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High Renewable Injection Triggers Grid Frequency Imbalance; CERC Flags Operational Challenges

India's power grid is grappling with repeated frequency fluctuations due to the rising share of renewable energy, particularly solar, in the electricity mix. In the latter half of FY 2024-25, grid frequency exceeded the permissible 49.90-50.05 Hz band on 39 days, remaining above limits for over 20% of the time on those days. The issue stems largely from excessive renewable power injection, especially during low-demand solar hours, and the limited flexibility of thermal plants to ramp down without affecting their operational integrity.

Grid-India reported that instantaneous renewable energy penetration has reached ~37%, expected to cross 40% by early 2026. These levels are straining the grid’s balancing mechanisms, particularly during the evening ramp-up period when solar output drops and demand surges. On multiple occasions, including Sundays in August 2024, frequency spikes were linked to over-injection of solar and wind, with insufficient ramping support from hydropower and pumped storage plants.

The Central Electricity Regulatory Commission (CERC) has responded by directing national and state load despatch centers to enforce stricter compliance with scheduled generation and drawal. NTPC raised concerns about the lack of corresponding obligations on beneficiaries to maintain minimum thermal schedules, leading to infeasible generation patterns and over-injection during off-peak periods—at times reaching 2,200 MW.

To address this, CERC has recommended exploring two-shift operations for thermal plants, enabling them to operate during high-demand hours while avoiding over-generation during solar-dominated periods. The situation underscores the pressing need for enhanced grid flexibility, scheduling reforms, and ancillary services to support India's fast-expanding renewable energy capacity.