Grid curtailment
Also called: Curtailment · Topic: Infrastructure: Transport, Communications and Energy · NCERT: Beyond NCERT
Meaning
Grid curtailment happens when the grid operator orders a solar or wind plant to produce less power, or to stop, even though the sun is shining or the wind is blowing. The grid operator is the agency that balances power supply and demand on the grid. There are three common reasons:
- Transmission lines (the high-voltage wires that carry power from plants to cities) are full or not built yet.
- Demand at that hour is too low.
- Coal plants cannot cut their own output fast enough to make room.
The power that could have been made is simply lost. So curtailment wastes clean energy and cuts the plant owner's income. It also shows that installed capacity (GW) is not the same as power actually delivered (GWh).
Example
Around noon, many solar parks in western India hit their highest output. The lines out of the region are already full, and nearby coal plants cannot ramp down quickly. The operator tells some solar parks to cut output. For those hours, the sunlight produces no usable power. This is why storage, such as batteries and pumped hydro, and new transmission lines matter as much as new solar panels.
Don't confuse with
- Load shedding: power supply to consumers is cut because demand is higher than supply. Curtailment is the opposite: generators are cut back because there is more supply than the grid can take.
- Low plant load factor (PLF): PLF is a plant's actual output as a share of its maximum possible output. It can be low for any reason, such as cloudy weather or breakdowns. Curtailment is one specific reason: the plant could generate, but the grid tells it not to.
Recent developments
- 2025: Up to 8 GW of renewable capacity in Rajasthan faced curtailment, mostly because transmission lines and substations (such as Neemrana-II and Bikaner-III) were not ready, with possible losses of nearly ₹700 crore. This is the clearest recent Indian case of the cause the page calls "lines are full or not built yet," and it shows how large the gap between GW and GWh can get.
- 2025: Developers asked the Centre for a relief package of up to ₹3,000 crore to cover these grid delays. This shows that curtailment is not only wasted clean energy but also a real financial hit to plant owners, which can discourage new investment.
- 19 December 2025: The Supreme Court's Great Indian Bustard (GIB) judgment ordered 80 km of 33 kV lines in Rajasthan to be undergrounded (laid under the ground). It also ordered other lines to be rerouted or fitted with bird diverters within two years. These slower, costlier lines may lengthen transmission delays, which is the main driver of curtailment in Rajasthan.
- October 2026: Green Energy Corridor-III, a new scheme for state-level renewable transmission, was reported with ₹54,082 crore of central assistance. It is the main policy tool for cutting curtailment, because it builds the lines that carry renewable power out of states like Rajasthan.