India’s rapid expansion of solar power is creating a growing need for greater flexibility in conventional power generation. A committee under the Central Electricity Authority (CEA) has recommended using selected ageing coal-fired power units in a two-shift operating mode to help integrate up to 292 GW of solar capacity by 2030.
The committee has identified 151 coal-based generating units, each with a capacity of 210 MW or below and at least 35 years old, for potential two-shift operation. Together, these units have a combined capacity of around 34.5 GW.
Older Coal Plants Could Provide Flexible Support
Under the proposed model, selected thermal units could reduce generation or remain shut during peak solar-generation hours, generally between 9 am and 4 pm or 10 am and 5 pm. They could then restart during the evening as solar generation declines and electricity demand rises.
After considering availability and auxiliary consumption, the identified fleet could provide approximately 24.2 GW of flexible capacity to support the power system.
The approach is aimed at addressing the growing “duck curve” effect, where solar generation pushes net electricity demand down during the day before demand rises sharply in the evening.
Lower-Cost Alternative to Battery Storage
According to the committee, retrofitting these ageing thermal units for flexible operation could offer a relatively low-cost option for renewable-energy integration because much of their original capital investment has already been recovered.
The estimated capital expenditure for retrofitting the 151 units is around ₹30,200 crore. The committee estimates that the fleet could provide storage-equivalent support of roughly 27 GW, compared with an estimated ₹1.75 lakh crore investment for a comparable BESS capacity.
For a 210 MW thermal unit, the estimated renewable-integration cost through two-shift operation is around ₹1.46 per kWh, potentially increasing to ₹1.60 per kWh with higher capital expenditure.
Growing Solar Capacity Increases Grid Flexibility Needs
India’s expanding solar capacity is changing the country’s daily electricity-demand pattern. During periods of high solar generation, thermal plants may already be operating near their technical minimum levels, leaving less room to accommodate additional renewable power.
The CEA committee has therefore highlighted the need for deeper generation turndown, faster ramping and flexible thermal operation to maintain grid stability.
The report also points to instances of renewable-energy curtailment and grid-frequency challenges, underlining the need to create additional flexibility as solar capacity continues to rise.
The proposed two-shift operation of older coal plants is therefore being considered as a way to make greater use of existing thermal infrastructure while allowing more solar power to be absorbed into India’s electricity grid.
