project

Helicasol, a subsidiary of Paalupiste, delivered the foundations for the Hallanvahti solar park as a fully integrated solution. The project comprised a 129-megawatt solar park, making it the second largest in Finland, covering an area of more than 200 hectares. The site conditions were exceptionally challenging, with extremely soft peat soil requiring a high level of expertise in foundation design, installation equipment, and site logistics. Eltel acted as the main contractor.

Helicasol’s operating model is based on designing foundations according to real site conditions and validating solutions through testing before final execution. At Hallanvahti, Helicasol was involved already in late 2024, when test piling and pull-out tests were carried out on site. The initial pile design was prepared based on available geotechnical investigations, then tested under real conditions. The pull-out test results were used to refine and optimise the final pile design, combining technical reliability with cost efficiency.

The project used tracker mounting systems, which follow the movement of the sun and impose specific requirements on foundations, particularly in terms of tensile and lateral loads. In total, approximately 71,000 screw piles were delivered and installed. Several pile sizes were used to match the highly variable soil conditions across the site. All piles were manufactured within the Helicasol and Paalupiste production chain and installed using Helicasol’s own equipment and personnel, ensuring full control under a single responsible party.

Installation was carried out in extremely demanding peatland conditions. Helicasol operates swamp-capable piling equipment and dedicated logistics solutions that enable efficient installation even in very soft and low-bearing-capacity soils. At peak performance, up to approximately 3,500 piles were installed per week, with 6 to 7 piling units operating simultaneously.

Quality assurance played a central role throughout. Load-bearing capacity data was recorded for every single pile based on installation torque, with all data automatically stored in the piling system. No soft spots or anomalies went undetected, and any deviations could be addressed immediately during installation. Corrosion protection was designed based on the intended service life of the solar park and the chemical properties of the soil. Piles were manufactured using Nordic or European steel, prioritising low-carbon production.