Most of the battery section of a technical bid is not written by the developer bidding it. It is assembled from documents the battery manufacturer provides, and a bid is held up more often by a missing annexure than by a disagreement over price. This page is written from that side of the table: what gets asked for, what we can put our name to, and what has to come from somebody else.
Who issues BESS tenders in India
Standalone and solar-plus-storage tenders come from central agencies, chiefly the Solar Energy Corporation of India and NTPC, and separately from state utilities and generation companies — Gujarat, Rajasthan, Andhra Pradesh, Maharashtra and Tamil Nadu among others. The state rounds are additional to the central pipeline rather than part of it, which is why a developer tracking only the central agencies sees a fraction of what is out there.
Structures differ by round, so the tender document is the only reliable statement of what any particular one requires. Where a round is supported by the central viability gap funding scheme, the terms of that scheme are set out on our page on BESS subsidies and VGF, with the government notification linked. We do not restate those figures here, because a scheme quoted twice is a scheme that eventually contradicts itself.
What the technical bid asks about the battery
The specifics vary, but the battery annexures are substantially the same from one round to the next, and every line of the following comes from the manufacturer rather than the bidder.
| What is asked for | Why it is asked, and what goes wrong |
|---|---|
| Cell safety certification | IEC 62619 for the cell actually offered. The common failure is a certificate for a neighbouring model from the same maker, which is found at evaluation rather than at submission. |
| Cell make, model and format | Prismatic, cylindrical or pouch, with capacity per cell. This fixes what can be substituted later, so it is worth agreeing before the bid rather than after the award. |
| Series and parallel configuration | How the offered MW and MWh are actually built. It has to reconcile arithmetically with the rated figures stated elsewhere in the bid. |
| Usable against nameplate energy | With the depth of discharge assumed. A bid stating nameplate and one stating usable are not comparable, and the difference is typically ten to twenty per cent. |
| Cycle life and end-of-life capacity | A cycle count without the capacity it ends at means nothing. The contract usually holds the project to a capacity at a stated year, not to a cycle number. |
| Degradation and augmentation | How capacity is expected to fall and when cells are added to hold the contracted figure. This is where the duration and daily cycle assumptions matter more than the headline capacity. |
| Fire safety test data | UL 9540A thermal runaway testing, increasingly requested alongside the suppression and detection design for the enclosure. |
| Transport classification | UN 38.3, needed for shipping the system to site whether or not the tender names it. |
| Warranty and O&M terms | Length, what is covered, and who honours it. On an assembled system the battery, the inverter and the management system can carry three different warranties from three parties. |
What we provide, and what we do not
CLN Energy manufactures lithium iron phosphate cells into packs and systems at its own plant in Noida, including containerised systems to 5 MWh, with multiple containers used on larger awards. For a tendered project we provide the battery system, the documentation above that relates to it, and the warranty behind it. Our packs are built and tested to UN 38.3, IEC 62619, IEC 61000, UL 1973 and UL 9540A, and the plant is certified to ISO 9001, ISO 14001 and ISO 45001. The full list, with what each standard covers, is on our certifications page.
What does not come from us is worth stating as plainly. Power conversion has its own standards and its certification belongs to whoever manufactures the PCS or hybrid inverter in the offered configuration. Civil works, evacuation, transformer scope and the rest of the balance of plant sit with the developer or the EPC contractor. We would rather set that boundary out now than have it discovered during evaluation, which is when it usually is.
What we need in order to quote
A useful quotation against a tender needs five things, and the first two do most of the work:
- Rated power in MW and duration in hours, which together give the energy in MWh.
- The number of full cycles a day the tender assumes.
- The end-of-life capacity the contract holds you to, and over how many years.
- Site conditions, particularly ambient temperature and whether the enclosure is outdoors.
- The commissioning date, and whether the award is phased.
Without the duration and the cycle assumption any number is guesswork, because between them they decide the augmentation plan, and augmentation moves the fifteen-year cost more than the capacity quoted on day one. The tender document itself states all five, so it is more use to us than a summary of it.
For the underlying economics rather than the bid mechanics, our guide to what energy storage costs per kWh sets out the budgeting ranges by scale, and the containerised BESS page carries the system specifications.
Specifications for the lithium battery range
Download the Lithium Solutions brochure for the range specifications, or ask the projects team about a specific rating.
Questions bidders ask
What battery certification does a BESS tender in India ask for?
The certification a technical bid turns on is IEC 62619, the international safety standard for secondary lithium cells and batteries in industrial use. It is normally submitted as an annexure naming the cell supplier, and the certificate has to match the cell actually offered rather than a similar one from the same maker. UL 9540A thermal runaway fire test data is increasingly asked for alongside it, and UN 38.3 covers transport. CLN packs are built and tested to all three.
What cell information does the technical bid need?
Make and model, cell format (prismatic, cylindrical or pouch), capacity per cell, and the series and parallel configuration that produces the offered rating. From those the bid states total energy in MWh and rated power in MW. Usable energy should be stated separately from nameplate, with the depth of discharge it assumes, because a bid evaluated on nameplate against one evaluated on usable capacity is not a like-for-like comparison.
Who provides the power conversion system certification?
Not the battery maker. Power conversion is covered by its own standards and the certification comes from whoever manufactures the PCS or hybrid inverter in the offered configuration. CLN supplies the battery system and its certification; where a project specifies a particular PCS, that documentation is provided by its manufacturer. It is worth confirming early who is responsible for each annexure, because it is a common gap found late in a bid.
Can CLN supply containerised BESS for a tendered project?
Yes. Containerised systems are built at our plant in Noida, and the range runs to 5 MWh per container with multiple containers used for larger awards. We supply the battery system, its documentation and its warranty. Scope beyond that — civil works, evacuation, transformer and the balance of plant — sits with the developer or the EPC contractor, and the split should be agreed before the bid rather than after the award.
What does a bidder need to tell a battery supplier to get a quotation?
The rated power in MW and the duration in hours, which together give the energy in MWh; the number of full cycles a day the tender assumes; the end-of-life capacity the contract holds you to and over how many years; the site conditions, particularly ambient temperature and whether the enclosure is outdoors; and the commissioning date. Without the duration and the cycle assumption a quotation is guesswork, because those two decide the augmentation plan more than the headline capacity does.
Is a Made in India battery required for a BESS tender?
It depends on the tender. Some carry local content conditions or preference under public procurement rules and others do not, so the tender document is the only reliable answer for any given round. What can be said generally is that a bid is easier to support when the cells are assembled into packs and systems in India, because the documentation, the factory inspection and the warranty all sit with a party in the same jurisdiction as the project.