Energy think tank Ember has identified that India needs approximately 10 GWh of battery storage to effectively manage renewable energy curtailment and grid stability. According to the report, this storage capacity would be sufficient to absorb excess solar generation during midday hours, allowing coal plants to operate above their minimum technical limit (MTL) of around 55 per cent capacity. The storage would enable grid operators to avoid curtailing clean electricity while maintaining thermal power plant availability for evening demand peaks. As Ember Senior Energy Analyst Neshwin Rodrigues explains, "Solar and wind curtailment is becoming a visible part of India's real-time grid balancing, and the volumes are already noticeable and rising. Without sufficient flexibility, including storage, this could become a constraint on the next phase of renewable energy growth."
The report reveals that keeping coal plants above their MTL forced the curtailment of around 2.1 terawatt-hours (TWh) of renewable generation in FY26, equivalent to 1.3 per cent of total renewable generation. As reported by Ember, solar power generation floods the grid during daytime hours, forcing coal-based power plants to operate at or below their MTL. This operational constraint leads grid operators to curtail clean electricity to ensure thermal power plants remain online for increased nighttime demand. By April 2026, coal plants were breaching their minimum operating threshold in more than half of all midday dispatch intervals, with renewable energy curtailment accounting for 37% of all down-regulation requirements compared with almost zero a year earlier.
According to the report, on March 6, 2026, solar and wind reached 41 per cent of the generation mix at midday, pushing coal down by around 49 GW in six hours before requiring a climb back by 51 GW in the evening as solar generation declined. Peak-hour curtailment had returned to 4 per cent of solar and wind generation by April 2026, comparable to the most constrained months of late 2025. The report noted that solar and wind energy curtailment due to the emergency Tertiary Reserve Ancillary Service (TRAS) down mechanism exceeded 3,600 GWh by early June 2026, from zero in mid-2025. As Rodrigues explains, "Coal was built for sustained high output, not this daily deep cycling."
The current General Network Access (GNA) framework creates significant barriers to battery storage deployment. Under the Right of First Refusal mechanism, BESS projects seeking non-solar-hour access face two conditions: a minimum two-hour storage duration and installation of commensurate renewable generation capacity for charging. Until that capacity is commissioned, grid charging is permitted only on an interim basis and within available margins. This creates delays as developers must identify land, negotiate access, and commission additional renewable generation before BESS can operate with full grid access. The framework treats two different operations as equivalent: a battery absorbing surplus generation at noon and a battery drawing power through constrained connections at night. As per Ember, this restriction is broader than the risk it manages, as it weakens price signals needed to scale storage deployment.
Citing the example of the 3.37 GWh Khavda project in Gujarat, the world's largest outside China, commissioned within 10 months, the report demonstrates that battery energy storage systems (BESS) can be deployed quickly. According to Ember, site-ready projects can be built within five to seven months. The report recommends that grid charging during solar-surplus hours be permitted by default, with withdrawal limits applied only where non-solar-hour use creates genuine network risk. However, the think tank argues that current grid connectivity regulations remain a key barrier, as existing rules often require battery projects to be paired with renewable generation before being permitted long-term grid charging, limiting their ability to absorb excess solar generation from the grid. The report notes that India's Day Ahead Market already shows prices falling to around ₹0.1/kWh during surplus solar hours and rising to ₹10–20/kWh during evening peaks, creating viable commercial opportunities for merchant storage investment.
