The Brihanmumbai Electric Supply and Transport undertaking has signed a 25-year power purchase agreement with the Solar Energy Corporation of India for 220 megawatt (MW) of solar power backed by a 110 megawatt (MW)/440 megawatt hour (MWh) energy storage system (ESS).

The pact, concluded on 31 August, will supply power at Rs 2.87 per unit and aims to expand BEST's green energy portfolio. The arrangement will add firm renewable capacity to the city's supply mix and provide dispatchable energy through storage.

The storage system will allow electricity to be stored during periods of low demand and released in evening peak hours, helping to moderate volatility in procurement costs. Renewable energy will be sourced from multiple project developers in Maharashtra under the agreement. The agreement forms part of BEST's efforts to meet its renewable purchase obligation targets and to reduce dependence on conventional thermal plants.

BEST currently meets around 33 per cent of its total electricity requirement of nearly 1,000 MW through renewable sources and the new capacity is expected to raise that share to 43 per cent. The availability of stored power during peak demand windows should lower the average cost of procurement at critical times and reduce reliance on higher cost peak supplies. System operators will be able to optimise dispatch schedules to align storage discharge with periods of elevated grid prices, improving cost efficiency.

The agreement was signed by senior officials from both BEST and SECI and runs for 25 years, providing long term visibility for planning and investment. Apart from savings on power procurement, the initiative is expected to contribute to lowering carbon emissions and to strengthen BEST's shift towards cleaner energy sources. The procurement price and storage arrangement are intended to support a more resilient and cost effective supply for the city.