India’s CERC proposes new Grid Code rules for standalone BESS

The draft would require at least 15% of inverters to have grid-forming capability, while ground-mounted solar and onshore wind projects would need co-located ESS equal to at least 10% of capacity, with storage duration rising from two to four hours from July 2029.

50MW minimum trial run proposed for standalone ESS

Under the draft, a standalone ESS would generally have to complete a successful trial run for an aggregate capacity of at least 50MW.

The proposal provides flexibility for larger projects to demonstrate their capacity in stages.

For standalone ESS above 50MW and below 250MW, the balance capacity could be trialled in up to three instalments, with each instalment having a minimum capacity of 5MW.

For projects of 250MW and above, trial runs could be conducted in instalments of at least 50MW, with no limit on the number of instalments.

The draft also contains a specific provision for certain standalone ESS below 50MW that have been granted connectivity under the applicable GNA provisions, allowing their trial run to be conducted at the granted connectivity capacity.

The staged approach is significant for India’s emerging large-scale BESS market because it separates the requirement to demonstrate technical performance from a one-time test of an entire project.

Storage brought into primary frequency response framework

The draft also proposes a more explicit role for qualifying ESS in primary frequency response.

Standalone ESS of 10MW and above, connected at 33kV and above, would be included in the relevant provisions for primary frequency response, subject to the applicable Central Electricity Authority technical standards.

The proposed framework specifies a droop-setting range of 0–10% for ESS frequency controllers, subject to CEA standards.

The draft also provides for the National Load Despatch Centre (NLDC) to issue instructions relating to frequency-response obligations.

The proposal is important because it moves qualifying storage beyond its traditional treatment as an energy-shifting asset and explicitly addresses its capability to respond to grid-frequency conditions.

However, the draft should not be read as meaning that every BESS project will automatically be required to participate in every ancillary-service product. The precise operational obligations and compensation arrangements will depend on the applicable grid and ancillary-service frameworks.

25MW threshold for automatic operation

A separate provision would require standalone ESS of 25MW and above, excluding pumped storage plants, to have the capability to support automatic operation from the relevant load-dispatch centre.

This creates another operational distinction between smaller storage projects and larger grid-connected systems.

For BESS developers, the provision raises questions around communications, supervisory control and data acquisition systems, inverter controls and the extent to which projects will need to support automated dispatch or other control functions from system operators.

Separate rules proposed for pumped hydro

The draft also proposes a separate set of commissioning and commercial-operation provisions for pumped storage plants (PSPs), reflecting the different testing requirements associated with reservoir levels, pumping and turbine operation.

For PSPs, CERC proposes allowing short interruptions or load reductions during trial runs, with the test duration extended correspondingly. Average loading would still have to remain at least at the applicable minimum continuous rating, excluding the interruption period but including the extended test period.

If cumulative interruptions across pumping and turbo-generator modes exceed four hours, the trial run would have to be repeated.

The draft also addresses a practical issue specific to pumped hydro: insufficient reservoir levels during commissioning. Where a PSP cannot demonstrate its design capability at the rated water-drawing level because adequate water is not available, commercial operation could be declared after demonstrating capability at the available water level, subject to subsequently demonstrating the full design capability once sufficient reservoir levels are available.

The proposal further sets out a separate commercial operation date (COD) framework for PSP units. COD of an individual unit would be linked to a successful trial run at its maximum continuous rating (MCR) or de-rated capacity and submission of the required declaration, while the COD of the final unit would be treated as the COD of the entire plant.

The draft also proposes provisions for PSPs of 25MW and above under the specified connectivity framework and addresses cases where transmission constraints prevent a plant from demonstrating its rated capacity within the prescribed period.

Together, the PSP provisions show that CERC is seeking to establish technology-specific commissioning rules for storage rather than applying the same trial-run framework to battery and pumped storage projects.

This comes against the backdrop of India targeting 100GW of pumped storage capacity by 2035-36, with the International Hydropower Association (IHA) estimating nearly 288GW of potential in the country.

Grid-code COD linked to successful trial run

The draft also proposes to link commercial operation under the Grid Code to successful completion of the relevant trial run.

For ESS, COD would be considered in accordance with the Grid Code following successful completion of the trial run. The draft nevertheless preserves a distinction between regulatory COD and contractual conditions: where a power purchase agreement or other contract contains additional conditions for supply of power, those conditions would continue to apply.

The draft separately addresses infirm power.

Scheduling of infirm power from an ESS would only be permitted after successful completion of the trial run. Where the applicable contract specifies how power generated or injected before commercial operation is to be treated, those provisions would apply.

If the contract does not specify such treatment, the power would first be offered to contracted buyers with at least seven days’ notice. If buyers do not respond, the draft would allow the developer to sell the power to a third party.

More flexibility — but also more reporting — for commissioning delays

The draft proposes a specific process where an ESS is unable to commence commissioning within the prescribed timeframe.

The project would have to provide detailed reasons for the delay, along with its likely date of commencement, and request an extension at least 10 days before the proposed commencement date.

The regional load despatch centre could grant multiple extensions, subject to a cumulative maximum of three months. The project would also be required to provide monthly updates.

The approach gives developers a formal mechanism for dealing with commissioning delays while imposing additional reporting requirements.

The proposal comes amid wider efforts by CERC to improve utilisation of India’s constrained transmission infrastructure.

Wider grid reforms include congestion and payment defaults

The ESS provisions sit within a much broader amendment to the IEGC.

CERC has proposed a new congestion-charge mechanism under which entities contributing to transmission congestion could be charged, while entities helping relieve congestion could receive payments.

The draft also proposes tighter consequences for certain payment defaults, including defaults relating to deviation settlement mechanism, congestion or reactive-energy charges and failures to maintain required payment security.

For specified contracts, access could be progressively reduced by 5% per month where dues remain unpaid, subject to the conditions in the draft.

Separately, CERC proposes changes to scheduling revision timelines, with the second phase of the proposed reduction taking effect from 1 April 2027.

For storage developers, these provisions matter because the regulatory framework around BESS is increasingly extending beyond project connection and market access to include detailed requirements for commissioning, system operation and grid services.

The draft remains a proposal and could change following stakeholder comments before CERC finalises the amendment.

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