India loses 2.1TWh of renewables as coal hits flexibility limit

This is equivalent to about INR629 crore of foregone electricity.

India is curtailing increasing volumes of renewable electricity because coal plants cannot reduce output below technical limits, according to an Ember report.

In a 17 June report, Ember said around 2.1 terawatt-hours of renewable energy were curtailed in the financial year 2025–2026 to maintain coal stability, equivalent to about INR629 crore of foregone electricity.

Solar and wind reached up to 41% of generation at midday in March 2026, pushing coal output down to about 54% during peak hours.

Coal fell below its technical minimum in more than half of midday dispatch intervals in April 2026, whilst renewable curtailment rose to 37% of down-regulation, up from near zero a year earlier.

At midday, up to 6% of solar and wind generation was curtailed, not due to congestion or weak demand, but because coal could not go lower, Ember said.

“Coal, which still provides almost all the grid’s flexibility … is being cycled from near-full output at night to its lowest point at midday every single day,” the report said.

It added that once coal reaches its minimum technical load of about 55%, “it has no further room to provide downward reserves,” and renewable generation must be curtailed to keep coal physically operable.

The constraint is structural and will worsen as solar capacity expands, with the think tank adding that “the constraint is structural, it worsens with every new solar panel added.”

The system requires around 10 gigawatt-hours of battery storage to absorb surplus midday generation and prevent curtailment.

It said storage would allow coal plants to remain above minimum operating levels whilst balancing excess solar output.

“Storage can unlock the next phase of renewable energy growth,” it said, adding that without additional flexibility, curtailment will rise as solar generation increases.