Ember research found that South India recorded no curtailment even as India logged 300 GWh of renewable energy losses in Q1 2026. The study, which measures output in gigawatt-hour (GWh) and capacity in gigawatt (GW), attributed about 470 GWh of inter-state curtailment in Q1 2026 to a mix of transmission constraints and system inflexibility, with roughly 300 GWh linked directly to transmission. The report noted that the Northern and Western regions accounted for the bulk of congestion.

Transmission expansion has consistently trailed targets, with completed additions at about 80 per cent over the past five years, the study said. India requires 61,411 circuit kilometres of additional Inter-State Transmission System (ISTS) capacity by FY2029–30, yet one in four major transmission schemes is delayed by a year or more and nearly 20 GW of renewable capacity faces connectivity delays exceeding four months in FY2026–27. These connectivity shortfalls impose material financial costs because projects under Temporary-General Network Access (T-GNA) do not receive compensation during curtailment and typical project delays can reduce internal rates of return by 100–200 basis points.

Battery energy storage systems (BESS) at renewable pooling stations were identified as the most credible near-term remedy to ease congestion, but deployment has been hindered by absent regulatory frameworks and weak commercial incentives. Ember proposed an intermediary government-backed entity to aggregate output from T-GNA projects and contract it to BESS developers, which would reduce contracting risk for transient projects. The report also recommended treating BESS as a transmission asset with capacity payments socialised across states in the same manner as transmission charges.

The analysis noted that falling storage costs strengthen the economic case for renewable-plus-storage solutions and that roughly three to four GW of two-hour storage capacity could absorb most curtailed generation. It highlighted nearly 236 GW of plug-and-play BESS connectivity headroom at major pooling stations and reported that the levelised cost of storage has fallen to around Rs 4.0–4.5/kWh while solar generation is near Rs 2.5/kWh, yielding combined delivered costs well below the Rs 10/kWh many states pay for peak procurement. The study urged co-optimised planning of transmission and project siting and recommended mandatory co-location of storage to reduce persistent congestion.