Figures released Monday show that roughly 1.8 billion kilowatt-hours of electricity generated from renewable sources were blocked from entering the grid during July and August, held back through curtailment at a point when coal inventories at power plants had thinned and overall consumption was running at its highest levels on record.

Data from the Centre for Research on Energy and Clean Air (CREA) covering July and August put the volume of solar power that transmission networks were unable to take up at roughly 4.2% of total generation, pointing to gaps in the capacity of existing grid infrastructure to handle renewable output.

Those figures point to a tension at the heart of India's push toward 500 gigawatts of renewable capacity by 2030 — a goal roughly 196 GW beyond the 304 GW already installed — as analysts at CREA noted that even when output from renewable sources reached record levels, substantial portions of that electricity went unused due to constraints in grid infrastructure and day-to-day system operations.

Official data covering the April-to-June period put curtailed solar generation at around 14% of total potential grid output, a figure that sits alongside the country's standing as one of the world's three largest producers of solar energy. Government data shows that roughly 168 GW of installed solar capacity — representing close to one-third of total power generation — has outpaced what the country's transmission infrastructure was built to handle.

Curbs placed on lower-emission power sources came into effect at a point when July electricity consumption reached a peak of 270 GW and coal reserves held at power plants had fallen noticeably, the energy think tank reported. Fuel stockpiles at close to half of the nation's coal-fired power stations had dropped below a four-day supply threshold at the start of the month.

Non-fossil power sources crossed the halfway mark of the country's total installed generation base after India brought substantial new renewable capacity online throughout the past year. Output from solar sources climbed 39% against the same period a year prior, and the three-month window through September also saw non-hydro renewables collectively surpass 100 billion units of generation for the first time on record.

Fossil fuels tightened their hold on India's electricity mix over the quarter, with coal alone meeting roughly two-thirds of total demand even as renewable output reached new highs — a pattern driven by climbing consumption and a roughly 20% drop in hydropower generation attributed to the El Niño weather event, the report found.