The second largest source of energy in Bulgaria after the Kozloduy Nuclear Power Plant (NPP) in May was solar parks. This is not a surprise, but rather a growing trend. Investments in solar power and energy storage systems are significantly increasing the share of solar power, which now accounts for 25.1% of total production.
Overall, green energy (solar, wind, hydroelectric, biomass, and waste) accounted for 43.2% of the country's energy mix last month. For comparison, this is exactly the same as last June's record, but it comes a month earlier. At the same time, the share of coal-fired thermal power plants fell to 18.9%, which is similar to last year's data.
Of course, these percentages also depend on the capacity at which the Kozloduy NPP operates. However, in this case, as in the previous year, the scheduled repair of one of its units began on May 5, and in fact, the system operated without it for almost the entire month. Despite this, the share of nuclear energy remains at around 33%.
The advance of RES
According to data from the Agency for Sustainable Energy Development (ASED), renewable energy production capacities in Bulgaria are now 7,400 MW, which is the most compared to all other power plants. However, since they cannot operate continuously, this capacity is not fully utilized.
Nevertheless, the share of green energy continues to increase and, despite concerns that this leads to difficulties in managing the electricity system, there are no signs that this process will stop anytime soon.
Solar parks already have a capacity of more than 4,200 MW and, on a sunny day, at least in theory, they can easily meet 100% of the country's needs, even if no other power plant is operating. In May, they generated 604 GWh, compared to 454 GWh produced by coal-fired thermal power plants and 794 GWh by nuclear power plants.
With the mass installation of batteries in solar parks, their efficiency will increase because, instead of stopping operation due to zero prices on the exchange or due to excess energy in the grid, they will be able to store and sell in the evening or morning. According to unofficial data, there are already about 1,000 MWh of energy storage systems in operation in Bulgaria, which could increase the monthly solar production of existing capacities by another 5%. However, it is expected that by March-April 2026, battery capacity will reach 6,000 MWh, which would allow for a 30% increase in production, not counting the new power plants that are expected to come online by then.
However, the situation is quite the opposite for other renewable energy sources. There are still no new wind power projects that will become operational in the next year or two, and there has been no real change in this area over the last decade. There are no new hydroelectric power plants either, but due to the drought, electricity production remains critically low. Even this year, when there was supposedly more rainfall, the activity of hydroelectric power plants is 30% lower than in May 2024. On average, production for the first five months of the year is also lower by the same amount.
Coal without a market
Average electricity prices on the exchange have stabilized over the last two months at around 160/MWh levs. This is good for business consumers, but, in reality, it does not allow coal-fired power plants to sell their energy freely. Without state intervention (purchasing under contracts or subsidizing the regulated market), their operation would be almost impossible.
This is why total coal-fired power generation fell significantly in May, reaching one of its lowest levels ever. This decline will inevitably continue in June, while in July the new energy model for the regulated market will come into force and it is currently unclear how exactly the Maritsa East 2 Thermal Power Plant will fit into it.
Will the grid hold up?
The major concerns about the dynamic changes in electricity production are related to the grid. This became particularly relevant after the massive power outage in Spain, which left the entire country without electricity for hours.
It is becoming increasingly common for around 60% of the energy during the day to be supplied by photovoltaic and wind turbines, which at present (due to the lack of sufficient batteries) cannot provide the necessary parameters to balance the system. According to Energy System Operator (ESO) experts such as Ventsislav Zahov, head of the Electrical Regimes Department at the Central Dispatch Office, the increase in the share of asynchronous power can create problems and power outages. However, energy analyst Simeon Beloreshki believes that these are outdated ideas about system management and that the system can function very well with a large share of RES and batteries.
It is likely that we will see whether this is the case in the fall.
The second largest source of energy in Bulgaria after the Kozloduy Nuclear Power Plant (NPP) in May was solar parks. This is not a surprise, but rather a growing trend. Investments in solar power and energy storage systems are significantly increasing the share of solar power, which now accounts for 25.1% of total production.
Overall, green energy (solar, wind, hydroelectric, biomass, and waste) accounted for 43.2% of the country's energy mix last month. For comparison, this is exactly the same as last June's record, but it comes a month earlier. At the same time, the share of coal-fired thermal power plants fell to 18.9%, which is similar to last year's data.
