NLC India (NLCIL) has issued an engineering, procurement, and construction (EPC) tender for setting up a 250 MW/500 MWh battery energy storage system (BESS) project at the Tamil Nadu Transmission Corporation’s Annupankulam, Ottapidaram, and Kayathar substations.

Bids must be submitted by January 30, 2026. Bids will be opened on the same day.

Bidders must furnish an earnest money deposit of ₹67.33 million (~$743,800) and a document fee of ₹20,000 (~$225).

Selected bidders must submit a BESS life cycle performance guarantee of 8% of the contract value.

The scope of work entails the design, engineering, manufacturing, erection, testing, and commissioning of the BESS project. It also entails providing operation and maintenance (O&M) services for 12 years.

The BESS must have a minimum round-trip efficiency of 87% for its first operational year and 85% from the second to the 12^th year. It must demonstrate a system availability of 95%.

Successful bidders must undertake the project’s civil works. This includes providing the free issue items, services, and performance demonstrations with associated equipment and materials on a turnkey basis.

Selected bidders must pay the registration and statutory inspection fees for the project. They must also provide all equipment and materials required to implement reactive power compensation systems/harmonic filters.

They must reroute the existing utility transmission lines, undertake area grading and filling, and construct the approach road to the project’s lease land.

Selected bidders must obtain the approvals, permits, and clearances from the local administrative or statutory body for the BESS project. This would include environmental clearances, land-use permits for the project and its transmission system, access, and water for construction and O&M activities.

They must also obtain approval from the Central Electricity Authority or other statutory authorities before charging the BESS.

The scope of work also includes a 12-year warranty for the BESS project’s works and equipment, including a five-year power conversion system warranty. It also involves providing technical personnel or specialists from multiple disciplines to supervise the project’s construction and commissioning.

Commissioning delays will attract damages of 0.5% of the total contract price, excluding O&M, per week of delay, capped at 5%. System availability and round-trip efficiency shortfall will also result in penalties.

Bidders must have manufactured and supplied batteries of at least 80 MWh for BESS. At least one of the supply orders must have been for 20 MWh. The BESS must have been operational for a minimum of six months before the bid opening date.

Alternatively, they must have supplied, installed, or supervised installation, and commissioned or supervised the commissioning of a BESS of at least 80 MWh capacity. At least one BESS must have a minimum capacity of 20 MWh. These systems must have been operational for at least six months before the bid opening date.

bidders who have designed, supplied, erected, or supervised the erection, and commissioned, or supervised the commissioning of solar or wind projects of at least 100 MW capacity in a single work or project are also eligible to bid. These projects must have been operational for at least one year before the bid opening date.

Bidders who have executed a single industrial project or work in the power, steel, oil and gas, petrochemical, fertilizer, cement, coal mining, including coal handling, or any other process sectors in the last 10 years as a developer or an EPC contractor can also participate in the tender. The project must have been worth at least ₹1.4 billion (~$15.51 million). Renewable energy projects must have been operational for at least six months, and non-renewable energy projects for at least one year before the bid opening date.

Under this requirement, bidders must have executed at least one electrical substation of a minimum 33 kV voltage level as a developer or an EPC contractor. The substation must have consisted of voltage level circuit breakers of at least 33 kV and power transformers. Renewable energy substations must have been operational for at least six months and non-renewable substations for at least one year before the bid opening date.

Bidders must have a positive net worth. They must have a minimum average annual turnover of ₹1.4 billion (~$15.51 million) during the last three consecutive financial years.

In November 2025, the Tamil Nadu Green Energy Corporation (TNGECL) invited bids to set up a 15 MW solar power project with a 15 MW/45 MWh BESS in Karur, Tamil Nadu.

In the same month, TNGECL invited bids to set up seven standalone BESS with a total capacity of 375 MW/1,500 MWh.