One of the main bottlenecks for large-scale solar and wind projects in Croatia is the national grid. While this is not a unique challenge, the country’s geography makes it more pronounced, and adding more renewable capacity would likely lead to significant lost generation. Strategically placed large-scale storage systems could help reduce these constraints.
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This is one of the findings of a storage study presented by Dražen Balić of the Energy Institute Hrvoje Požar and Miroslav Holjevac of the University of Zagreb at this year’s SolarFlex Croatia conference in Zagreb. The researchers assessed three scenarios, looking at investment costs, potential savings and how much additional solar and wind capacity the grid could absorb once storage is in place, without losses. This assumes the storage systems are built with the capacity, output and locations defined in the study.
Daily buffering of one gigawatt hour
Given the current state of Croatia’s power system and grid, the proposed batteries would buffer around one terawatt hour of electricity per year. This would allow an additional 600 gigawatt hours of renewable power to be absorbed by the grid. Annual curtailment would fall by around 60 hours.
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If solar and wind capacity is expanded in line with legally defined targets, storage systems, alongside grid expansion, would need to buffer around 365 gigawatt hours per year. In this scenario, an additional eight gigawatt hours of solar and wind generation could be absorbed by the Croatian grid. Overall, curtailment due to grid bottlenecks would fall by around 1,100 hours per year. Dražen Balić estimates the required investment in storage at around €175 million, the lowest across the three scenarios.
30,000 more hours of green power feed-in
If all approved solar and wind projects, with a combined capacity of 1.62 GW, were built, the required investment in storage would rise to €1.24 billion. However, this scenario also delivers the greatest savings. The batteries would buffer around two terawatt hours of electricity, preventing roughly 30,000 hours of curtailment. This would allow an additional 170 gigawatt hours of solar and wind generation to be fed into the grid.
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Electricity prices becoming more stable
This would have a direct impact on electricity price stability in Croatia, which is key to the economic viability of solar parks. “We found that battery storage reduces the price decline on the power exchange, which directly affects the profitability of solar power plants,” says Dražen Balić, the study author. Storage systems prevent prices from dropping sharply during midday hours. Even if all planned solar projects are built, shifting feed-in through storage would raise midday prices by around 25 percent, improving revenues for solar operators.
The full study, currently available in Croatian, can be downloaded from the website of the Croatian Renewable Energy Association (OIEH). An English version is in preparation. The first part of our series examines optimal locations for battery deployment, while the second looks at the commercial operation of storage systems. (su)
