Vienna-based Renalfa IPP recently commissioned a 25 MW/55 MWh battery energy storage system (BESS) in Razlog, Bulgaria. This project represents the largest BESS system in operation in Bulgaria, and one of the first of this scale in Eastern Europe.
Context and importance of the project
Razlog’s BESS system is grid-connected and co-located with a 33 MWp photovoltaic (PV) power plant. The project was designed, installed and integrated by Solarpro Technology, a local company belonging to the Austrian Renalfa Solarpro Group. The main BESS components were supplied by Chinese manufacturer Hithium and energy solutions provider Kehua. According to Nick Antonov, spokesman for Renalfa IPP, “This utility battery marks the beginning of the hybridization of our portfolio of over 1 GW of renewable assets in operation and under construction. We plan to introduce similar solutions in our other wind and PV assets in the region, notably in Hungary and Romania.”
System features and management
The main aim of the storage system is to reduce the risk of PV profiles on generators. BESS is commercially managed and optimized by KER Toki Power, a local electricity trader. Thanks to the latter’s aggregation platform, the system participates in the capacity and balancing market, providing automatic (aFRR) and manual (mFRR) frequency restoration reserve services to the network. Renalfa IPP is a joint venture between Renalfa Solarpro Group GmbH and French infrastructure fund manager RGreen Invest. The company owns and develops PV, BESS and wind power projects with a combined capacity of 2 GW in Bulgaria, Hungary, Northern Macedonia and Romania. More than 455 MW are already operational and over 550 MW are under construction.
Future prospects and implications
The commissioning of this BESS system represents a crucial step for Renalfa IPP in the development of energy storage solutions in Eastern Europe. It also illustrates the growing trend towards hybridization of renewable energy production systems, combining photovoltaic installations with storage solutions to maximize grid efficiency and stability. With the planned expansion of similar projects in Eastern Europe, the role of energy storage will continue to grow, strengthening the resilience of power grids and supporting progress towards more stable and efficient energy systems. Investment in large-scale storage solutions is essential to manage fluctuations in renewable generation and guarantee a stable, reliable supply of electricity.
