The Bihar Electricity Regulatory Commission (BERC) has ruled in favor of Bihar State Power Generation Company Limited (BSPGCL) in a dispute over the grid connectivity capacity for a hybrid renewable energy project at Kajra in Lakhisarai district. The decision provides clarity on how transmission connectivity should be determined for hybrid projects that combine solar power generation with battery energy storage.
The case involved an 185 MW solar photovoltaic (PV) plant integrated with a 45.4 MW Battery Energy Storage System (BESS). BSPGCL approached the commission after the Bihar State Power Transmission Company Limited (BSPTCL), acting as the State Transmission Utility (STU), insisted that the project should obtain connectivity for a total capacity of 230.4 MW by adding the installed capacities of both the solar plant and the battery system.
BSPGCL argued that the project has been designed to operate on a non-overlapping basis. During daytime, the solar plant generates electricity for the grid while using around 20 percent of its output to charge the battery storage system. Once solar generation stops in the evening, the battery discharges the stored energy to the grid during peak demand hours. Since the solar plant and the battery never export electricity to the grid simultaneously, the project’s maximum power injection at any point remains limited to 185 MW.
The company also pointed out that the project is equipped with transformers having a maximum capacity of 200 MVA. This technical limit makes it impossible for the plant to inject 230.4 MW into the grid at the same time. BSPGCL stated that requiring connectivity for a higher capacity would unnecessarily increase its financial burden through larger bank guarantees and higher transmission charges for capacity that the project can neither use nor deliver.
BSPTCL defended its position by stating that connectivity should be based on the total installed nameplate capacity of all generation assets. It also raised concerns that under exceptional conditions, such as grid disturbances or faults, simultaneous power injection could occur if adequate safeguards were not in place. The utility further noted that the Power Purchase Agreement (PPA) allows flexibility in scheduling battery discharge, which could potentially result in power being supplied outside the originally planned operating window.
After examining the submissions, BERC rejected the transmission utility’s approach of simply adding the capacities of the solar plant and battery system. The commission observed that connectivity for hybrid projects should be determined by the maximum instantaneous power that can actually be injected into the grid, rather than by the sum of the installed capacities. It also stated that concerns about possible grid instability must be supported by technical studies or evidence and cannot be based on assumptions alone.
Accordingly, BERC directed that the project’s grid connectivity capacity be revised to 185 MW. At the same time, the commission instructed BSPGCL to submit a formal declaration or enter into a supplementary agreement with BSPTCL specifying the operational limits and charging and discharging schedule of the battery system. This requirement is intended to ensure safe, transparent, and efficient operation of the hybrid project while protecting the reliability of the state transmission network.
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