India curtails 8,133 GWh of solar power as grid struggles to absorb excess daytime supply

Curtailment — when grid operators ask renewable energy plants to reduce generation to maintain system stability — translates into a substantial loss of clean electricity at a time when India plans to expands renewable ⁠energy capacity to meet its clean energy targets of 500 GW by 2030 from the present 288 GW.

The curtailment occurred despite there being few instances of shortages during daytime peak hours, underlining the crucial role solar power plays in meeting daytime demand and the scale of surplus generation going unused.

The glut of daytime solar generation was also reflected in power markets. During this summer, the spot electricity prices in the country’s power exchanges saw sharp volatility. On several days, the spot price of electricity in the real-time market segment on the Indian Energy Exchange (IEX) — India’s biggest power trading bourse — crashed to near-zero levels during daytime in multiple time slots, only to surge to the regulatory ceiling of Rs 10 per unit (kWh) during night-time.

Curtailment due to grid concerns

While renewable energy sources, such as solar, enjoy “must-run” status in India, they can still be backed down on grounds of grid security and system safety. One such mechanism is Emergency TRAS (Tertiary Reserve Ancillary Services), under which the National Load Dispatch Centre (NLDC) can direct inter-state transmission system (ISTS)-connected renewable energy projects to reduce generation during system-wide emergency conditions to maintain grid stability. It acts as the third layer of grid control after primary and secondary reserve responses, and is triggered when additional intervention is required to prevent instability.

In April, the curtailment under Emergency TRAS averaged 15.76 GWh per day, this newspaper had earlier reported, analysing data from Grid India. On April 5 alone, solar curtailment under the mechanism had touched 80.5 GWh — enough electricity to meet the daily needs of hilly states of Uttarakhand and Himachal Pradesh. Overall, curtailment in April was about 73.5% higher than the combined curtailment recorded during January to March, highlighting the growing stress on the grid amid rising renewable energy penetration.

Meanwhile, the sluggish pace of transmission infrastructure development has emerged as another major driver of renewable energy curtailment. According to the industry executives, the issue largely stems from a mismatch between the rapid pace of renewable energy deployment and the much longer timelines required for transmission planning, approvals, and construction.