India’s power transmission constraints could persist for years: Aurora Energy Research
- September 4, 2026
Aurora Energy Research, a global provider of energy market analytics, recently launch its “India Grid Service,” a first-of-its-kind subscription service that helps the power industry forecast renewable energy (RE) curtailment risk and assess grid connectivity across India. In this backdrop, tndindia.com caught up with Debabrat Ghosh, Country Head – India, Aurora Energy Research, to understand the technical intricacies of RE curtailment, its impact on the power value chain, and how “India Grid Service” can empower RE stakeholders as the nation gears up to meet the 900-GW non-fossil capacity target by FY32. An interview by Venugopal Pillai.
What is renewable energy curtailment in simple terms?
Curtailment happens when a solar or wind farm is technically able to generate and export electricity, but the grid operator instructs it to reduce or stop that output. The power that could have been produced is simply not used.
This is different from a plant being offline for maintenance, or short of wind or sun. During curtailment the asset is ready and able to produce, but the system will not accept the electricity: either the wires connecting it to the grid are not yet available at the capacity required, or there is more renewable power on the system at that moment than the grid can absorb.
How has RE curtailment worsened in India, and what are the primary reasons?
The increase has been sharp. Monthly renewable curtailment in India rose from 0.07TWh in January 2025 to 2.68TWh in May 2026, and the primary driver is a mismatch in build speed. Over 47GW of solar and 5.6GW of wind were added between May 2025 and May 2026 alone, and that growth has far outpaced transmission buildout.
The transmission network has grown at roughly 3 per cent a year since 2020, against 6.4 per cent for generation capacity. Network intensity has fallen to around 950 ckm per GW in 2025, from roughly 1,500 in earlier years.
This shows up in two ways. First, some assets are commissioned before their dedicated transmission line is ready, leaving them on non-firm grid access and exposed to temporary general network access (T-GNA) curtailment until that line is complete. Second, in renewable-rich states, combined solar and wind output can outstrip what the grid can absorb, driving high grid frequency events once thermal plants are already at their technical minimum and forcing the operator to curtail generation (oversupply curtailment).
Which stakeholders in the power value chain are most affected? Does it impact transmission service providers as well?
Developers carry the most direct and immediate impact, since curtailed generation is lost revenue, particularly where that loss is entirely uncompensated.
Lenders are affected one step removed: curtailment risk translates into weaker debt service coverage and less predictable cash flows than a standard PPA-linked financing model assumes.
Offtakers may be exposed as well, since curtailment upstream affects whether contracted renewable volumes are actually delivered. That shortfall has to be covered from the market, and which party absorbs the cost depends on how the individual contract allocates it.
Transmission service providers are also affected, though differently to generators. Their exposure is regulatory and legal rather than a loss of revenue: developers have filed compensation claims against transmission utilities for losses tied to delayed evacuation infrastructure, and regulators have admitted these petitions for hearing.
This is a new development, and it signals that transmission providers can no longer treat delivery timelines as a purely internal planning matter.
“Beyond the subscription itself, the grid model we have built for India Grid Service now supports bespoke work for clients who need any question answered at asset level rather than at market level.”
Please elaborate on the scope of Aurora’s India Grid Service. Who would benefit most?
The service has three core components, built on a single model of the Rajasthan grid, and it rolls out in waves across India’s renewable-rich states from there, reaching more than 80 per cent of the development pipeline within a year of launch.
- A databook tracker for when grid connection will actually be ready
- It covers grid connection applications across substations and transmission lines in Rajasthan.
- It shows how far each connection has progressed, including approvals pending for land, environment and forest clearance.
- It gives Aurora’s own estimate of the likely completion date, built from on-the-ground progress rather than the announced date.
- It is maintained as a live tracker and refreshed through the year as projects move through clearance and construction.
- A forecast of how much power is expected to be curtailed, and when
- It forecasts curtailment for solar and wind projects over the coming years.
- It covers T-GNA and oversupply curtailment separately: projects whose grid connection is not yet ready, and projects switched off because there is too much renewable power on the system at once.
- It gives an annual estimate of power lost to curtailment at each substation.
- Three scenarios are provided — a central case, a more cautious case and a more optimistic case — depending on how quickly infrastructure and storage are built out.
- It is refreshed as the pipeline and the transmission plan change, so the view moves with the market rather than fixing at a point in time.
- A tool to check how much room is left on the grid at any given site
- It covers substations across Rajasthan.
- It shows how much capacity is genuinely available at each site for a new project without running into curtailment.
- It also shows the worst-case exposure if that site becomes crowded with other projects competing for the same grid capacity.
- It covers solar and onshore wind projects across the sizes and timeframes most relevant to developers.
- Users can enter their own project details — capacity, technology, location and timing — for a tailored result.
- Subscribers can also put questions directly to the analysts who build and maintain the model, rather than working only from the published outputs.
- It is kept current alongside the forecast.
Beyond the subscription itself, the grid model we have built for this service now supports bespoke work for clients who need any question answered at asset level rather than at market level.
Developers and lenders benefit directly, since they are the parties whose revenue and debt service are exposed when an asset is curtailed, and they are the ones making the siting, sizing and financing decisions that a curtailment view changes.
Offtakers and transmission planners use it differently, to understand where contracted delivery is most at risk and where the network is tightest. On a bespoke basis we can address how much headroom is genuinely available at the substations their projects connect to, which locations are most likely to deliver contracted volumes reliably, and how siting decisions on new projects affect exposure over the life of the asset.
Across all of these, subscribers can put questions directly to the analysts who build and maintain the model, rather than working only from the published outputs.
Can we presume that RE curtailment is essentially because RE generation assets are being built faster than their evacuation systems?
That is broadly correct, but it is not the only reason. The core issue on the grid is a timing mismatch: a solar project can be built and commissioned in 12 to 18 months, while a new transmission line typically takes several years once land acquisition, right-of-way negotiation and forest clearances are accounted for, so generation arrives well before its dedicated evacuation infrastructure. Such capacity is given non-firm connectivity until the network catches up, which leaves the asset exposed to curtailment.
The other form is real-time oversupply curtailment, which occurs even on assets that already have full transmission access. It is initiated when renewable generation exceeds what the system can absorb with thermal plants already at their technical floor, regardless of whether the wires exist.
Evacuation availability is therefore one major driver of curtailment, but a second is tied to the shape and timing of demand and renewable generation.
“India’s experience is not unique. The same pattern appears in most markets adding renewables quickly.”
What is the general situation with RE curtailment in RE-rich nations worldwide? Is Aurora providing similar services elsewhere?
India’s experience is not unique. The same pattern appears in most markets adding renewables quickly, and we track it closely across several other markets in our regular publications.
In California, CAISO curtailed 3.4TWh of utility-scale wind and solar output in 2024. April 2026 was the highest month on record, with 1,300GWh of solar curtailed, or 21 per cent of solar generation that month.
In Germany, roughly 8TWh of wind and solar generation was curtailed in 2025, close to 3.4 per cent of the total. Our quarterly German Grid Curtailment Forecast shows redispatch volumes rising steeply to a peak of roughly 30TWh in the early 2030s, with congestion concentrated in the north of the country, where onshore and offshore wind generation is heaviest.
Spain and Japan are seeing the same effect, with renewable growth outpacing transmission expansion. We have been building grid and curtailment modelling capability since around 2020, starting in Australia, and have since extended it to more than ten power markets, including the United States, the United Kingdom, Spain, Japan, South Korea and the Philippines. The India Grid Service applies that same underlying capabilities, adapted to India’s grid rules and regulatory framework.
“Creation of transmission infrastructure can be accelerated to some extent, but the structural bottleneck is unlikely to disappear quickly.”
Given challenges like right-of-way and forest clearances, can transmission infrastructure creation be accelerated?
It can be accelerated to some extent, but the structural bottleneck is unlikely to disappear quickly, because it spans multiple agencies and jurisdictions that policy intent alone cannot compress.
That said, several levers are already in use and could be pushed further. Running land, right-of-way and forest clearance processes in parallel rather than sequentially can meaningfully shorten the critical path, and we have seen this attempted on recent projects with mixed success.
Undergrounding lines through the most litigation-prone or ecologically sensitive stretches, as has happened around the protected Great Indian Bustard zones, removes a recurring source of delay, though it adds cost.
Acquiring land ahead of formal connectivity applications, rather than starting the process only once a project is confirmed, would also help, since land and right-of-way disputes are consistently the largest single driver of delay.
What we caution against is assuming that announced acceleration measures will deliver commissioning on schedule. Our approach is to build commissioning timelines from on-the-ground construction progress, such as tower erection and line stringing, rather than from announced targets; the gap between the two has been consistently large.
Can battery energy storage, particularly long-duration storage, help address RE curtailment?
Yes, though different types of storage address different parts of the problem. Short-duration batteries, co-located with solar, allow curtailed midday output to be captured and discharged later rather than lost entirely.
In our own analysis of a solar-plus-battery asset, free charging from otherwise-curtailed solar delivers an IRR uplift of 1.5–1.7p.p. against charging from the grid.
Long-duration storage matters for a different reason: short-duration batteries shift a few hours of surplus, but not the multi-hour, system-wide oversupply that grows as renewable penetration rises. That is why CEA’s resource adequacy studies point to around six hours of long-duration storage beyond 2030.
“The same core problem — generation outpacing transmission and flexibility — is expected to shape India’s power sector for the rest of this decade at least.”
How do you see the road ahead for India Grid Service, and what is the plan to progressively cover other RE-rich states?
India’s transmission challenge is being planned against a 500-GW non-fossil target by 2030, extended by CEA’s more recent plan to over 900-GW by 2035-36. Either figure implies constraints that could persist for years, which is why we offer this as an ongoing subscription on a biannual forecast cadence rather than a one-off report.
The rollout begins in Rajasthan in August 2026 and expands in waves: Gujarat and Maharashtra next, then Karnataka and Andhra Pradesh, then Telangana and Tamil Nadu, with the goal of covering more than 80 per cent of India’s renewable development pipeline within a year of launch.
We are starting with the states where curtailment is worst and renewable capacity is growing fastest, and we expect the same core problem — generation outpacing transmission and flexibility — to shape India’s power sector for the rest of this decade at least.