Bulgaria has started construction of a 300 MWh battery energy-storage facility at Tvarditsa. The project is described as the first stage of a wider programme valued at more than €350 million. The programme includes three battery projects with combined storage capacity of more than 2.3 GWh.
The Tvarditsa installation is being developed by Asarel-Trade and Power Profit using Tesla technology. The facility will use 80 Tesla Megapack 2XL units and 20 transformers rated at 4.4 MVA. It is designed to provide around five hours of discharge capability.
Storage expansion linked to changing intraday power balance
Battery investment has accelerated across Bulgaria as rising solar and wind capacity changes the country’s intraday power balance. New storage is expected to take in surplus renewable electricity during high-output periods. It would then return electricity to the grid when production declines or demand rises.
The additional storage capacity is expected to reduce balancing requirements and limit some of the increasingly sharp wholesale-price swings linked to high renewable penetration. Once completed, the three-project programme is expected to deliver more than 2,300 MWh of storage.
Broader flexibility plans and regional trading implications
Bulgaria is also considering additional investments in storage, pumped-storage hydro and generation as it seeks to modernise the electricity system and increase flexibility for renewable projects. The emerging battery fleet could support Bulgaria’s role as an electricity-trading hub in Southeast Europe.
This would be particularly relevant during periods when solar output creates large daytime surpluses followed by steep evening ramps. The rollout is positioned as a shift from storage supporting renewables to storage forming part of Bulgaria’s standalone electricity-market infrastructure.