Bulgaria has started construction of a 300 MWh battery energy-storage facility at Tvarditsa. The project is the first stage of a broader programme valued at more than €350 million. The wider plan includes three battery projects with combined storage capacity of more than 2.3 GWh.
Tvarditsa battery project details
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.
Role in balancing and wholesale price dynamics
Battery investment across Bulgaria has accelerated as rising solar and wind capacity changes the country’s intraday power balance. New storage is expected to take up surplus renewable electricity during high-output periods. It would then return electricity to the grid when production declines or demand rises.
The programme 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.
Additional flexibility options and trading implications
Bulgaria is also considering additional storage, pumped-storage hydro and generation investments as it modernises the electricity system. These measures are intended to create more flexibility for renewable projects. The emerging battery fleet could support Bulgaria’s position 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. For investors, the rollout reflects a shift toward storage as a standalone element of Bulgaria’s electricity-market infrastructure.