TERI Tenders 55.5 MW/111 MWh BESS Projects With Grid-Forming Inverters for BRPL

The Energy and Resources Institute (TERI) has issued two standalone Battery Energy Storage System (BESS) tenders for BSES Rajdhani Power. The tender aims to develop two BESS projects: a 43 MW/86 MWh system at a 66/11 kV substation located at Goyla Khurd Grid. Along with this tender also intends to develop a 12.5 MW/25 MWh system at a 33/11 kV substation located at the Shivalik Grid Station. This is one of the few tenders that includes the use of grid-forming inverters. It has sought bids for the project till December 30, 2025. A grid forming inverter is different from a grid following inverter, as is usuyally the case in India. 

Grid-forming inverters create and stabilize the grid’s voltage and frequency, acting like traditional synchronous generators, while grid-following inverters depend on an existing grid signal to synchronize and inject power. Thus, grid forming inverters can actually support the grid by varying output, even as grid following inverters can actually make it worse, as they are designed to protect the system they are running, and will even switch off at the first sign of instability.  

Thus, the 12.5 MW tender also includes grid support functionality in the BESS project that is connected to the Goyla Khurd Grid project through the use of grid-forming inverters. For the BESS project connected to the Shivalik Grid Station, the tender includes the use of both grid-following and grid-forming capability.

Under the scope of the tender, bidders are required to carry out site surveys, planning, design, engineering, procurement, transportation, and supply to the site, insurance, unloading, handling, installation, integration, testing, commissioning, and O&M of the BESS in line with the technical specifications.

TERI clarified that BRPL has shortlisted project locations within its licensed area in Delhi. The primary application is energy arbitrage/peak shaving, while the secondary application is frequency support as an ancillary service. The tender also notes the use of energy time-shifting (arbitrage), ramping support, ancillary services, blackout support, and reactive power support.

Scope of Work

The tender specifies that the BESS project will be executed by the Battery Energy Storage Developer (BESSD) for over 12 years. The system is designed for two cycles per day and will be developed under a BOOT model, with the asset to be handed over at 70% residual capacity at the end of the contract. BRPL will handle BESS charging, and an allowed degradation rate of 2.5% has been set.

The commissioning timeline includes an initial seven-month period, followed by an additional six months with penalties applied from the effective date of the agreement. The system will be considered commissioned only after a successful seven-day trial run and submission of all required test reports. The quoted tariff will be in INR per MW per year, and the BESS must maintain a minimum monthly availability of 95%, with penalties imposed at 1.5 times for any shortfall.

Round-trip efficiency will be graded over the 12 years, starting at 86.78% in year one and declining to 85.36% in year twelve, with penalties linked to the APPC. One full cycle will be counted when the cumulative energy added to the storage facility within a month equals the maximum storage level.

Financial assistance will be provided only for the 12.5 MW/25 MWh system to cover the incremental cost of upgrading inverter technology from grid-following to grid-forming.