One particular study set the tone at this year's SolarFlex Croatia conference in Zagreb, and its conclusions caught even seasoned market participants off guard. The work covered 13 countries and ran more than 8,000 generators through over 30,000 parameters across eight scenarios, building a picture detailed enough to test how storage might actually behave under real grid conditions. The underlying data came from ENTSO-E, the European network of transmission system operators, supplemented by regional power exchanges, national energy and climate plans, and the development pipelines published by the transmission operators themselves.
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The scale of the exercise was necessary because Croatia, a small country of unusual geographic shape, can only be assessed in conjunction with its neighbours. The long, narrow strip of Adriatic coastline and the inland territory reaching north and far to the east shape how a complete energy system has to be operated.
Congestion management as a business model for storage
The findings shift the economic logic of the Croatian storage market. "These necessary storage projects can be viable, profitable and economically justified solely by providing a service that removes grid bottlenecks," says Igor Kuzle, head of the Smart Grid Lab at the University of Zagreb. "That is a very optimistic and promising prospect for everyone involved, from grid operators to storage investors and political and administrative decision-makers."
Croatia – study outlines need for large-scale battery deployment
The planned upgrade of the ageing grid, intended to better integrate renewables, complicates the picture. Once completed, storage would no longer be needed to ease these bottlenecks. Goran Majstorović of the Hrvoje Požar Energy Institute (EIHP), who contributed to the network analysis, points to a way through. "Once the grid capacities are in place, batteries will be deployed less for relieving bottlenecks and more for arbitrage, buying energy cheaply and selling it at a higher price," he explains. "That way, these projects will remain profitable." For investors, a two-stage business model is taking shape: congestion management as the entry point, with arbitrage as the long-term revenue pillar.
Grid expansion underway
From the perspective of transmission system operator HOPS, the study affirms the investment path already taken. "Batteries and the flexibility they will bring are certainly a good transitional instrument until the 400 kV networks are built," says Ljupko Teklić, deputy director in the sector for development, investment and planning at HOPS.
Ultimately, though, there is no way around grid expansion. That position is not an entirely neutral one. Around €335 million in non-repayable funds has already flowed into raising connection capacities through the national recovery programme alone, Teklić notes, with Dalmatia in particular, the very corridor on which investor interest in storage is concentrated, already seeing substantial grid investment.
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The study reaches well beyond technical analysis. It shows that batteries can be built on the back of a business model that has so far drawn little attention from decision-makers in Croatia: relieving grid congestion. Branimir Ivković, head of the hydropower division at green power developer Encro, makes the point from a developer's standpoint. "This makes the study a methodological step forward, away from outdated outlook scenarios and toward genuine grid analyses that do justice to real market dynamics," he says.
Solar plants adding storage
That dynamic has now reached the project level. Josip Tošić, director of Toska, a consultancy specialising in renewable energy, reports that the Croatian renewables market has fundamentally shifted. "Realistically, there is virtually no renewable energy project today, particularly no solar power plant, where battery storage is not integrated from the early planning phase," he says. Solar projects without storage are barely financially viable any longer, and existing plants are being retrofitted in numbers. According to Tošić, standalone storage units, which take on precisely the congestion business described in the study, are drawing particularly strong investor interest. (su)
