The problem augmentation solves
A battery loses capacity as it ages. A well-run LFP (lithium iron phosphate) system typically fades about 2–3% a year through a mix of calendar ageing (chemistry drifting over time) and cycle ageing (wear from charging and discharging). Left alone, a battery that starts at 100% of its rated energy will hold only around 70% by year 12 to 15 — the number most warranties are written around, as we cover in round-trip efficiency and degradation.
That is a problem, because a storage contract usually promises a fixed amount of usable energy for its whole life. A DISCOM or developer that signed for, say, 1,000 MWh of dispatchable energy expects roughly 1,000 MWh in year 12 too — not 700. Something has to make up the gap. That something is augmentation.
What augmentation means
Augmentation is the planned addition of fresh battery modules to an existing system at set points during its life — most commonly around year 5 and year 10 of a 15-year contract — to top the system back up to its guaranteed usable energy. Rather than one big battery that slowly shrinks, you run a battery that gets periodically refreshed, so the usable line stays flat even as any given batch of cells ages underneath it.
There are two broad ways to hold energy flat over a long contract, and augmentation is the smarter one for most projects:
- Over-size on day one. Install far more capacity than you need at the start, so that even after 15 years of fade you still clear the guarantee. Simple, but you pay up front for years of capacity that just sits idle degrading.
- Augment over time. Install close to what you need now, then add modules later as capacity fades. You spend less capital up front and buy the later modules at future cell prices — which have kept falling year after year.
What real Indian contracts demand
Augmentation is not a theory — it is written into the biggest tenders. In SECI’s (Solar Energy Corporation of India) 600 MW / 1,200 MWh standalone BESS tender, the developer signs up for 15 years of comprehensive maintenance and must guarantee usable energy that declines from 1,200 MWh to about 840 MWh over 15 years — that is 70% retention at year 15, backed by a guaranteed round-trip efficiency near 86% and about 98% availability. Meeting that flat-ish usable-energy promise across 15 years is precisely what forces developers to plan augmentation into their bid, as explained in our guide to SECI standalone storage tenders. Most build-own-operate storage contracts run on the same 12–15 year maintenance logic.
Because these are build-own-operate obligations with liquidated damages for shortfall, the developer — not the buyer — usually carries the augmentation risk. That is a good thing for buyers, but it means the augmentation plan needs to be credible, not just a line in a spreadsheet.
What drives the augmentation plan
How much you augment, and when, depends on how hard the battery is worked:
- Cycles per year. A system cycled once a day ages faster than one cycled a few times a week, so a heavy-duty duty cycle needs earlier or larger top-ups.
- Temperature. Heat accelerates fade, so Indian sites with weaker cooling degrade faster and may need more augmentation than a datasheet assumes.
- Depth of discharge and C-rate. Running deep and fast wears cells harder than gentle, shallow cycling.
- Cell price trajectory. The cheaper cells get over time, the more attractive it is to defer capacity into later augmentation rather than buy it all up front.
This is also why an augmentation plan must be read alongside the warranty and degradation guarantees: the two documents together tell you whether a supplier’s flat usable-energy promise is actually funded.
What this means for you
If you are buying or procuring storage, do not just compare day-one capacity — ask how each bidder holds usable energy flat over the contract. A bid that quietly relies on massive over-sizing may cost more today than one with a sensible augmentation schedule, and a bid with no clear augmentation plan may quietly fall short in year 10. Ask for the assumed cycles per year, the augmentation years and sizes, and who pays for them. If you are developing a project, augmentation is a cash-flow tool as much as a technical one — deferring capacity to later, cheaper years can materially improve your returns, provided your degradation model is honest. Our standalone BESS solutions and containerised products are designed to be augmented cleanly over a 15-year life. To model how augmentation timing changes the lifetime economics for your specific duty cycle, run the numbers in our savings calculator or talk to our team.
Technical snapshot as of July 2026. Degradation rates, augmentation timing and contract terms vary by cell, design, duty cycle and tender; verify current datasheets and guarantees with your supplier before financial decisions.