Battery warranties, decoded. Read the fine print before you sign.
"10-year warranty" is the start of the question, not the answer. What actually protects you is the guaranteed capacity left at the end, the throughput or cycle caps hiding in the middle, and the conditions that can void the lot. Here's how to decode all four — before you sign, not after.
Reviewed by the Mission Green Energy Team · Updated July 2026
What does "10-year warranty"
actually tell you?
On its own — almost nothing. Two batteries can both say "10 years" on the brochure and offer completely different protection, because the value of a battery warranty lives in four dimensions, and time is the least interesting one.
Every home battery warranty is really four separate promises stapled together, and the brochure only ever quotes the first:
- 1. Time — how many years the cover runs. Around 10 years is typical in Australia; some brands go longer.
- 2. Capacity retention — the percentage of the original usable capacity the maker guarantees still remains at the end of the term. This is the promise that decides what "still working" means.
- 3. Throughput or cycle caps — a limit on the total energy (or number of cycles) the warranty covers, often "whichever comes first" with the time limit. Cycle the battery hard and a "10-year" warranty can quietly expire early.
- 4. Conditions — the things you must do (and not do) to keep the cover alive: accredited installation and servicing, internet connectivity, operating temperature, no unapproved modifications.
Whether a battery is worth buying at all is a separate question — our honest guide to whether a home battery is worth it in 2026 covers that. This page is about the document you'll be asked to rely on for the next decade. The honest rule that connects the two: if your modelled payback is longer than the warranty's realistic life — including any throughput cap — don't buy that battery yet.
How long does the
cover actually run?
Around 10 years is the Australian norm, and a few brands go longer — Enphase warrants its IQ Battery for 15 years. But a longer headline is only better if the other three dimensions hold up.
Most quality home batteries sold in Australia carry a warranty of around 10 years. A handful of brands stretch further — Enphase offers 15 years on its IQ Battery, one of the longest in the market. You can see the warranty terms side by side for the main brands on our compare systems page.
Two honest cautions about the time number:
- A longer term with a weaker retention guarantee or a tight throughput cap can be worth less than a shorter term with strong terms. Fifteen years of cover that quietly expires on throughput in year nine is a 9-year warranty with good marketing.
- The clock usually starts at installation or commissioning, not purchase — and some warranties require registration to start (or maintain) the full term. Check which applies to your unit and do the registration the week it's installed.
The time dimension is the easy one. The next two are where warranties genuinely differ.
What is capacity retention — and why
is it the number that matters most?
The warranty doesn't promise your battery stays as good as new. It promises a floor: a percentage of the original usable capacity that must still remain at the end of the term. That floor is the real strength of the warranty.
All lithium batteries lose capacity with age and use — that's chemistry, not a defect. So no warranty guarantees your 10 kWh battery still stores 10 kWh at year 10. What it guarantees is a minimum retained capacity at the end of the term — commonly guaranteed at levels often around 70%, though the exact floor varies by brand and model. Read your document; the difference between the retention levels brands guarantee is the difference between a strong warranty and a hollow one.
Why this number matters more than the years:
- It defines what "still working" means. A battery can degrade to the guaranteed floor and the manufacturer owes you nothing — that's the deal you signed. The floor tells you the worst case you've agreed to accept.
- It changes your payback maths. A payback model that assumes full capacity for ten years is quietly optimistic; the later years store and save less. Our battery worth-it guide explains why payback has to land inside the warranty's realistic life.
- It's how a claim is actually judged. If your battery degrades faster than the guarantee, the retention clause — measured the way the document says it's measured — is what your claim stands on.
When you compare batteries — on our comparison table or in our best home battery roundup — treat "10 years at a higher guaranteed retention" versus "10 years at a lower one" as materially different products, because they are.
What are throughput
and cycle caps?
Many battery warranties don't just have a time limit — they have an odometer. Once you've put a set amount of energy (or number of cycles) through the battery, the warranty ends, even if the years haven't run out.
Throughput caps
A cap on the total energy delivered by the battery over its life, usually expressed in megawatt-hours. Every kilowatt-hour that passes through counts. Hit the cap and the warranty is done — regardless of the calendar.
Cycle caps
Some warranties count charge-and-discharge cycles instead of (or as well as) energy. Cycle-life ratings on spec sheets and warranty cycle caps are not the same thing — the warranty document's number is the one that binds.
"Whichever comes first"
The phrase to hunt for. A warranty written as "10 years or a stated throughput, whichever comes first" means heavy daily cycling can exhaust the cover years early. One deep cycle a day sits differently against that cap than three.
Can a VPP quietly
eat your warranty?
Yes — if your warranty is throughput- or cycle-capped. A virtual power plant earns its rewards by cycling your battery harder than your household would alone, and every extra cycle counts against a capped warranty.
This is one of the most under-explained interactions in the battery market. When you join a VPP, you hand a third party permission to charge and discharge your battery to suit the grid — that's the whole deal. An aggressive VPP schedule means more cycles per year than your own usage would generate, and on a throughput-capped warranty, those extra cycles are spending your warranty life. The VPP payments arrive as income; the consumed warranty leaves silently.
Three things to check before you sign a VPP agreement:
- Whether your battery's warranty is capped at all. A time-based, unlimited-cycle warranty (like Tesla's) isn't consumed by extra cycling; a "whichever comes first" throughput warranty is.
- What the warranty document says about VPP participation and third-party control. Some warranties have specific terms for it — find them before, not after.
- Whether the VPP income actually beats the cost. That's a numbers question, and we've run it honestly — including when the answer is "don't join" — in our guide to whether a VPP is worth it in Australia.
What conditions can
void the warranty?
The conditions section is where warranties are quietly lost. None of these clauses is hidden — they're just rarely read. Here are the ones that actually catch Australian households out.
Accredited install & servicing
Most warranties require installation — and often ongoing servicing — by an accredited or manufacturer-approved installer. Work by anyone else can end the cover. In Australia battery and switchboard work legally requires a licensed electrician anyway; this is never a DIY job.
Internet connectivity
Many warranties require the battery to stay connected to the internet so the manufacturer can monitor it and push firmware updates — and some reduce or void cover if it's offline for extended periods. If your wi-fi router moves or changes, reconnect the battery.
Operating temperature
Warranties specify an ambient temperature range, and installs that leave the battery baking in full afternoon sun can fall outside it. Siting is a warranty decision, not just a tidiness one — a good installer places the unit accordingly.
Modifications & repairs
Physical modification, unapproved accessories or repairs by anyone other than an approved technician are standard void triggers. If something seems wrong, log a claim — don't let anyone "have a quick look inside".
Registration & monitoring
Some warranties must be registered after installation to run their full term, and some claims lean on the manufacturer's monitoring history as evidence. Register the unit, keep your documents, and keep the monitoring app connected.
What can't be voided
No warranty document can contract away your consumer guarantees under the Australian Consumer Law. If the product isn't of acceptable quality or fit for purpose, the ACL sits above whatever the written warranty says — more on that below.
What happens if the
installer goes bust?
Less than the fear suggests — and more than the sales pitch admits. The manufacturer's warranty generally survives an installer collapse. What dies is the workmanship warranty and the after-sales support.
Here's the honest split. If the company that sold and installed your battery stops trading:
- The manufacturer's product warranty generally survives. You can usually claim it directly with the manufacturer or their Australian importer — provided they're still trading here. Your battery is not suddenly uncovered.
- The installer's workmanship warranty and after-sales support die with the company. That's the part that covered the installation itself — the wiring, mounting and configuration — and it's the door most claims walk through first. Losing it means a fault caused by the install, rather than the product, has no one left to answer for it.
- ACL guarantees against the installer become practically worthless once the company is in liquidation — the right survives on paper, but there's no one to enforce it against.
This isn't a theoretical risk. An estimated ~600,000 Australian solar systems — roughly 1 in 6 to 7 — are "orphaned" because the company that sold them has stopped trading (an industry estimate by Markus Lambert, reported by CHOICE). We've written a full guide to what to do if your solar installer has gone bust, and the prevention version is simpler than the cure: check who you're buying from before you pay a deposit, and prefer manufacturers with a genuine Australian support presence. You can read Mission Green's own warranty terms — including our workmanship cover — in full.
Does the ACL protect you
beyond the written warranty?
Yes. The Australian Consumer Law's consumer guarantees apply automatically, can't be signed away, and sit above whatever the warranty document says — including its exclusions and caps.
Every consumer product sold in Australia comes with consumer guarantees under the Australian Consumer Law: the product must be of acceptable quality, fit for purpose and match its description. These guarantees exist regardless of what the manufacturer's warranty says, they can't be excluded by contract, and for a product as expensive and long-lived as a home battery, they can extend beyond the written warranty period. A warranty document is a promise in addition to your ACL rights — never a replacement for them.
Two honest caveats so you don't over-rely on it:
- The ACL is a remedy, not a schedule. It doesn't specify retention percentages or throughput numbers — what counts as "acceptable quality" for a battery is argued case by case. The written warranty is still the document that makes your protection concrete, which is why decoding it matters.
- Your claim is only as good as the entity you can claim against. ACL rights against an insolvent installer are rights against no one. Against the manufacturer or importer, they're real — if that company still trades in Australia.
For the official wording, the ACCC's consumer guarantees guidance is the primary source — see the Sources section below.
Which five lines should you find in
any warranty PDF before signing?
You don't need to read all twenty pages. Download the actual warranty document for the exact model you've been quoted — every manufacturer publishes it — and find these five lines.
- 1. The term and its start date. How many years, and whether the clock starts at installation, commissioning or registration. Note any registration requirement and do it immediately.
- 2. The guaranteed end-of-term capacity retention. The percentage floor, and — just as important — how it's measured for a claim. This is the single strongest line in the document.
- 3. The throughput or cycle cap. Search the document for "throughput", "MWh", "cycles" and "whichever comes first". If there's a cap, sense-check it against how hard you plan to cycle the battery — especially if a VPP is in your plans.
- 4. The conditions and exclusions list. Connectivity requirements, approved-installer servicing, operating temperature, modification clauses. These are the ways cover is lost.
- 5. Who honours the warranty in Australia, and how. The named local entity, the claim process, and what's covered in a claim — parts, labour, transport — since a "covered" claim that excludes labour and freight can still cost you real money.
Then close the loop with the rule this whole page hangs on: put the warranty's realistic life — term, retention floor and any cap — next to your modelled payback from our worth-it guide. If the payback lands outside the warranty's realistic life, that battery isn't ready for you yet — pick a stronger warranty, a smaller unit, or wait.
So how should you actually use all this?
Here's what we'd tell a friend: judge the warranty on its four dimensions, not its headline — and let the warranty veto the purchase, not decorate it.
Ask for the warranty PDF for the exact model in your quote and find the five lines above — any installer who can't produce the document, or waves you past it, has told you something useful. Compare batteries on retention floors and caps, not just years: our comparison page and best-battery roundup lay the field out honestly. If your payback maths doesn't land inside the warranty's realistic life, the honest answer is wait, buy smaller or pick a different battery — and remember the manufacturer's warranty is only half the protection; the other half is choosing an installer likely to still exist when you need the workmanship cover honoured.
Battery warranties, decoded.
Your questions, answered.
Usually two or three separate promises bundled under one headline. First, a product warranty that covers defects in the battery itself for a set period — commonly around 10 years in Australia, with some brands going longer, such as Enphase at 15 years. Second, a performance guarantee that a stated percentage of the original usable capacity will remain at the end of the term. Third, a set of conditions — things like accredited installation, internet connectivity and operating temperature — that you must meet to keep the cover alive. The headline number only answers the time question. Whether the warranty is actually good depends on the guaranteed capacity retention, any throughput or cycle caps, and the conditions attached — so read the actual warranty document for the specific model, not the brochure summary.
Capacity retention is the percentage of the battery's original usable capacity that the manufacturer guarantees will still be available at the end of the warranty term. All lithium batteries lose capacity with age and use, so the warranty does not promise that a 10 kWh battery still holds 10 kWh at year 10 — it promises a floor, often around 70%, though the guaranteed level varies by brand and model, so read your document. That guaranteed floor matters twice: it tells you how much storage you can count on in the later years, and it quietly shrinks the savings in any payback calculation that assumes full capacity for the whole warranty life. A battery guaranteed to retain more of its capacity is a genuinely stronger warranty than one with the same headline years and a lower floor.
A throughput cap limits the total energy the warranty covers passing through the battery — usually expressed in megawatt-hours — while a cycle cap limits the total number of charge-and-discharge cycles. Many home battery warranties are written as '10 years or a set amount of throughput, whichever comes first', which means heavy daily cycling can exhaust the warranty before the calendar does. Not every brand does this: Tesla's Powerwall warranty is time-based with unlimited cycles for normal home use, which is one reason the fine print matters more than the headline. Find the throughput or cycle clause in the warranty document for any battery you are quoted, and if you expect to cycle the battery hard — for example in an aggressive virtual power plant — factor that into which warranty actually protects you.
It can, if your warranty has a throughput or cycle cap. A virtual power plant earns its rewards by charging and discharging your battery more often than your household alone would, and every one of those extra cycles counts toward a capped warranty. An aggressive VPP schedule can therefore exhaust a throughput-capped warranty well before the time limit — which quietly changes the value of the VPP payments. Some warranties handle this better than others: a time-based, unlimited-cycle warranty like Tesla's is not consumed by extra cycling, and some warranty documents have specific terms about VPP participation. Before you join any VPP, read what your battery's warranty says about throughput, cycles and third-party control, and weigh the VPP income against the warranty life it may consume.
The common triggers sit in the conditions section of the warranty document, not the headline. Typical ones include installation or servicing by someone who is not an accredited or approved installer, failing to keep the battery connected to the internet so the manufacturer can monitor it and push firmware updates, operating it outside its stated temperature range, physical modification or unapproved repairs, and in some cases failing to register the warranty after installation. This is why battery work is never a DIY job — in Australia it legally requires a licensed electrician, and unlicensed work can end both the warranty and your safety. Two protections sit outside the written document: the manufacturer cannot contract away your rights under the Australian Consumer Law, and a good installer will spell out the conditions before you sign rather than after a claim is refused.
The manufacturer's product warranty generally survives — you can usually claim it directly with the manufacturer or their Australian importer, provided they are still trading here. What dies with the installer is their workmanship warranty on the installation itself and their after-sales support, which in practice is where many claims start. Australian Consumer Law guarantees technically survive too, but enforcing them against a company in liquidation is usually worthless. This is a real risk to price in: an estimated ~600,000 Australian solar systems — roughly 1 in 6 to 7 — are 'orphaned' because the company that sold them has stopped trading, per an industry estimate by Markus Lambert reported by CHOICE. The honest defence is to check the installer's likely longevity before you pay a deposit, and to prefer batteries from manufacturers with a real Australian support presence.
Where this guidance comes from.
Warranty structures vary by brand and model and change over time — always read the current warranty document for the exact model you're quoted. The consumer-law and industry framing on this page draws on these primary sources.
- ACCC — warranties and consumer guarantees under the Australian Consumer Law
- energy.gov.au — solar and battery warranties and consumer guidance
- CHOICE — what to do if your solar company goes out of business (orphaned-systems estimate)
- Clean Energy Council — approved products & accreditation
- Clean Energy Regulator — home battery program & installer requirements