Nurmijärvi (Helen and Evli)
Operating, 40 MW · 80 MWh, in Nurmijärvi, owned by Helen Ltd and Evli Renewable Energy Infrastructure Fund II. Every fact below is as a published source states it, with the address beside it; a field not shown is one no source gave, and nothing is guessed.
The battery
| Power | 40 MW |
| Capacity | 80 MWh |
| Duration | 2.0 hours |
| Status | Operating, as of 2 December 2025 |
| Owner’s date | December 2025, actual |
| Municipality | Nurmijärvi |
| Grid connection | National grid near Fingrid transmission network |
| Placed on the map | at the centre of Nurmijärvi, its municipality (GeoNames) |
Who is behind it
| Owner | Helen Ltd and Evli Renewable Energy Infrastructure Fund II |
| Developer | Evli (with Siemens) |
| Built by | Siemens (technology supplier: electrification, energy management software, lifecycle services); 36 container modules, maker not named |
A joint venture. Helen Oy is 2630573-4. YTJ lists Nurmijärven Sähkövarasto Oy (3333212-4) by name only; no source ties it to this battery.
Not published anywhere we have found: ultimate owner, cells. The page says so rather than guessing.
What the sources say
Helen says "over 40 MW" and "exceeding 80 MWh"; the figures here are those floors.
Evidence and sources
- name: https://www.helen.fi/en/news/2025/one-of-finlands-largest-electricity-storage-systems-comm…
- developer: https://www.helen.fi/en/news/2025/one-of-finlands-largest-electricity-storage-systems-comm…
- builder: https://press.siemens.com/fi/en/node/240 https://www.helen.fi/en/news/2024/Helen-to-improv…
From the owners’, developers’ and builders’ own releases, council decisions and permit bulletins, read by Vitreous and checked against the owners’ own words on 12 October 2026; a bracket such as “(Energy-Storage.news only)” in a field means the trade press is still the only source for it. Fingrid publishes no meter, no price and no instruction per battery, so this page carries no money: what one megawatt is paid in Fingrid’s markets is on the markets page, for the whole market and never for a named battery. List id FI-B015.