NTPC Invites EOI for Grid-Connected Sodium-Ion Battery Storage Pilot in India

September 14, 2026

NTPC Limited has invited a global Expression of Interest (EOI) for the development and installation of a pilot grid-connected Battery Energy Storage System (BESS) using sodium-ion battery technology. Issued under EOI reference NTPC/PE/ET&PR/EOI-06/2026-27, the pilot is intended to evaluate sodium-ion battery technology under Indian grid and climatic conditions before any potential larger-scale deployment.

NTPC's tender portal currently lists October 15, 2026 as the closing date for the EOI. The initiative remains at the EOI and technology-evaluation stage; no commercial-scale sodium-ion deployment should be inferred from the invitation.

It is important to be precise about what this represents: this is an Expression of Interest inviting qualified parties to come forward, not an awarded contract, and no construction, site finalisation, or commercial-scale deployment of sodium-ion battery technology has been confirmed at this stage.

NTPC has not identified a single final project site at the EOI stage. The pilot may be installed at an existing NTPC thermal power station or office building, with the final location and execution approach to be determined through the evaluation process. Applicants can provide proposals for a standardized 100 kWh usable-capacity BESS or propose a different capacity based on their standard technology configuration and demonstration requirements.

What is NTPC's Sodium-Ion Battery Storage Pilot?

According to GEAPP's own description of the initiative, the pilot is designed to explore how next-generation sodium-ion battery storage can strengthen distribution networks, improve grid reliability and voltage stability, enable greater integration of distributed renewable energy, reduce network losses, and defer costly infrastructure upgrades. The EOI is seeking organisations with experience delivering battery energy storage solutions, specifically manufacturers, system integrators, and EPC contractors, to put forward their qualifications and proposed approach for a grid-connected sodium-ion installation.

This structure, inviting expressions of interest before any request for proposal or contract award, is consistent with how NTPC has approached earlier grid-scale battery storage initiatives, including its 2021 global EOI for 1,000 MWh of grid-scale BESS capacity across its power plants, which similarly used an EOI stage to assess market interest and commercialisation prospects before proceeding to formal procurement.

Why is NTPC Testing Sodium-Ion Battery Technology?

The pilot arrives at a moment when sodium-ion technology is drawing serious policy attention in India. Speaking on the sidelines of the BloombergNEF Summit in New Delhi in August 2026, Renewable Energy Secretary Santosh Kumar Sarangi said Indian researchers working on sodium-ion batteries had reached Technology Readiness Level (TRL) 7, a stage indicating that a system prototype has been demonstrated in an operational environment, and that technologies reaching this maturity level could move from pilot projects to commercial production within two to three years.

Sarangi cited Central Electricity Authority estimates that India will need approximately 411 GWh of energy storage capacity by 2031-32, with around 156 GWh currently under process or implementation through tenders and placed orders. Sodium-ion technology is of particular interest as a potential complement to lithium-ion storage because sodium is abundant and the technology can reduce dependence on lithium and, depending on the battery chemistry, other critical battery materials. Its commercial competitiveness for grid-scale storage will ultimately depend on factors such as battery cost, energy density, efficiency, cycle life, degradation, system integration, and manufacturing scale—considerations that become increasingly important as India prepares for an estimated energy-storage requirement of approximately 411 GWh by 2031-32.

Where Could the Pilot Be Installed, and What Is the EOI Deadline?

NTPC has indicated that the sodium-ion BESS pilot may be installed at an existing NTPC thermal power station or office building. The final pilot location, capacity and mode of execution will depend on the technology selected through the evaluation process.

NTPC's tender portal currently lists October 15, 2026 as the closing date for EOI submissions under reference NTPC/PE/ET&PR/EOI-06/2026-27. The project remains at the EOI stage, with technology providers being evaluated before subsequent project execution decisions are made.

What Technical and Commercial Parameters Could the Pilot Evaluate?

Similar to how pilot-scale energy storage projects are used to validate emerging battery chemistries before wider deployment, a grid-connected sodium-ion pilot of this kind is designed to generate real-world operational data across several key dimensions.

These include technical performance under actual grid operating conditions; safety behaviour during normal operation as well as fault and stress conditions; degradation characteristics over repeated charge-discharge cycles; and the operational characteristics and techno-commercial viability under Indian operating conditions. Depending on the evaluation methodology adopted for the pilot, commercial assessment can also consider factors such as capital cost, operating cost, usable energy throughput, efficiency, degradation and lifecycle economics.

GEAPP has explicitly described the initiative as intended to generate “critical operational insights” to inform the adoption of sodium-ion technology across India's power system, indicating a structured evaluation programme rather than a purely demonstrative installation.

How Will Safety, Reliability, and Degradation Be Assessed Under Indian Conditions?

Battery chemistries that perform well in laboratory or manufacturer testing conditions do not always replicate that performance under the temperature extremes, humidity variation, and grid fluctuation patterns specific to Indian operating environments, which is precisely why a grid-connected pilot, rather than laboratory validation alone, is considered a necessary step before larger-scale deployment.

A pilot evaluation can assess reliability by tracking how consistently the system delivers its rated capacity and response time across sustained operation, while degradation assessment monitors how much usable capacity and cycle efficiency the battery retains over months of real charge-discharge cycling, rather than relying solely on manufacturer-stated cycle-life specifications. Safety evaluation can include assessment of thermal behaviour, fault response, and system-level protection performance in a live distribution network setting, which differs materially from a controlled test-bench environment.

Together, these evaluations are what would give NTPC and India's broader power sector evidence-based confidence in sodium-ion technology's suitability for grid-scale storage, rather than relying on global performance data generated in different markets and operating conditions.

Could NTPC Scale Sodium-Ion BESS Deployment After the Pilot?

Whether a successful pilot leads to larger-scale sodium-ion deployment will depend on the operational data the project generates, but NTPC's broader battery storage activity indicates the organisation has both the institutional capacity and appetite to scale a technology that proves out. NTPC has separately pursued a range of grid-scale and pilot battery storage initiatives in recent years, including a proof-of-concept BESS project at its Dadri thermal power plant in Uttar Pradesh to replace diesel generator backup, an 80 MW/320 MWh BESS tender in Kerala, and, through its subsidiary NTPC Green Energy, a 50 MW/200 MWh grid-connected BESS EPC tender at Jhansi.

GEAPP has also previously supported grid-scale BESS pilot development in India more broadly, including a 20 MW/40 MWh distribution-level BESS pilot proposed for a BSES Rajdhani Power Limited substation in New Delhi in 2023, a separate initiative that illustrates GEAPP's established role in structuring Indian battery storage pilots, though it involved a different technology and utility partner from the current sodium-ion EOI.

Secretary Sarangi's TRL 7 timeline, suggesting commercial production within two to three years for technologies at that maturity level, offers a rough sense of the horizon on which a successful pilot could translate into commercial-scale deployment, though that outcome depends entirely on how the pilot's performance, safety, and cost data hold up once the project is actually built and operated.

NTPC and GEAPP are inviting the market to help test a battery chemistry that Indian researchers say has already reached TRL 7, a meaningful maturity milestone, but still short of proven, bankable, grid-scale performance. Whether this pilot becomes the evidence base for wider sodium-ion deployment across NTPC's portfolio will depend on how rigorously its performance, safety, and degradation are measured once a system integrator is actually selected and the pilot is built.

IMARC Engineering’s Perspective

NTPC's sodium-ion BESS EOI is a significant early step in evaluating an alternative battery chemistry under Indian grid and climatic conditions, but the initiative remains at the technology-evaluation and pilot-development stage rather than representing a confirmed commercial-scale deployment.

At IMARC Engineering, we see pilot-stage energy storage projects like this as exactly the point where rigorous, independent technical evaluation matters most: performance, safety, and degradation data generated during a pilot directly shapes whether a utility the size of NTPC commits to scaling a technology across its wider portfolio, and getting that evaluation methodology right, testing under representative Indian grid conditions rather than relying on vendor specifications alone, is what gives pilot results genuine predictive value.

We support organisations evaluating emerging energy storage technologies with feasibility assessment, technology and system-integrator evaluation, grid integration engineering, and performance monitoring frameworks designed to generate the kind of rigorous, comparable data a pilot of this scale is meant to produce.

As India works toward its 411 GWh 2031-32 storage target and continues to explore sodium-ion as a complement to lithium-ion, the organisations that pair early technology interest with disciplined pilot engineering and evaluation will be the ones whose findings actually inform India's next wave of grid-scale storage investment.