Battery energy storage

Battery energy storage systems

As pioneers in battery storage, we design, integrate, install and maintain BESS for factories, commercial sites, solar plants and grid projects, from single cabinets to multi-MWh containers.

Does storage pay here?What's inside a BESS
Fig.: Container and cabinet formats. Schematic, not to scale.

What a battery does

What a battery can do on your site

Most sites combine several of these jobs, and the energy management system (EMS) decides which comes first.

Fig.: Several jobs, one battery. Schematic, not to scale.

  • Peak shaving & contract demand

    Trim the 15-minute maximum demand you're billed on; the saving depends on your contract demand.

  • Time-of-day shifting

    Charge in cheaper hours and discharge in the tariff's peak windows.

  • Solar shifting

    Store midday solar and use it after sunset instead of exporting or curtailing it.

  • DG hybrid operation

    Cover short outages and light loads, so the genset starts less often.

  • Backup & ride-through

    Keep critical loads running through outages and dips, where the system is designed to island.

  • Power quality & power factor

    With spare PCS capacity, supply reactive power and smooth fast load swings.

  • EV charger buffering

    Let fast chargers draw short bursts from the battery instead of the grid connection.

We don't publish savings percentages; we work them out from your own bills and meter data.

Tamil Nadu tariff

A battery's day on the Tamil Nadu tariff

Tamil Nadu's HT tariff adds 25% in the two peak windows and takes 5% off overnight, so the battery charges off-peak and discharges into the peaks.

Fig.: One day of battery duty on a Tamil Nadu HT tariff. Schematic, not to scale.

Tariff bands through the day

  1. 00:00–05:00Night rebate (−5%) · battery charges
  2. 05:00–06:00Normal · battery holds
  3. 06:00–10:00Morning peak (+25%) · battery discharges
  4. 10:00–16:00Normal · solar hours · battery charges from solar
  5. 16:00–18:00Normal · battery holds
  6. 18:00–22:00Evening peak (+25%) · battery discharges
  7. 22:00–24:00Night rebate (−5%) · battery charges
As of . A revised tariff order was pending.

Rates set for FY2022-23 to FY2026-27, ending 31 March 2027; the next order may change them.

Source: TNERC, Tariff Order No. 6 of 2025 (opens in a new tab) (30 June 2025, effective 1 July 2025).

Inside a BESS

What's inside a battery system

Cells store the energy; the other parts keep it safe, convert it and decide when to use it.

Fig.: From cell to container. Schematic, not to scale.

  1. Cell

    Lithium iron phosphate (LFP) cells of about 3.2 V each, where the energy is stored.

  2. Module

    Cells in series with busbars, sensors and a module BMS.

  3. Rack

    Modules in series with a rack BMS, fuse and contactor.

  4. Battery management system (BMS)

    Watches voltage, current and temperature, balances cells and trips on limits.

  5. Container or cabinet

    Racks plus cooling, detection, suppression, venting and an emergency stop.

  6. Power conversion system (PCS)

    The two-way inverter between the battery's DC and your AC network.

  7. Transformer & switchgear

    Connect the PCS to your LT or HT network, with protection relays.

  8. Energy management system (EMS)

    Decides when to charge and discharge, and talks to meters, solar, gensets and chargers.

Formats & chemistry

Formats and coupling options

Outdoor cabinets

All-in-one units of a few hundred kWh each, paralleled for more. Suits factories, hospitals and campuses.

Containers

Multi-MWh containers with separate PCS and transformer skids. Suits large plants, solar farms and grid projects.

Fig.: AC coupling. Schematic, not to scale.

AC-coupled

The battery has its own inverter on your AC network: the usual way to add storage to existing solar.

Fig.: DC coupling. Schematic, not to scale.

DC-coupled

Battery and solar share one inverter. Suits new hybrid plants and captures solar that would be clipped.

Source: NREL (now NLR), Evaluating the Technical and Economic Performance of PV Plus Storage Power Plants (opens in a new tab) (August 2017).

Why LFP

Lithium iron phosphate (LFP) is the default for stationary storage: long cycle life, good thermal stability and no cobalt or nickel. It made up over 90% of stationary storage installed worldwide in 2025.

Source: IEA, Global EV Outlook 2026: Electric vehicle batteries (opens in a new tab) (2026).

Safety

Layers of battery safety

Good design makes faults unlikely, catches them early and stops them spreading. The CEA's BESS safety chapter applies from 1 April 2027.

Fig.: Layers of protection, cell to site. Schematic, not to scale.

  1. Prevention

    Qualified LFP cells, cell-level BMS monitoring and a two-fault-tolerant design.

  2. Detection

    Monitored smoke, gas, heat and flame detection, with door and ventilation alarms.

  3. Suppression

    Automatic fire suppression in every battery container.

  4. Explosion control

    Forced ventilation with automatic louvres, and shutdown if ventilation fails.

  5. Separation & security

    Spacing between enclosures, fencing at least 1.8 m high, CCTV and intrusion alarms.

  6. Response

    Emergency stops and an independent fire-safety audit, as the CEA requires, plus an emergency plan shared with the local fire service.

The chapter covers BESS connected above 650 V; we design smaller systems the same way.

Source: CEA, CEA (Measures relating to Safety and Electric Supply) Amendment Regulations 2026 (opens in a new tab) (Gazette, 30 March 2026).

Standards

Standards we specify and test to

Certification belongs to the equipment maker, not to us: we specify certified equipment, check its test reports and commission to these methods.

Standards by level.
LevelStandardsWhat it covers
Cell & batteryIEC 62619 (+ IEC 63056) or UL 1973Lithium cell and battery safety
SystemUL 9540 or IEC TS 62933-5-1 + IEC 62933-5-2Whole-system safety
Fire test dataUL 9540AFire test method, not a certification
Performance testsIEC 62933-2-1 (IS 17067 Part 2/Sec 1)Energy and efficiency, tested yearly
Installation practiceNFPA 855 (2026 edition)Installing stationary storage
IndiaCEA Safety & Construction amendments 2026Binding from 1 April 2027

Performance

How we quote performance

  • Round-trip efficiency, AC to AC

    Measured at the meter including auxiliaries, as the CEA's 2026 standards define it (minimum 70%).

  • Degradation & augmentation

    The CEA's minimums are 90%, 80% and 70% of output at 5, 10 and 15 years; we plan augmentation where needed.

  • Usable energy

    We size for the energy you need delivered; the CEA's minimum depth of discharge is 80%.

  • Warranties, back-to-back

    We check the maker's warranty terms and line our commitments up with them.

Fig.: Capacity steps down with age; augmentation lifts it back. Schematic, not to scale.

Source: CEA, Technical Standards for Construction of Electrical Plants and Electric Lines (Amendment) Regulations, 2026 (opens in a new tab) (Gazette, 23 June 2026).

Scale

Sites and project sizes

Behind the meter

Design, EPC, integration and O&M for factories, hospitals, campuses and commercial buildings.

Solar + storage

New hybrid plants, and storage added to existing rooftop, captive and ground-mount solar.

Developers & utilities

Owner's engineering, FAT witnessing, balance-of-plant, commissioning and O&M for grid-connected storage in southern Tamil Nadu.

Illustrative. Schematic, not to scale.

Ways to pay for storage

Existing systems

Existing systems and the 2027 rules

From 1 April 2027, the CEA's safety chapter applies to batteries connected above 650 V, including an independent fire-safety audit.

Fig.: The CEA's BESS safety chapter applies from 1 April 2027. Schematic, not to scale.

  • Readiness review

    We check your system and records against the chapter and list the gaps.

    See our consulting services

  • Audit preparation

    We gather the documents and test records the auditor will ask for. We don't act as the auditor.

  • Take over the upkeep

    A baseline inspection and capacity test, then an AMC.

    How O&M takeovers work
Book a readiness review

Source: CEA, CEA (Measures relating to Safety and Electric Supply) Amendment Regulations 2026 (opens in a new tab) (Gazette, 30 March 2026). Regulations 122(M) and 122(N).

Buyer's checklist

Questions to ask any supplier

Fig.: A supplier checklist, ticked one by one. Schematic, not to scale.
  1. Which certificates cover the cell, the pack and the whole system?
  2. Can we see the UL 9540A test report, and at which level?
  3. Is round-trip efficiency AC to AC, including auxiliaries?
  4. What degradation curve does the warranty commit to?
  5. Who services it locally, how fast, and with which spares?
  6. Does the design meet the CEA 2026 BESS regulations?

Questions about battery storage

A BESS is a stationary battery with its own power conversion, software and safety systems, built to cycle daily with the grid, solar and generators. A UPS battery backs up specific loads briefly and mostly sits idle.

It can, when it does several jobs: trimming maximum demand, avoiding peak-hour energy, storing surplus solar and cutting DG running. We work out the value from your bills and 15-minute data; we don't promise a percentage.

For short outages often yes, if the system is designed and approved to island. For long outages a hybrid works better: the battery takes short interruptions and the DG set runs less.

Usually, with an AC-coupled battery that has its own inverter. We check your solar inverter, its warranty, your metering, protection and space first.

It depends on cycling and temperature. NREL's planning figure is about 15 years with augmentation, and the CEA's 2026 standards set minimum output of 90%, 80% and 70% at years 5, 10 and 15.

Start with a conversation

Talk to us about battery storage

A phone call is enough to start. Twelve months of bills and meter data, if you have them, help us come back with a first view.

Call +91 7200788891WhatsApp (opens in a new tab)info@che-energy.in