In the week to 30 September 2026, the Baltic and Nordic battery market showed two faces at once: developers pushed record volumes into construction across Poland, Lithuania and Estonia, while fresh data showed Baltic revenues per MW slipping again and Nordic grid operators rewriting the rules on frequency reserves. The through-line is a market growing up, where installed volume is rising but the easy per-MW money is on the move. Every figure below links to its source.
Poland’s biggest battery breaks ground as the Baltic and CEE build-out speeds up
Greenvolt Power started construction on the 600 MW/2.4 GWh Siedlce project, set to be Poland’s largest battery when it comes online at the end of 2027, supplied by BYD and built by P&Q and ONDE (Energy-Storage.news, 24 September). With the 200 MW/800 MWh Turośń Kościelna site already running and an identical Nowa Wieś Ełcka plant due in the fourth quarter, the three projects total 1 GW/4 GWh, all backed by capacity-market contracts that the developer calls the bedrock of the business case for large-scale storage in Poland. The activity spread across the region in the same roundup: Gore Street’s EU fund bought the 40 MW/160 MWh Wolborz project (capacity payments from 2030), DS1 and BLEnergy began building a 140 MW/327 MWh battery at a new 330 kV substation in Alytus, Lithuania, and Finland’s Taaleri Energia invested in a 192 MW/420 MWh system in Estonia developed by Evecon and Corsica Sole, with construction starting now and operation targeted for November 2027.
Two details matter more than the megawatts. Energy-Storage.news notes the Baltic market is still driven by high ancillary-service prices, but durations are pushing past one and two hours as owners shift toward energy trading and other uses. And in a separate interview, European Energy’s regional director for Central Europe argued that predictable market rules now count for more than subsidies, that banks’ main concern has become revenue, and that optimisation across several markets is where competitiveness will be decided (Energy-Storage.news, 29 September). Underneath it, the plumbing is deepening too: a second power exchange, EPEX SPOT, is completing its Baltic roll-out, with day-ahead auctions going live at the end of September alongside Nord Pool (The Baltic Times).
What this means if you are building or buying in the Baltics, Poland or the Nordics. The build-out is real, but the roundup and the interviews point the same way. Volume alone will not pay. Three things worth doing now.
First, lock your route to market before commercial operation, not after. A contracted floor or availability payment can carry the core economics while you keep the upside, and it is what banks want to see.
Second, design for longer durations and energy trading, not ancillary-only. The Baltic ancillary premium that carried the first movers is thinning, and the assets going into the ground now are being built to trade.
Third, treat siting and optimisation as one decision. A battery at a constrained node is not the same asset as one elsewhere, and value increasingly comes from moving capacity between markets, now across two Baltic exchanges.
This is our day job. Fusebox integrates and dispatches BESS, PV, EV chargers, HVAC systems and C&I industrial loads on a single platform, and we operate across 15 European markets and 9 TSOs. If you are building in the region, let us map how your assets earn across all of them.
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Battery revenues rose across most of Europe in August, but the Baltics fell again
Clean Horizon’s August index, reported by Energy-Storage.news, showed a widening split (ESS News, 24 September). Spain rose 1% to 6%, with a two-hour battery reaching a range of €482,000 to €506,000/MW/year; France gained 6.1% to €294,000; Italy edged up 2.2% to €331,000 on a day-ahead spread of €131/MWh; and Portugal climbed 16%. The Baltics went the other way, and did so for a second month running after July’s declines (ESS News, July index): Estonia fell 13% to €152,000/MW/year, while Latvia and Lithuania each dropped 17%, to €307,000 and €251,000, as ancillary prices softened. Germany slipped between 1% and 6%, and Romania fell around 35% as new capacity such as the Gura Ialomiței battery came online. In Clean Horizon’s framing, the takeaway is the growing importance of market mix.
A second August read made the point sharply. Optimiser Suena reported that in Germany, cross-market optimisation earned about €25,300/MW for the month, roughly 65% above the strongest single-market strategy, even as most static single-market strategies earned less than in July and day-ahead negative-price windows shrank from 79 hours to 55 (ESS News, 25 September). Higher average power prices did not lift static returns; the spread and the switching did.
For the BESS owners and portfolio managers reading the monthly index and worrying. The real story is not that one market went up and another went down. It is that the gap between a battery sat in one market and a battery moved between markets is now the biggest number on the page. Same hardware, same week, very different revenue. If your assets sit in the Baltics, the ancillary cushion is thinner than it was, so the case for trading across day-ahead, intraday and reserves at once is stronger, not weaker. That switching is what we do every day. For the exploratory questions, our Fusie knowledge bot can help you scope where revenue is leaking, and then let us get specific.
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Nordic grid operators capped static frequency reserves, tilting the market to fast assets
On 29 September, with the first delivery day on 30 September, the Nordic transmission operators Energinet, Fingrid, Statnett and Svenska kraftnät switched on a volume limit for static FCR-D upward regulation (Fingrid). The fixed cap starts at 50% of total Nordic demand for FCR-D up, with an inertia-dependent variable component to follow; in Fingrid’s area the go-live limit is 308 MW of static FCR-D, and it expects the near-term impact in Finland to be limited. The point of the cap is to guarantee a minimum share of dynamic FCR-D, the faster and repeatable variant, under Article 153 of the System Operation Guideline (Svenska kraftnät).
The distinction is the whole point. Static providers get a 15-minute grace period and slower requirements; dynamic providers, the category batteries deliver, do not, and are now protected from being crowded out (Statnett). Accepted static bids are still cleared at the same marginal price as dynamic ones up to the cap, and the operators plan to refine the method by March 2028.
If you run, or are prequalifying, batteries in the Nordics. The direction is set. Reserve markets are being redesigned around fast, dynamic response, and the slower static providers are the ones being capped. For batteries that is a tailwind, but only if you are qualified for the dynamic products and can move capacity into them when they pay. The limits will tighten again when the variable, inertia-linked component arrives, so being on the right side of the static and dynamic line is worth more over time, not less. We help owners prequalify and dispatch across reserve and wholesale markets so capacity lands where it earns.
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Regulatory and market watch
- Portugal postponed its 1,050 MVA storage auction, which had been set for 14 September; its National Energy Storage Strategy, now in public consultation, targets 6.9 GW of storage by 2030 (pv magazine, 23 September).
- Germany’s first StromVKG capacity auction names winners on 3 November, with the second long-term auction’s bid deadline announced on 10 November; batteries are shut out of the first rounds by the ten-hour rule and can first bid in the May 2027 generation auction (Energy-Storage.news).
- Energy Storage Europe published a report calling for an overhaul of the EU cybersecurity framework for batteries, spanning the Cyber Resilience Act, NIS2, the Network Code on Cybersecurity and the proposed Cybersecurity Act 2.0, warning that divergent national rules are raising costs and slowing deployment (Energy-Storage.news, 28 September).
- Spain’s capacity-market order is live, but the first auctions still have to be scheduled and designed (ESS News).
- Under the EU market-design reform, member states are due to set indicative non-fossil flexibility targets by the end of 2026, following national flexibility needs assessments (ACER).
- The Baltic TSOs Litgrid, Elering and AST are due to submit their third-quarter annual balancing review, including the planned phase-out of the demand-reduction reserves that have propped up the market (Elering).
