The question behind every storage purchase
Two buyers can order the same 100 MWh battery system and end up with completely different projects. Not because the cells differ — often they are identical — but because of how the contract carves up the work. One buyer signs a single document with one company that hands back a working plant. The other buys containers from a supplier, hires a civil contractor, appoints their own engineer, and stitches the whole thing together.
Both are legitimate. They carry very different amounts of risk, and they cost different amounts of money — usually not in the direction people expect.
EPC stands for engineering, procurement and construction. In Indian storage procurement it has come to mean the full-service option, but it is worth separating the three contract shapes properly, because the words get used loosely in tender documents.
The three shapes
Turnkey EPC. One contractor takes the whole scope: design, engineering, supply of every component, transport, civil works, installation, testing and commissioning — then hands over a working system. The buyer “turns the key.” Crucially, one party also gives the performance guarantee.
Supply-only. The buyer purchases equipment — battery containers, the power conversion system (PCS), maybe the energy management system — and takes delivery at site or at a port. Everything after that is the buyer problem: foundations, cabling, integration, commissioning, and proving the system works.
Split scope. The middle path. The specialist equipment comes from one contractor, typically as a supply-and-supervise package, while civil works, electrical balance of plant and installation labour go to a local contractor who knows the state, the soil and the labour market. The owner, or an appointed engineer, coordinates the interfaces.
What Indian tenders actually use
Public-sector storage procurement in India has settled firmly on turnkey. Two current examples show the shape clearly.
At NTPC Ramagundam in Telangana, a 100 MW / 400 MWh system was tendered as a turnkey EPC contract covering design, engineering, supply, packing and forwarding, transportation, storage, installation and commissioning — plus the battery management system, energy management system, SCADA, power conversion system, thermal management, balance of plant, grid connection through 33 kV switchgear, civil works and site acceptance testing. The system is specified for a 20-year service life at one charge-discharge cycle a day, with 10 years of comprehensive O&M after commissioning.
The SECI 600 MW / 1200 MWh standalone project at Kolimigundla in Andhra Pradesh goes further on the operations side. Scope runs through design, procurement, manufacture, logistics, installation and commissioning up to the PCS AC output terminals, followed by a 15-year comprehensive maintenance obligation. SECI retains ownership; the contractor carries delivery and long-term performance liability without market revenue exposure.
The pattern repeats at scale. NTPC has tendered EPC packages for roughly 1,700 MW / 4,000 MWh across 11 thermal stations, split between 300 MW of four-hour duration and 1,400 MW of two-hour duration storage, and a separate 3,300 MWh EPC tender at the Khavda renewable park in Gujarat. If you are bidding into this market, you are bidding turnkey. Our guide on how to bid a BESS tender in India walks through the qualification side of that.
The guarantees are the contract
The scope tells you what gets built. The guarantees tell you what it is worth. This is where storage contracts differ most from solar, because a battery degrades in a way a panel array does not.
The SECI tender is instructive. It requires the system to hold at least 98% availability and at least 86% round-trip efficiency, with liquidated damages if those thresholds are missed. It also writes degradation into the contract as a schedule rather than leaving it to argument: dispatchable energy declines from 1200 MWh at the start to roughly 840 MWh by year 15. That is a contracted 30% fade, and meeting it is the contractor problem.
Three clauses deserve more attention than they usually get:
- The availability definition. Availability of what — the full rated power, or any power at all? Does a planned outage count against it? Two tenders quoting 98% can mean materially different things.
- The augmentation obligation. If capacity must be topped up to hold the degradation curve, who buys and installs the extra modules? We cover the mechanics in BESS augmentation explained.
- The liability cap. Liquidated damages usually cap at a percentage of contract value. If the cap is low, a long O&M obligation is worth less than it appears.
| Turnkey EPC | Split scope | Supply-only | |
|---|---|---|---|
| Parties the owner manages | One | Two to four | Several, plus own team |
| Who holds performance risk | Contractor | Shared, often disputed | Owner |
| Interface risk | Contractor absorbs it | Owner coordinates it | Owner owns it entirely |
| Headline price | Highest | Middle | Lowest |
| Financeability | Strongest single wrap | Workable with care | Hardest for lenders |
| Typical fit | Utility tenders, financed projects | Experienced developers, repeat sites | Captive C&I, in-house engineering |
Where the money really goes
A lower supply-only quote is not a saving until you have priced what it excludes. The owner picks up engineering and design, civil and structural works, cable and switchgear supply, installation labour and supervision, commissioning and testing, statutory approvals, and — least visible, most expensive — the cost of carrying performance risk with no single counterparty to claim against.
That last item is why financed projects rarely go supply-only. A lender assessing a project finance case wants one wrap and one party to pursue. Split scope can be financed, but it takes stronger sponsor covenants and a more capable owner engineer.
Where supply-only genuinely works is captive commercial and industrial installations: a factory with its own electrical team, a site where the 5 MWh container simply lands on a prepared plinth, and where the downside of a fortnight of downtime is a higher electricity bill rather than a tariff penalty.
Reading a scope boundary properly
The single most common surprise in Indian storage contracts is the interconnection boundary. When a tender says scope runs “up to the PCS AC output terminals,” everything downstream — the evacuation line, the substation bay, metering, and often the connectivity approvals themselves — sits outside. Add the usual owner obligations of land, statutory clearances, water and construction power, and a meaningful slice of project cost lives outside the EPC number you are comparing.
Comparing two bids therefore means comparing two scope definitions first, then two prices. Normalising for O&M term, augmentation obligation and the interconnection boundary changes rankings more often than not. The ongoing cost side is worth modelling separately, which we break down in BESS O&M costs in India.
Because tender terms and regulatory frameworks change by notification — CERC has recently notified a tariff framework for storage co-located with thermal stations and interstate transmission, which affects how some of these contracts are structured — treat the specific figures above as current examples rather than settled standards, and verify the live tender documents before bidding or budgeting.
What this means for you
If you are a developer bidding public tenders, assume turnkey and price the guarantee, not just the equipment. The availability threshold, the round-trip efficiency floor, the degradation schedule and the liability cap between them decide whether a keenly-priced bid is profitable or ruinous over 15 years.
If you are a C&I buyer, the choice is genuinely open. Turnkey buys you certainty and a single phone number when something fails. Supply-only buys you a lower number and a job to manage. Split scope is the sensible middle if you have built before and have an electrical contractor you trust.
If you are a lender or investor, read the scope boundary before the price. A cheap bid that excludes the evacuation line and caps liquidated damages at 5% of contract value is not cheap.
Whichever route fits, the honest comparison is total cost over the asset life against contracted performance — not rupees per kilowatt-hour on the cover page. To model that for a specific site or tender, try our BESS savings calculator or talk to our team about how a scope split would work for your project.
Contract and tender snapshot as of September 2026. Tender terms, scope boundaries and regulatory frameworks in Indian storage change by notification — verify the current bid documents before commercial decisions.