BESS 101: Understanding the Battery Energy Storage Systems Powering India’s Future

To understand BESS, we first have to look at the flaw in renewable energy.

Governments worldwide are rushing to install solar panels and wind turbines. But these power sources have a fatal flaw: intermittency. The sun doesn’t shine at night, and the wind doesn't blow on command.

Often, solar panels generate the most electricity during the middle of the day when people are at work, and demand is low. But when everyone gets home at 7:00 PM and turns on their ACs, TVs, and appliances, demand spikes—just as the sun sets and solar generation drops to zero.

If you can’t store that midday solar power, it is completely wasted.

The answer to this problem — and one of the most interesting value chain opportunities to follow in the Indian energy sector right now — is BESS. Battery Energy Storage Systems. And two companies you may already know very well, Amara Raja Energy & Mobility and Exide Industries, are positioning themselves right at the heart of this revolution.

But before we get to the stocks, let's truly understand what BESS is, what it actually does, and why it matters so much.

Part 1: What Exactly Is BESS? 

Think about what a water tank does. You don't need your municipality to send you water at the exact second you turn on the tap. Instead, water is pumped into your tank during the night, sits there patiently, and flows out when you need it in the morning. Simple.

BESS is the exact same idea — but for electricity.

A Battery Energy Storage System is essentially a very, very large bank of batteries. Not the tiny AA cells in your TV remote. We're talking about rows and rows of large lithium-ion/lead acid battery packs — sometimes filling an entire warehouse, sometimes stacked inside massive shipping containers — all connected and hooked up to the electrical grid.

When the grid has more electricity than people are using (say, on a sunny afternoon when solar farms are running at full capacity), the BESS "drinks" that extra electricity and stores it inside the batteries.

When the grid is under pressure — when it's evening, when it's raining, when there's a spike in demand — the BESS "releases" all that stored electricity back into the grid, instantly, filling the gap.

That's it. That's BESS in a nutshell. A giant, sophisticated electricity sponge.

Part 2: But Why Now? Why Is BESS Such A Big Deal Today?

For decades, when engineers wanted to store electricity at a large scale, they built "pumped hydro" plants — massive dams where you pump water uphill when you have extra electricity and release it downhill through turbines when you need power. It works. But it requires rivers, the right terrain, and years of construction. You can't just build one anywhere.

The world needed a more flexible solution. 

The Renewable Energy Explosion

Governments around the world — including India — have made firm commitments to move away from coal and towards solar and wind power. India alone has a target of 500 GW of renewable energy capacity by 2030. These sources of energy are wonderful and clean, but they are fundamentally intermittent — they only produce power when the sun shines or the wind blows. Without a way to store that power, a purely renewable grid becomes impossible to manage. BESS is the missing piece of the puzzle.

According to BloombergNEF data, global annual energy storage additions are on a near-vertical growth curve — expected to surge from a handful of gigawatts in the early 2020s to nearly 200-300 gigawatts per year by 2035. The energy storage boom, the data shows, is now spreading well beyond China and the United States into India, Southeast Asia, and Africa. This is not a niche technology. This is becoming mainstream infrastructure. 

Even when you look at what’s driving the end use for Lithium, energy storage systems are already a growing theme and will continue to grow in the future.

Part 3: Where Are BESS Systems Actually Used? The Four Big Buckets

This is where it gets really interesting. Because BESS isn't just one thing used in one place. It's a platform technology with multiple applications. Our presentation identifies four distinct markets, each with its own customers and its own logic.

Bucket 1: Grid-Scale Storage (The Biggest One)

This is BESS in its most dramatic form. We're talking about installations that could be the size of a very large size — massive battery farms built right next to solar or wind power plants, or strategically placed around the electricity grid.

Who buys this? Large power generation companies — think Adani Green Energy, Tata Power, NTPC.

The problem it solves: Solar panels only make power at noon when the sun is out. But everyone goes home and turns on their air conditioners at 8 PM when it is dark. Without storage, the grid operator either has to keep a diesel or gas power plant running on standby (expensive and polluting) or risk blackouts.

A grid-scale BESS acts like a giant sponge. It soaks up the extra solar power at noon, holds onto it, and releases it onto the grid at night. Without these giant batteries, the dream of a 100% renewable energy grid is essentially impossible.

Bucket 2: Telecom Towers

This is a use case that most people completely overlook, but it is enormous in India.

Who buys this? The big telecom companies are Reliance Jio, Bharti Airtel, and Vodafone Idea.

The problem it solves: India has hundreds of thousands of mobile phone towers, many of them in rural areas where the power supply is unreliable, and power cuts can last for hours. If a tower loses power, the phone network crashes. Think about how many times you've needed your mobile signal urgently — and imagine if it went dead every time there was a power cut.

Historically, telecom companies solved this with loud, highly polluting diesel generators or with heavy lead-acid battery banks. These were expensive to run and maintain. Today, lithium-ion batteries are increasingly taking over this role. They charge much faster, they last roughly 5 times longer than lead-acid batteries, and they take up a fraction of the space in a crowded tower compound.

Bucket 3: Data Centres

This one might surprise you. But think about it for a second.

Who buys this? Technology and cloud computing companies — Amazon AWS, Google, Microsoft, and a growing number of Indian IT parks.

The problem it solves: A data centre houses tens of thousands of servers that are keeping the internet, cloud services, and AI applications running 24 hours a day. If the power drops for even a fraction of a second, millions of dollars of data processing can be lost or corrupted. These facilities need what's called an Uninterruptible Power Supply (UPS) — batteries that kick in the instant grid power fails, holding the fort until backup generators come online.

As artificial intelligence grows more powerful and requires ever-larger data centres, the demand for high-grade battery backup systems within these facilities will grow right alongside it. India is becoming a major hub for data centres, with massive new campuses being announced regularly. Each one is a customer for lithium-ion battery systems.

Bucket 4: Commercial & Residential Backup

This is the most relatable category. Think of this as the modern, high-tech successor to the trusty home inverter that millions of Indian families have used for decades.

Who buys this? Shopping malls, factories, individual homeowners — essentially anyone who needs reliable power.

The problem it solves: A modern lithium-ion home or commercial battery system does everything an old inverter did, but better — it's lighter, lasts longer, needs zero maintenance, and can be paired with rooftop solar panels. During the day, the solar panels charge the battery. At night or during a power cut, the battery runs your home. Factories and malls use large versions of these systems to run their heavy machinery during daytime solar hours, drastically cutting their electricity bills.

 

Part 4: But Why Lithium-Ion Specifically? Why Not The Old Lead-Acid Batteries?

This is such an important question. So why does BESS need to be lithium-ion?

The answer comes down to one simple concept: the difference between a sprinter and a marathon runner.

Think of a traditional lead-acid battery as a sprinter. It's heavy, relatively cheap, and fantastic at delivering a massive, short burst of power — exactly what you need to start a car engine. That single thunderclap of electricity is what it's designed for.

Now think of a lithium-ion battery as a marathon runner. It's incredibly lightweight, can pack a massive amount of energy into a small space (what scientists call "energy density"), and instead of one burst, can steadily release power for hours on end. That endurance is exactly what BESS requires.

When a grid-scale BESS needs to power an entire city for four hours after the sun goes down, you need a marathon runner. 

Part 5: The Amara Raja & Exide Connection 

So, we've established what BESS is and why lithium-ion is the right chemistry for it. Now let's connect the dots to the two companies at the centre of our analysis.

Both Amara Raja and Exide are, at their core, companies that make products that store electricity. They've been doing it for cars, motorcycles, telecom towers, and factories for decades. BESS is the same fundamental skill, just at a larger scale, with a more advanced chemistry.

But here’s where it gets really interesting. While both companies are pursuing the same macro opportunity — the rise of lithium-ion batteries and energy storage — they are approaching it in noticeably different ways. Understanding that difference is the whole point.

Amara Raja: Betting on the Full New Energy Ecosystem

The first thing to notice is the name. The company is no longer just “Amara Raja Batteries.” It rebranded to Amara Raja Energy & Mobility (since September 28, 2023). That is not a cosmetic change. It is a deliberate signal that the company sees itself as an energy business first, with batteries being just one part of a much larger story.

On the BESS front specifically, Amara Raja is the more explicitly focused of the two, although Exide also sees the opportunity but hasn’t announced any specific targets. Amara Raja has made grid-scale BESS a stated priority — targeting a domestic market that their own analysis projects could reach 30 GWh by FY31. To put that in context, 30 GWh is enough battery storage to power a city the size of Hyderabad for several hours on stored electricity alone. That is the scale of opportunity they are positioning for.

Beyond BESS, Amara Raja is building its own Gigafactory to manufacture lithium-ion cells domestically — the same cells that go into EVs, energy storage systems, and everything in between. They have also forayed into AC/DC fast EV chargers, essentially building out the charging infrastructure that an EV economy needs to function. Management has also been clear that the traditional lead-acid battery business is far from dead, expecting it to keep growing at around 10% in the medium term, driven by replacement and auto demand, as well as industrial UPS requirements.

Exide: The First Mover in Lithium-Ion Cell Manufacturing

Exide’s approach is a little different, and it carries a specific advantage that the market is watching closely. Exide is positioned to be the first company in India to commission a sizeable greenfield lithium-ion cell plant for merchant supply. “Merchant supply” simply means they will sell cells to whoever wants to buy them — EV manufacturers, energy storage companies, data centres, anyone.

This is a strategically powerful position to be in because it means Exide does not need to pick one winner in the EV or storage race. It supplies all of them.

On the solar and home energy side, Exide has launched Exide Sunday — a fully digital, user-friendly platform that provides complete rooftop solar solutions directly to homes and businesses, with the battery backup built in. They have also announced Solar Grid-Tie Inverters, which connect a rooftop solar system directly to the electricity grid — essentially letting homeowners sell excess solar power back rather than waste it. And then there is a product that Exide has, that Amara Raja does not: submarine batteries for the Indian Navy. This is a highly specialised defence-grade product. It is a quiet but meaningful product that speaks to the depth of Exide’s manufacturing capability.

The Risk Both of Them Face

For all the excitement, there is one big cloud hanging over both companies equally: OEM backward integration. In plain English — the car companies making their own batteries.

In the traditional petrol-car world, the battery was a tiny, cheap component. No car manufacturer in their right mind would bother making it themselves. But in an EV, the battery pack is the most expensive single part of the entire vehicle — sometimes 30 to 40% of the total cost. That changes the calculation completely. Ola Electric is already producing its own lithium-ion cells at its Gigafactory. Tata Motors has made its intention to enter battery manufacturing very clear. Ashok Leyland has broken ground on a battery pack manufacturing facility in Tamil Nadu. If the companies buying batteries start making their own, Amara Raja and Exide lose a large piece of their future EV revenue before it has even fully arrived.

This is exactly why BESS — grid-scale energy storage — is such an important piece of the puzzle for both companies. The power companies building solar farms, the data centres running AI workloads, the telecom towers keeping your signal alive during a power cut — none of them are ever going to make their own batteries. They will always be buyers. And that is the market Amara Raja and Exide are racing to serve, alongside the ever-existing EV revolution, each in its own way. The opportunity is such that on 22nd April 2026, Amara Raja announced that the 16 GWh Gigafactory greenfield expansion that they are doing has now shifted strategy to balance the capacity equally between mobility and Energy Storage Systems, as before the entire 16 GWh was earmarked for mobility. 

For a deeper look at the financials, the market share numbers, and the full story of both companies — watch our video on Amara Raja and Exide Industries.

Data Sources: Company investor presentations, BloombergNEF, Adamas Intelligence, Tijori Finance, ICICI Direct. All financial figures are sourced from publicly available company disclosures.