India Proposes Mandatory Storage for New Solar, Wind Projects From July 2027
India’s Central Electricity Authority or CEA has proposed mandatory co-located energy storage for new ground-mounted solar and onshore wind projects commissioned after July 1, 2027.
The Sept. 3 draft amendment to CEA’s construction standards would require storage power capacity equivalent to at least 10% of a plant’s installed capacity, with a minimum two-hour duration.
For projects commissioned after July 1, 2029, and by June 30, 2031, the minimum duration would rise to four hours, while the 10% power requirement would remain unchanged.
The draft would also require grid-forming controls for at least 15% of inverters at renewable plants commissioned after July 1, 2027, as well as for all battery storage power conversion systems. CEA is accepting comments on the proposal until Oct. 4.
The proposal builds on CEA’s February 2025 advisory recommending co-located storage in solar tenders. The authority said storage could make solar power available during non-solar and peak-demand hours, strengthen grid reliability and improve the use of transmission infrastructure beyond daylight hours.
Curtailment pressure
The proposal comes amid rising grid constraints that have increasingly forced some solar plants to curtail output.
In a July 28 parliamentary reply, the Ministry of New and Renewable Energy, or MNRE, reported that 8,133 gigawatt hours of solar energy were curtailed between April and June this year.
The curtailed volume was equivalent to approximately 13% of solar generation recorded by CEA during the same period, according to OPIS calculations, or enough to meet the annual electricity needs of roughly 7 million Indian households, based on household consumption estimates from energy think tank Ember.
The ministry attributed the curtailment to grid-security constraints and mismatches between the commissioning of renewable projects and transmission infrastructure.
Solar generation is concentrated in the daytime, when output can exceed electricity demand or the grid’s capacity to transmit the power to where it is needed, a developer source said. Without storage or another outlet for the excess power, plants may have to limit output, leaving potential generation unused and reducing revenue, the source added.
Compounding cost pressures
Some market participants said the proposed storage mandate could compound cost pressures for utility-scale solar projects that will also be subject to domestic-cell sourcing requirements under India’s Approved List of Models and Manufacturers or ALMM.
Competitively bid projects covered by ALMM with final bid-submission deadlines after Aug. 31, 2025, must use modules containing domestic cells listed under ALMM List-II.
A manufacturer source expected “a large wave” of utility-scale demand for domestic-cell modules to begin in early 2027, as projects subject to the requirement enter the procurement stage. Projects commissioned after July 1, 2027, could also fall under the proposed storage mandate if adopted.
Modules using domestic cells are expected to command a premium over those using imported cells in the near term, amid tight domestic cell supply, according to the source. As of Aug. 7, India had about 32GW of domestic cell manufacturing capacity listed under ALMM List-II, compared with approximately 213GW of module manufacturing capacity under List-I, according to MNRE.
According to OPIS, spot indications for India-assembled TOPCon modules using imported cells stood at INR13.95 per watt peak ($0.146/wp), ex-works India, compared with INR22.10-25.20/wp for those using domestic cells. For mid-2027 delivery to utility-scale projects, offers for domestic-cell modules were heard at INR18-19/wp.
One market participant, however, said storage should not be viewed solely as an added cost burden. Projects facing recurring curtailment could recover part of the investment by storing electricity that would otherwise be curtailed and selling it during periods of low renewable generation, the source said.
The proposed mandate would also come as procurement increasingly shifts toward storage-backed renewable power. MNRE has said declining costs for solar-plus-storage and dispatchable renewable power are shifting buyer preferences away from standalone solar, prompting renewable-energy implementing agencies to issue more tenders for storage-backed, peak-hour and firm renewable supply.
—Reporting by Jun Won Lee, jun.lee@dowjones.com; Editing by Mei-Hwen Wong, mei-hwen.wong@dowjones.com