Are We Buying the Right Batteries for the Grid?

India has finally discovered electricity storage—and is now in danger of discovering it the wrong way.

Battery Energy Storage Systems (BESS) have become the new policy obsession. Tenders are flying, tariffs are being benchmarked to the last rupee, and headlines celebrate ever-falling ₹/MW-month numbers. Storage is being positioned as the silver bullet that will absorb solar surplus, firm renewables, eliminate curtailment, replace coal peaking, and guarantee reliability.

Yet beneath the excitement lies a deeper problem: India is procuring storage as a generic solution, not as a response to clearly diagnosed system needs. We are buying batteries first and asking questions later.

The result is a growing mismatch between what the grid actually lacks and what current storage deployments can realistically provide.

1. Storage Is Not One Product—But India Treats It as One

The first conceptual error is treating “storage” as a single, interchangeable resource. In reality, storage solves different problems, each operating on a different time scale.

             System Problem                    Time Scale                 What is needed

1.      Solar ramping                            Minutes-hours          Fast, Short-duration flexibility

2.      Evening Peak                              2-4 hours                      Peaking capacity

3.      Multi-day deficits                    24-72 hours                Long Duration Energy Storage

4.      Seasonal mismatch              Weeks-Months         Energy shifting, not batteries

5.      Resource Adequacy              Rare events                 Firm Capacity, not cycles

India’s current procurement overwhelmingly targets 2–4-hour lithium-ion batteries, as if all shortages occur neatly between sunset and dinner. They don’t.

2. The Solar Duck Curve Fallacy

The dominant justification for BESS continues to be the solar “duck curve”: low net demand in the afternoon followed by a steep evening ramp. While this framing is directionally correct, the scale of the Indian ramping challenge is now materially larger than what is typically presented.

India’s storage pipeline has exploded on paper—over 68 GWh awarded or tendered by November 2025, with another 10–15 GWh expected in FY26—yet operational capacity remains barely 500–550 MWh. This gap matters because the duck curve is no longer a marginal problem that can be addressed with a handful of pilot batteries; it is becoming a system-scale ramping challenge.

Recent system studies significantly revise the numbers. Greening the Grid / USAID analyses (2024–25) indicate evening net-load ramps of about 90–95 GW under high-RE scenarios. Looking ahead to 2030–2032, projections suggest maximum ramp rates of 110–160 GW per hour, driven by deeper solar penetration and continued growth in evening demand.

Take a more realistic high-RE evening ramp:

• Net-load increase: ~92 GW over roughly 3 hours

• Required BESS discharge power to fully smooth the ramp: ~90 GW

• Required energy:

  • 92 GW × 3 h ≈ 276 GWh

Even smoothing just one hour of extreme future ramps would require:

• 110–160 GW of instantaneous discharge power

• 110–160 GWh of energy per hour

At this point, power capability, not energy volume, becomes the dominant constraint.

Now compare this with the National Electricity Plan (NEP) 2031–32 storage projections:

• Battery ESS (BESS): 47 GW / 236 GWh

• Total ESS including pumped storage: ~74 GW / 411 GWh

Energy-wise, the numbers appear large. For a 92-GW ramp requiring ~276 GWh, total ESS energy including PSP (411 GWh) could, on paper, cover the requirement once. But the power requirement already exceeds available BESS capacity, and even total ESS power (74 GW) falls short of the observed ~90 GW ramp, let alone projected 110–160 GW/hour ramps.

More importantly, system reality intervenes:

• Storage is not fully deployable simultaneously in the 5–8 pm window

• Portions are charging, geographically constrained, or reserved for frequency control and contingencies

• A significant share is contracted for renewable firming, not national ramp management

• Evening peaks often persist for 4–5 hours, making full early discharge operationally unsafe

In practice, only a fraction of NEP-level ESS can be relied upon for a single national ramp event. Even if 40–50 GW of ESS contributes during the critical window, a large residual ramp remains, which must be met by hydro, gas, coal at part-load, imports, and operating reserves.

Bottom line:

• NEP storage can meaningfully reduce evening ramps

• It cannot eliminate them, even once, and certainly not repeatedly

• As ramp magnitudes rise toward 90–150 GW, storage becomes a supporting flexibility resource, not a substitute for firm, dispatchable capacity

So even with 47 GW / 236 GWh of BESS and 74 GW / 411 GWh of total ESS, India will continue to face a substantial residual ramp gap unless firm and flexible capacity is planned explicitly alongside storage.

3. The Capacity Illusion: MW Is Not Reliability

Most Indian BESS tenders are structured and advertised in MW terms. This creates a dangerous illusion that storage equals capacity.

Let’s examine capacity contribution properly.

Example: Capacity credit of 4-hour BESS

Assume:

1 GW / 4 GWh battery

Peak shortage window: 6 pm–10 pm (4 hours)

No recharge possible during peak

Best case:

Battery discharges fully once

Capacity contribution = 1 GW

But system planners care about reliability across events, not a single day.

Now consider:

Two consecutive high-demand days

Cloudy afternoons (limited solar recharge)

On Day 2:

Battery may start peak period at 50–60% SOC

Effective capacity = 0.5–0.6 GW

This is why globally:

4-hour batteries receive 40–70% capacity credit, not 100%

Capacity value declines rapidly as penetration increases

Yet Indian planning documents often implicitly treat BESS as firm capacity, inflating adequacy and deferring harder decisions on thermal, hydro, or demand response.

4. Storage Is Being Paid for Energy It Cannot Deliver

A key structural issue lies in how BESS is being paid, not just how much.

Most recent SECI tenders (without VGF) clear around:

• ₹1.8 lakh per MW per month

• Payment is almost entirely a fixed capacity charge, with weak linkage to actual dispatch or system outcomes.

Let’s translate this into delivered-energy economics.

Example: Typical SECI BESS (current bids)

Assume:

• Configuration: 1 MW / 2 MWh (2-hour BESS)

• Capacity charge: ₹1.8 lakh / MW-month

Annual fixed payment

• ₹1.8 lakh × 12 = ₹21.6 lakh per MW-year

Realistic utilisation (system reality, not brochure math)

Assume:

• Effective discharge days: ~200 days/year

• Average discharge duration: 2.5 hours
  (some days 2 hours, some partial, rarely full every day)

Annual energy delivered

• 1 MW × 2.5 h × 200
  = 500 MWh per year

Implied cost of delivered energy (capacity charge only)

• ₹21.6 lakh ÷ 500 MWh
  = ₹4.3 per kWh

This is before adding:

• Round-trip losses (~10%)

• Battery degradation

• Charging power cost (solar Avg. ₹ 2.5/KWh or DAM)

• Opportunity cost of using storage for reserves or congestion

After accounting for these, the effective delivered cost typically moves to:
➡ ₹7-8 per kWh

What this really means

• The system is not paying for cheap energy

• It is paying for standby availability

• Energy delivery is incidental, not guaranteed

This is not inherently wrong if:

• The availability coincides with genuine reliability risk

• Storage is called only when alternatives are costlier or unavailable

But today:

• Storage is contracted broadly

• Dispatched thinly

• And evaluated as if it were an energy resource

Bottom Line

We are paying BESS primarily for being there, not for what it actually delivers.
At current SECI bid levels, 2-hour storage is a flexibility insurance product, not an energy solution. Treating it as a substitute for firm or peaking capacity is an economic and system-design mistake.

5. The Wrong Duration Problem

India’s dominant risk is not intra-day balancing alone. It is multi-day and weather-correlated stress.

Examples:

Heatwaves with low wind and dusty skies

Monsoon breaks affecting hydro and solar simultaneously

High evening demand across regions at once

Short-duration batteries fail here.

Example: Two-day stress event

Assume:

Evening peak deficit: 8 GW

Duration: 4 hours

Event length: 2 consecutive days

Energy required:

8 GW × 4 h × 2 days = 64 GWh

A 4-hour BESS fleet can only discharge once per day if recharge is constrained. Without surplus energy, Day 2 reliability collapses.

This is why pumped hydro, reservoir hydro, and dispatchable thermal still dominate reliability worldwide.

India, however, is trying to solve energy-duration problems with power-duration tools.

6. Storage Is Being Forced into Roles It Should Never Play

Storage is increasingly expected to:

·         Firm renewables

·         Replace peaking coal

·         Provide spinning reserve

·         Act as transmission substitute

·         Improve adequacy

·         Reduce curtailment

Each role has different technical and economic requirements.

Forcing one technology to do all of them results in:

·         Overpayment for some services

·         Under-delivery for others

·         Regulatory disappointment later

A 2-hour battery is excellent for:

·         Frequency regulation

·         Short ramps

·         Local congestion relief

It is not a substitute for:

·         Seasonal balancing

·         Capacity markets

·         Energy security

7. The Capital Misallocation Risk

The most dangerous outcome of the storage mirage is not technical failure—it is capital lock-in.

Once:

₹1–2 lakh crore is sunk into short-duration BESS

Tariffs are socialised

Balance sheets are exposed

…the system will defend these assets even if they underperform.

This is how structural inefficiencies become permanent.

India has seen this movie before—with stranded thermal assets, take-or-pay PPAs, and excess baseload.

8. What a Smarter Storage Strategy Would Look Like

A rational approach would start not with technology, but with system diagnostics:

·         Classify shortages

·         Ramp vs energy vs adequacy vs contingency

·         Match duration to risk

·         <1 hour → batteries

·         2–4 hours → batteries + peakers

·         8 hours → hydro, thermal, demand response

·         Pay for outcomes, not assets

·         Scarcity-linked payments

·         Availability during stress hours

·         Capacity value, not nameplate MW

·         Let storage compete, not dominate

·         Against peakers

·         Against demand response

·         Against hydro flexibility

9. BESS biddings are speculative

The recent SECI discovered tariff of ₹3.12 per kWh, a global floor, for the 1200 MW solar + 600 MW/3600 MWh (6-hour) storage project marks a significant moment in India’s renewable energy evolution, signalling strong competitive pricing even with embedded storage. Technically, this blended price assumes aggressive optimisation: high solar DC/AC ratios to absorb charging losses, ESS sized for daily peak obligations without adverse degradation, and seamless grid compliance under CEA/IESC standards. The structure also places all firming risk on the developer, requiring precise metering, forecasting, and dispatch control to meet the 3 MWh/MW daily peak supply, tight CUF discipline over 25 years, and stringent grid code requirements—all without dedicated capacity payments. The absence of separate remuneration for storage capacity or availability means developers must engineer performance to deliver firm energy reliably while maintaining battery health over multiple cycles and years.

Financially, ₹3.12/kWh is feasible only if multiple assumptions align: continuing declines in ESS costs, minimal performance penalties, and limited merchant or arbitrage cycling. Several challenges sharpen this risk profile:

• Currency (FX) risk: With a large share of battery components imported (cells, BMS, inverters), INR depreciation versus USD materially inflates capex and especially mid-life replacement costs, with no passthrough in tariffs. For context, the US dollar traded at around ₹45 in 2000 and is close to ₹90 today, implying a near-100% depreciation of the rupee over 25 years. The recently discovered ₹3.12/kWh SECI tariff therefore implicitly assumes that global BESS prices will decline by more than this currency depreciation over the project life. In effect, part of the bid’s viability rests not just on technological learning curves, but on battery cost reductions outpacing long-term INR weakness, especially for mid-life replacements where FX risk is unhedged.

• Degradation & replacement: Warranty and repowering assumptions need to hold; higher than expected degradation or delayed cost declines can erode returns.

• Penalty asymmetry: Strict peak supply penalties and CUF caps concentrate downside on developers without compensating upside.

• Unhedged future costs: O&M, insurance, and replacement costs in potentially volatile FX environments add to long-term uncertainty.

Together, these technical and financial challenges mean the headline tariff is only robust under optimistic technology and macroeconomic pathways, and substantial execution discipline is required to deliver value across a 25-year PPA horizon.

10. Conclusion

India is right to invest in storage. It is wrong to believe that any storage is good storage.

By focusing narrowly on short-duration batteries:

·         We under-solve reliability

·         Overpay for limited flexibility

·         And postpone harder—but necessary—choices

·         Storage is not a religion. It is a tool. Tools work only when matched to the job.

Until We starts buying storage for the problem it actually has, the storage boom will remain a mirage—impressive from a distance, disappointing up close.

The National Electricity Plan should include a dedicated storage plan, and its purpose must be clearly defined. Storage now affects ramping, congestion, reserves, and reliability, and leaving it implicit risks misallocation and poor value for consumers. A plan is necessary to avoid treating storage as generic capacity and to ensure it is deployed only where it actually solves a system problem. Without this, storage risks being overbuilt in low-value locations and underbuilt where flexibility is truly scarce.

Such a storage plan should be need-driven rather than target-driven, with clear differentiation across use cases. It should:

• Map system needs across time scales (minutes, hours, days, seasons)

• Separate power requirements (GW) from energy requirements (GWh)

• Identify where storage is cheaper than alternatives like hydro, gas, transmission, or demand response

• Distinguish short-duration BESS from peaking and long-duration resources

• Specify locational and reliability roles, not just aggregate capacity

The objective should be reliability and cost efficiency—not headline storage numbers.