Inverter batteries — low-voltage lead-acid systems, capable of charging up from a wall socket and powering a few lamps, some fans and perhaps a television for a few hours when the power drops — are a product of decades of unstable grid power. They’re a quiet, clean replacement to the diesel generators that were ubiquitous in earlier decades. Now, more powerful lithium-ion units are promising yet another revolution.
“India has been into distributed energy far longer than California,” said Preeti Bajaj, executive vice president of home solutions at Schneider Electric SE, a French power-equipment company whose Luminous brand has a dominant position in the market.
This storage fleet is almost invisible. Annual installations of Tesla Inc. Powerwall-style lithium-ion power packs are tracked and forecasted by multiple analysts, but inverter batteries are routinely ignored. Their scale is likely to be substantial, though. Luminous has 100 million customers across India. With a typical system holding one or two kilowatt-hours and plenty of other players in the market, that suggests such low-voltage equipment could be holding more than 100,000 megawatt-hours of charge, comparable to some of the largest lithium-ion fleets.
Most inverter systems still look distinctly lo-fi, with lead-acid batteries sold separately, connected to inverter units with bundles of wire, and needing to be topped up periodically with water.
That’s changing, however. Lithium-ion cells used to be far more expensive than lead-acid ones, but up-front prices are increasingly converging. Lifetime costs are already far lower, because lead-acid tends to degrade rapidly. The newer packs are also smaller and lighter and don’t contain easily-spilled acids, making them a better fit for a crowded home.
Rising electrification and energy efficiency is allowing them to power more devices. For around 30,000 rupees ($313), you can now buy a lead-acid system that will allow you to run an induction cooktop — a handy upgrade in a country facing shortages of cooking gas after the closure of the Strait of Hormuz.Batteries that will power an air-conditioner all night are still out of reach of typical urban households, but the gap is growing narrower by the year — especially as the spread of consumer finance makes it possible to pay for a purchase via monthly installments, rather than a one-time lump sum.
The benefits could stretch well beyond household convenience. As in the 1980s, India’s grid is struggling to handle the strain. Rising temperatures and incomes are sharply increasing the number of AC units pumping out cool air and sucking in electrons just as the sun goes down and solar panels switch off.
The trick is to transfer the looming surplus of midday solar power into the deficit hours of the evening. Vast quantities of electricity are already being thrown away because the grid can’t handle it when it’s available. Current government plans call for increasing the capacity of large-scale battery storage from 798 MWh now to 208,000 MWh in 2030, equivalent to the power of 3.5 million electric cars.
Small-scale plants could make a real difference. Add a typical battery to each of the 10 million home solar systems that are being installed by 2027 under a subsidy program, and you’ll have an extra 50,000 MWh. Even small inverter-based systems, if widely distributed among more than 100 million urban households, could store another 100,000 MWh or so. Then count the cells in growing fleets of electric bikes, cars, and rickshaws, and India already has many of the tools it will need to even out fluctuations in the grid.
What’s still lacking is an iPhone moment for home batteries: A killer device that combines the keen price sought by consumers with the simplicity that households in developed markets expect. It may emerge sooner than we think. Most Indian bill-payers will move within the next few years to smart meters. That will put a hard monetary value on the benefits of charging your home battery during the midday solar peak.
Indian households have depended on home back-up for decades because the grid was too rickety to rely on. That same spirit of self-reliance may help leapfrog wealthier nations on the road to electrification.
(This is an opinion piece by the author)