Solar power paired with battery storage can deliver firm round-the-clock renewable electricity at an estimated Rs 5.15 per unit, according to a new IECC study.
The estimate is below the Rs 5.26 per unit tariff discovered in SECI’s 1,000 MW round-the-clock renewable energy auction.
The study found that a 3GW solar plant with 12GWh of battery storage could meet the tendered supply profile in Rajasthan.
Researchers said India’s stable year-round solar resource makes batteries well suited to shifting daytime solar power into evening and night demand.
Solar power paired with battery storage can deliver firm round-the-clock renewable electricity at an estimated Rs 5.15 per kilowatt hour, below the Rs 5.25 tariff discovered in the Solar Energy Corporation of India’s 1,000 megawatt (MW) auction, according to a new study.
The study, by the India Energy and Climate Centre at the University of California, Berkeley, is based on 10 years of hourly weather data across 10 Indian states.It found that a 3 gigawatt (GW) solar plant paired with 12 (gigawatt-hour) GWh of battery storage could meet the tendered supply profile in Rajasthan.
The finding comes as India seeks to make renewable power available beyond daylight hours by combining solar generation with storage. SECI’s latest tender was designed to mimic the supply profile of conventional firm power. It required developers to maintain higher supply during evening, night and morning hours, and lower supply during solar-rich midday periods.
The study said the SECI tender requires developers to supply at least 90 per cent of contracted capacity during six buyer-selected peak hours, 70 per cent during other non-solar hours and 50 per cent to 60 per cent during solar hours.
Compliance is assessed every 15 minutes, with shortfalls attracting a penalty of 1.5 times the contract tariff. The study found that increasing solar capacity to 3.5 GW while retaining 12 GWh of storage would eliminate penalties across the 10 weather years at an estimated cost of Rs 5.28 per unit.
The lowest-cost configuration was estimated at Rs 5.15 per unit, with penalties accounting for only 0.5 per cent of revenue on average. The study said the strong solar resource in northwestern India allows such systems to meet the required profile with relatively limited storage.
Jammu and Kashmir, Rajasthan and Gujarat could meet the annual obligation with 3 GW of solar and 12 GWh of storage, while other states would require about 3.5 GW of solar capacity, it found.
Umed Paliwal, Director of Modelling and Analytics at IECC and lead author of the study, said India’s relatively stable year-round solar resource was particularly suited to battery storage. “A key reason is India’s relatively stable year-round solar resource, which is especially well suited to batteries,” Paliwal said. “India’s main challenge is shifting abundant daytime solar into the evening and night, a task suited to mature, low-cost batteries.”
The SECI auction attracted bids from 16 companies, with seven developers securing capacity. Their tariffs ranged from Rs 5.25 to Rs 5.26 per unit.
Santosh Sarangi, Secretary in the Union Ministry of New and Renewable Energy, said at an industry energy conference earlier this month that the auction had shown that renewable generation combined with storage could provide firm power at a competitive tariff.
“We expected the price to be very high, but thanks to the competitive spirit among our developers, we discovered a rate of Rs 5.25 only per unit for RE RTC,” he said.
Nikit Abhyankar, Co-Faculty Director of IECC and a co-author of the study, said the narrow spread among winning bids suggested that the Rs 5.25 tariff was not an outlier. “Seven winners came in within one paisa,” he said.
The study compared the tariff with seven coal power purchase agreements signed in 2025, which started at Rs 5.38 to Rs 6.30 per unit. By contrast, the SECI contract remains fixed at Rs 5.25 per unit for 25 years.