Load shedding fears in summer: Why India’s grid managers are concerned

Thermal squeeze in non-solar hours

India has been adding renewable energy at a rapid pace — over 21 gigawatt (GW) of renewable capacity, excluding large hydro, was added between April and January of the ongoing fiscal, more than doubling year-on-year. Total capacity has touched 165 GW, and with large hydro, it is a little over 212 GW. In comparison, coal-based thermal capacity stands at 220 GW.

However, unlike thermal capacities, which can be ramped up and down as per requirements, renewable energy sources like solar and wind rely on specific atmospheric conditions to generate power. They produce electricity only when weather conditions permit — solar during the day, wind when speeds are sufficiently high.

During summers, solar generation typically peaks in the afternoon but drops off by evening, leaving a supply gap at a time when temperatures are high and households across north India switch on air conditioners.

Then, to meet high demand in non-solar hours, baseload capacities like thermal are ramped up. However, since India’s coal-based thermal capacity has barely grown, just 7 per cent from 205 GW in 2019-20, it is increasingly unavailable to bridge the shortfall in non-solar hours.

Until recently, grid operators had room to ramp up the plant load factor (PLF) of thermal capacities, including gas, as about 92 GW of thermal capacity was added between 2012 and 2017. Now, with thermal plants already running at high PLFs during non-solar hours, stepping up further has become more difficult.

Shortages expected this summer

India’s peak power demand has surged from 169 GW in 2018-19 to 250 GW in 2024-25, and is projected to touch 270 GW this summer. But with rising demand and increasing reliance on solar and wind, which have grown from 72 GW in 2019-2020 to over 150 GW in February, grid stability has become a growing concern.

In late February, an unseasonal cloud cover over northern India caused solar generation to plummet, triggering a sharp dip in grid frequency, which created a sudden scare for grid managers. Rapid demand-supply imbalances, especially in the absence of energy storage systems, can cause grid frequency deviations, which, if uncontrolled, may necessitate forced load shedding to prevent system instability.

This summer, India’s top grid operator is anticipating power shortages from April to October, with May and June flagged as “high-risk months”. According to the National Load Despatch Centre (NLDC), unmet electricity demand could reach 15-20 GW, particularly during non-solar hours.

“May 2025 is the most critical month, followed by other high-demand summer months. The data suggests that system vulnerabilities are heightened during these periods, likely due to peak demands and potential variability in renewable generation,” the NLDC said in a report released in January.

In the best-case scenario, the loss of load probability (LOLP) – a measure of the likelihood that electricity demand will exceed supply – is estimated at 19 per cent for May. In the median scenario, the LOLP rises sharply to 31 per cent, meaning there is nearly a one-in-three chance that supply will fall short. For June, the probability of a shortfall ranges from 4.7 per cent in the best-case scenario to 20.1 per cent in the median scenario.

“Shortages are more likely to occur during non-solar hours in May, June, July, and August 2025. It could also be inferred that meeting maximum demand during solar hours is not an issue, as solar generation significantly contributes to supply adequacy during these periods,” the report said.

Energy storage systems key

Recognising the grid stability challenges posed by intermittent renewables, the Central Electricity Authority (CEA) —  a state-owned planning body for the power sector — issued an urgent advisory on February 18, calling for energy storage systems to be co-located with solar projects. Battery energy storage systems (BESS) and pumped storage plants (PSP) can store surplus solar power during the day and release it when demand surges outside daylight hours.
While the country’s total renewable energy capacity has crossed 200 GW, the installed energy storage capacity till end-2024 was just under 5 GW (4.75 GW of PSP and 0.11 GW of BESS).

“The timely commissioning of BESS and PSP, as mentioned by CEA, is crucial to ensuring grid stability and managing peak demand efficiently. Any delays in their deployment could exacerbate energy shortages, particularly during high-demand months and non-solar hours. Ensuring these resources are available as planned will enhance system flexibility, support renewable integration, and mitigate reliability risks,” the NLDC report noted.

Over the years, BESS prices have come down significantly, making them financially viable for developers. Still, capacity addition in India has been slow.

In 2024, tenders to develop projects with 3.6 GW, or 8.1 GW-hour, of standalone BESS were floated by various agencies in India, according to Mercom. India needs 208.25 GWh of BESS by 2030, according to an estimate by the Council on Energy, Environment and Water (CEEW).

In the final quarter of the ongoing fiscal, the NLDC projected an addition of 4 GWh of BESS and 7.3 GWh of PSP in its January report. In 2025-26, it expects another 13 GWh of BESS and 8.9 GWh of PSP to come online.

The thermal fumble

In a measure to increase active generation capacity, the NLDC has suggested invoking emergency powers under Section 11 of the Electricity Act, 2003 to require imported coal-based plants to run at higher capacities.

“To mitigate supply shortages, directions under Section 11 of the Electricity Act for imported coal-based thermal stations should be considered. Given their higher generation costs, these stations are generally dispatched less frequently. However, during periods of system stress, their optimal utilisation can play a crucial role in meeting peak demand,” it added.

To manage intermittency, utilities are keeping aging thermal units on standby, but this comes at a high cost. “The concept of renewables achieving grid-parity is proving to be a farce. If the cost of standby thermal power is taken into account, renewable power is now almost twice its cost on paper,” an expert closely associated with the capacity addition plan told The Indian Express.

Added to that are the policy missteps over the past decade are now coming home to roost. The Union Power Ministry’s National Electricity Plan (2017-22) had effectively ruled out fresh thermal capacity additions beyond 2022, apart from the 50 GW of under-construction projects. The plan’s focus was almost entirely on scaling up renewables. Additionally, imported coal-based projects were actively discouraged, primarily in the wake of spiralling global coal prices.

In January, The Indian Express had reported that multiple under-construction thermal plants were facing delays due to theft and fire, slow civil works, and raw material shortages. Since the planning misstep of 2016-17, some corrective measures have been taken – a renewed push for nuclear generation in fleet mode, a belated drive to add large thermal capacities, importing coal to restart idle plants, and policy shifts such as the latest CEA directive mandating storage for all new solar projects.