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Grid, transmission and storage
India has built renewable capacity faster than the wires to carry it and the storage to hold it, so solar plants are being told to cut output in the middle of the day. The binding constraint is no longer how much can be generated but whether the grid can move it, absorb it and keep it steady. The money is now following the wires and the batteries rather than the panels.
UPSC has asked
- Prelims 2025: PM Surya Ghar Muft Bijli Yojana and rooftop solar
Why a renewable heavy grid needs firming
- Solar and wind generate when the weather allows rather than when demand asks, so their output has to be firmed by something that can be called on.
- Indian demand peaks after sunset while solar generates at midday, leaving too little daytime load to absorb what the panels make.
- Storage does the firming by holding the midday surplus until the evening peak, but it still costs more than coal or solar power.
- Where neither the wires nor the load can take the power, the cheaper answer is curtailment, and the loss falls on the generator.
Transmission is the bottleneck, not generation
- Transmission is congested, so power from renewable rich States cannot reach the buyers who want it.
- The Green Energy Corridor is the programme that builds the lines evacuating that power, in intra-State and inter-State phases.
- Right of way disputes and forest clearances have delayed the earlier phases, as have restrictions on overhead lines meant to protect the Great Indian Bustard.
- Capacity connected on temporary network access is curtailed first, so those projects lose the most.
Why a grid of inverters is weaker
- Solar and wind are inverter based resources, so a grid leaning on them has less rotating inertia to hold its frequency steady.
- That shows up as a lower short circuit ratio, a measure of grid strength, leaving voltage and frequency less stable.
Where India has got to
- Non fossil capacity has crossed 300 GW, and renewables reached a record 20 per cent of generation in July 2026.
- About 283 GW of renewables are installed against a target of 500 GW by 2030.
- The 50 per cent non fossil capacity target was met five years early, and the goal now is 60 per cent by 2035.
The three ways out
- Move demand into solar hours through industrial electrification, workplace charging and time of day tariffs.
- Pair rooftop solar with home batteries so a household stores its own midday surplus.
- Treat curtailment as a paid grid service rather than an uncompensated loss to the generator.
What has happened
20 Aug 2026
A rating agency put numbers to the solar output being cut for want of transmission.
- Projects on temporary network access are losing 30 to 50 per cent of their output.
- 8,133 million units of solar generation were curtailed in the first half of 2026, with peaks of 8.6 GW in western India and 5.6 GW in the north.
- New renewable auctions have slowed sharply, and 40 to 45 GW of awarded capacity has no signed power purchase agreements.
The Hindu, 20 Aug 2026: Transmission bottlenecks force curtailment of renewable power (opens in a new tab) · The Indian Express, 25 Aug 2026: How to make a solar-heavy grid stable and affordable (opens in a new tab)
12 Aug 2026
Public money behind storage was set out as two pots for batteries and one manufacturing target.
- Viability gap funding covers 13.8 GWh of battery storage, with a further 30 GWh under the Power System Development Fund.
- The production linked incentive scheme for Advanced Chemistry Cells targets 50 GWh of cell making capacity in India.
PIB, 12 Aug 2026: Green hydrogen in refineries, battery storage and EV schemes (opens in a new tab)
11 Aug 2026
The third phase of the intra-State Green Energy Corridor went to the Union Cabinet for approval.
- The expected outlay is over ₹50,000 crore.
- It would evacuate about 135 GW of renewable power from renewable rich States.