India plans 2-hour battery storage mandate for new solar, wind projects

India is preparing to make battery storage a mandatory part of new solar and onshore wind projects, marking a significant shift in how the country plans to manage its rapidly expanding renewable energy capacity.

Under draft regulations prepared by the Central Electricity Authority (CEA), new solar and onshore wind projects commissioned from July 1, 2027 would have to provide battery storage equivalent to at least 10 per cent of their installed capacity, with the storage system capable of supplying power for a minimum of two hours, Reuters reported.

The proposal comes at a time when India is adding renewable capacity at a rapid pace but is also confronting a new problem: having more clean electricity available at certain times than the grid can absorb or transport.

The storage requirement is designed to address that mismatch. Instead of allowing surplus solar or wind power to go unused, batteries can store electricity when generation is high and release it when demand rises or renewable generation falls.

Storage mandate to double duration from 2029

The proposed rules would become more stringent from July 2029.

The minimum storage duration would then increase from two hours to four hours, while the requirement for storage capacity equivalent to at least 10 per cent of the project’s installed capacity would remain.

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The move would make energy storage an integral part of new renewable projects rather than relying entirely on the transmission network or other power sources to balance fluctuations in generation.

For solar power, the need is particularly evident. Generation typically peaks during the middle of the day, while electricity demand can remain high or rise later in the evening when solar output starts falling.

Battery storage can bridge that gap by shifting a portion of daytime renewable generation to periods of higher demand.

India curtailed nearly 14% of solar output

The urgency of the issue is underscored by the amount of renewable electricity already being curtailed.

India curtailed nearly 14 per cent of its solar power generation between April and June, according to the Reuters report. Surplus electricity during daylight hours, combined with constraints in the transmission network, meant that some available solar power could not be absorbed by the grid.

Curtailment effectively means reducing renewable generation even though a solar or wind plant is capable of producing electricity.

New renewable projects may also need grid-forming inverters

Clean-energy projects commissioned after July 2027 would also be required to have grid-forming inverter capabilities, according to the draft.

Grid-forming technology can help renewable and battery-based power systems support grid stability by helping maintain voltage and frequency.

That capability is becoming increasingly important as renewable sources account for a larger share of electricity generation.

Conventional power plants, particularly those using synchronous generators, provide physical characteristics that help stabilise the electricity grid. Solar and wind projects generally connect to the grid through power-electronic inverters and do not provide those characteristics in the same way.