Translated from article:

Interestingly, in the hours with zero or negative prices, Bulgaria continues to import electricity, which is also used to charge batteries and the pumped hydro storage power plants. And later, at the evening peaks of consumption, he sends it back to neighboring countries, but at a much higher price. ENTSO-E (Bulgarian network operator) data does not show the batteries directly, but the balance sheet profile of the system in May 8-14, 2026 clearly shows their role. At midday hours between 11 a.m. and 15 p.m., a positive remainder of about 27 GWh appears in the system - energy that is not seen as consumption or export. In the evening, between 18 and 23 p.m., the reported generation is no longer enough to cover both consumption and physical exports, with “missing” energy being about 33 GWh. It is these invisible consumers and manufacturers that are the batteries - as here we are talking about the self-installed ones, because the storage systems to solar parks are seen as solar production when they return electricity to the network.