Though solar farms have helped India avert daytime supply gaps, a shortage of coal-fired and hydropower capacity risks exposing millions to widespread outages at night.
While Indians looking to beat the heat will want steady power for their air-conditioners, nighttime outage risks threaten industries that operate around the clock.
India's power availability in "non-solar hours" this April is expected to be 1.7% lower than peak demand - a measure of the maximum electricity requirement over any given time, an internal note by the federal grid regulator reviewed by Reuters showed.
April nighttime peak demand is expected to hit 217 gigawatts (GW), up 6.4% on the highest nighttime levels recorded in April last year.
"The situation is a little stressed," Grid Controller of India Ltd (Grid-India) said in the note dated Feb. 3.
While Indians looking to beat the heat this summer will want steady power for their air-conditioners, nighttime outage risks threaten industries that operate around the clock, including auto, electronics, steel bar, and fertilizer manufacturing plants.
The electricity deficits this summer could be worse than expected, as Grid-India's shortage forecasts were made weeks before India's weather office predicted heat waves between March and May.
India's federal power secretary Alok Kumar downplayed concerns, saying the government had taken "all steps" to avoid power cuts.
After the Grid-India report, the government brought forward maintenance at some coal-fired power plants and secured extra gas-fired capacity to run to try to avert outages, another senior government official said.
Hydropower will be crucial not only to meet much of the remaining supply but also as a flexible generator, as coal-fired plants cannot be ramped up and down quickly to address variability in demand.
However, Grid-India has forecast peak hydro availability in April this year will be 18% below what it was a year earlier when output was boosted by favorable weather conditions.
The nighttime outage risks are in sharp contrast to daytime. Supply in daylight hours has been bolstered by nearly four-fold growth in solar capacity over the past five years, in line with Prime Minister Narendra Modi's Paris climate agreement pledge to curb carbon emissions.
As of last April, solar boosted renewables' contribution to as much as 18% of India's generation in the middle of the day.
The widening demand-supply fault lines highlight the need to expedite coal capacity additions to avert outages in the next few years.
Construction of as many as 26 coal-fired units with a capacity of 16.8 GW has been delayed by more than a year, data from the Central Electricity Authority shows, with some plants facing delays of more than 10 years.
Projects under construction are being stalled by local protests over environmental concerns, legal challenges overcompensation for land acquisition, and availability of labor and equipment, according to officials at power plants.
Hydro and nuclear power capacity additions face tougher obstacles, as they are hobbled by a lack of foreign investment and opposition from critics over safety and environmental issues, boding ill for power supply down the track.