Croatia’s renewable build-out is sharpening the commercial case for battery storage, after the country had about 220 hours of negative electricity prices in the first half of 2026. Wind and solar account for 44% of installed capacity, while the expansion is creating greater power-market volatility and increasing the commercial relevance of batteries.
AdriaFlex is seeking partners for a 170 MW portfolio of standalone battery projects across three sites in Croatia. The developer is also working on an additional early-stage battery energy storage system pipeline of around 200 MW and is targeting ready-to-build status for its projects in the fourth quarter of 2028.
Negative prices indicate that generation is arriving faster than the power system can shift or absorb it. Separately, developer wpd plans to repower Croatia’s Trtar Krtolin wind farm, which currently has a capacity of 11.2 MW, to as much as 30 MW using fewer, larger turbines, and add a 10 MW battery. Annual output is expected to increase from around 30 GWh to about 55 GWh.
The planned repowering and battery would turn Trtar Krtolin from a generation-only asset into a hybrid project intended to focus on market value as well as output. Croatia is presented as an early Southeast European example of storage economics shifting from reliance on policy support toward merchant optimisation.
The commercial question is how quickly batteries can earn revenue from intraday spreads, charging during negative-price periods, balancing and congestion before competition compresses returns. Storage revenues are expected to depend increasingly on combining arbitrage, balancing and grid services rather than relying on a single contracted income stream.