The study reviewed the mainland grid, focusing on 230 substations and 453 transformers. It found that transformers with high photovoltaic output are best suited for connecting standalone batteries, as solar generation follows a more predictable production profile than variable sources such as wind and hydropower. Co-locating batteries with areas of high PV penetration can significantly reduce grid congestion. Using this methodology, 70 substations were identified as priority locations for merchant batteries under the Ministry of Environment and Energy’s invitation for connection terms. These substations meet the criterion of high photovoltaic production, enabling storage units to act as an effective “antidote” to congestion.
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The study also points to an uneven geographical distribution of battery capacity. Regions such as Epirus and the greater Athens area show limited potential due to fewer transformers or lower PV penetration. By contrast, central Greece and central Macedonia could host nearly double the battery capacity, reflecting high installed PV capacity and available electrical headroom. However, the analysis indicates that increasing battery power does not always deliver proportional grid benefits. Beyond a certain level, additional congestion relief becomes marginal. On this basis, the study identifies an optimal storage portfolio of 1.15 to 1.7 GW.
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The findings support a robust expansion of battery installations, driven by the dominance of photovoltaics. By the end of 2025, 9 GW of renewables were installed on the Greek distribution network, including 7.2 GW of solar, while the transmission system hosted 8.1 GW of renewables, of which 3.7 GW were photovoltaic. (Kostas Deligiannis/hcn)
This article was first published on the Greek energy news portal Energy Press.
