India grapples with grid curtailment, biggest test yet on energy transition

Rising renewable energy capacity is straining India's grid, forcing curtailments and raising concerns over stability, storage gaps and the need for flexible thermal operations

With the rising share of renewable energy in India's energy basket, the key challenge for policy planners is to maintain grid stability and avoid supply curtailments. Solar and wind energy plants generate power intermittently, which causes disturbances in the power grid, requiring stronger baseload support from coal or nuclear power plants. This seemingly simple issue now occupies a central place in the long list of problems to tackle for a meaningful energy transition to renewables.

 

Central Electricity Authority (CEA) Chairman Ghanshyam Prasad last week highlighted the issue of India's power grid facing oscillations due to the variable nature of electricity generated by renewable energy (RE) projects. Grid oscillations occur due to fluctuations in transmission voltage and can significantly harm power-transmission equipment or cause massive blackouts.

 

India’s electricity system operates at 50 hertz and has long depended on large coal and hydro stations to provide inertia and voltage stability. But with rapid growth in renewable capacity, a larger share of generation now comes from inverters, which do not inherently supply the same inertia or short-circuit strength. Vikas Gaba, partner and national head (Power and Utilities), KPMG India, said: “This makes the grid more sensitive to sudden changes in renewable output, leading to sharper frequency variations and voltage oscillations, particularly in weaker grid pockets such as parts of Rajasthan and Gujarat.”

 

Addressing an industry gathering in New Delhi, Prasad said: "What we have started seeing is, because of the variability in solar and wind, there are oscillations that have started happening in the grid which is really dangerous. And we need to arrest them as quickly as possible. In one of the oscillations which I was reviewing two days back, I found that the oscillation was generated in Rajasthan and that was even felt in Kudankulam. So, you can imagine the impact because our entire grid is integrated. So, we need to be very very careful."

 

Two related issues further exacerbate this problem: the variability in power demand patterns, and the mismatch between the commissioning of generation capacity and transmission lines. Peak power demand grew at a compound annual growth rate (CAGR) of 6 per cent in the 10 years between 2014 and 2024. The growth rate fell to 2.7 per cent last financial year 2024-25. In the first nine months (April to December) of the current financial year, peak power demand dropped more than 2 per cent to 242,773 megawatt (MW), according to CEA data. Prasad said in his address that FY26 witnessed a very good monsoon, lowering demand below the targeted level. "There is no bottleneck in meeting the demand but unless demand growth happens, the absorption of renewables which we have already targeted is facing some issues," he said.

 

Two states in particular, Rajasthan and Gujarat, have witnessed grid curtailment recently due to the mismatch between capacity addition and Right of Way (RoW) issues. The capacity curtailment in Rajasthan has been brought down from around 9 Gigawatt (GW) recently to 3 GW at present. The commissioning of new transmission lines is expected to improve the situation in the coming months.

 

“Renewable power curtailment in the two states has eased following the commissioning of interstate transmission assets, including the 765 kV Khetri–Narela D/C line and strengthening of the Bhadla–Bikaner corridor,” said Gaba. Further relief is expected as projects such as the 765 kV Bhadla II–Sikar II D/C line, associated substations, and corridor upgrades are completed, he added.

 

As a solution, the CEA recently proposed a scheme to the power ministry to provide incentives for thermal power plants to adopt flexible load operations. "Whatever operational challenges exist and operational compensation is required must be done. So far, we are facing some challenges with respect to the state commissions who have not yet adopted the compensation principles adopted by the Central Electricity Regulatory Commission (CERC)," Prasad said, adding that the incentive scheme being discussed will address some of the concerns of thermal power plants nudging them to adopt a higher degree of flexibility in operations.

 

India has also finalised the Central Electricity Authority (Flexible Operation of Coal-based Thermal Power Generating Units) Regulations, 2023, which require coal units to lower minimum technical loads (MTL) and enhance ramping capability. “Demonstrations by some central generators indicate technical feasibility, though frequent cycling increases heat rate, wear and maintenance costs,” said Gaba, while also adding that scaling flexibility will also require physical and operational modifications at plants, alongside market-based compensation, revised PPAs, improved coal quality management and parallel deployment of storage and ancillary service markets.

 

GRID-India, which manages national electricity grid operations, recently told the CEA that it had to curtail as much as 23 GW of renewable energy between May and November, 2025, to maintain grid safety and stability because of rising RE generation.

 

Grid India has reported oscillations and line trippings at renewable pooling stations (Phasor Measurement Unit data), managed through curtailment and operational interventions, Gaba of KPMG said.

 

Energy think tank Ember estimates that compensation of Rs 5.75 trillion–Rs 6.99 trillion had to be paid for the curtailment of 2.3 terawatt hours (TWh)of solar generation between late May and December 2025. The total recorded curtailment is equivalent to nearly 18 per cent of the average monthly solar generation of  about 13 TWh, the report said.

 

The curtailment was required because a large part of India’s coal-based thermal fleet cannot operate below 55 per cent MTL, the lowest stable generation level at which a thermal unit can safely operate without shutting down.

 

As a long-term solution for the intermittency problem associated with RE plants, the government is working on building massive energy storage capacity in the country, including both Battery Energy Storage Systems and hydro Pumped Storage Projects (PSPs). According to a roadmap released by the CEA last month, India’s installed capacity of pumped storage projects is expected to exceed 100 GW by 2035-36 as the country steps up investments in long-duration energy storage to support the rapid expansion of renewable power.

 

The roadmap estimates that reaching this capacity will require average annual additions of about 9 GW and cumulative investment of around Rs 5.8 trillion, based on an average cost of roughly Rs 6 crore per MW. The projected capacity addition aligns with India’s energy transition targets, including the goal of achieving 500 GW of non-fossil fuel capacity by 2030. Besides balancing intermittent renewable energy output, pumped storage capacity is also expected to play a key role in grid stability by providing frequency regulation and voltage support.