India curtails more solar power as grid grapples with oversupply

The data points to a deepening mismatch between supply and demand when solar generation floods the grid during the day time

India’s power grid is struggling to absorb a surge in solar power installations, leading to more curtailment that threatens the build-out of renewables and underscores the need for energy storage.

The curtailment rate for solar generation in October rose to about 12%, the highest since May when Grid Controller of India Ltd. started publishing the data. On some days, about 40% of solar power output was denied access to the national network. Curtailments measure how much electricity was generated without finding its way to customers.

The data points to a deepening mismatch between supply and demand when solar generation floods the grid during the day time. Coal power plants can’t reduce output fast enough to make room for surging solar output, and the fossil fuel must be kept in operation as it’s needed to meet demand after the sun sets.

The month also saw rare curtailments of wind power, the data showed. This highlights the need to integrate intermittent renewable energy sources with storage, like grid-scale batteries, so that excess electricity can be dispatched in the evening.

India has about 44-gigawatts worth of green projects that are struggling to find state utilities to buy their electricity. The government is considering canceling projects where prospects of an offtake deal looks minimal, threatening a goal of doubling clean power capacity to 500 gigawatts by the end of the decade.