How long does a Tesla Powerwall last? Warranty math and degradation

Search for how long a Powerwall lasts and you will find confident numbers: fifteen years, twenty years, a percent of capacity lost per year. Tesla publishes none of them. There is no service-life figure on the Powerwall 3 datasheet, none on the Powerwall 2 datasheet, and none in the warranty.

What Tesla does publish is a contract, and it is unusually specific. We read the current Tesla Powerwall Limited Warranty (USA) in August 2026, revision 2.6, effective date May 6, 2026, at Tesla's own energy document library. Everything below is what that document guarantees, plus arithmetic on its own numbers where we say so. Nothing here is a prediction of how long your battery will keep working, because no manufacturer figure supports one.

What the warranty actually promises

One document now covers the whole Powerwall line. Revision 2.6 lists Powerwall 2 AC, Powerwall+, Powerwall 3 and Powerwall 3 Expansion, along with the Gateway, Backup Gateway, Backup Switch, Gateway 3, and the Tesla and Neurio energy meters. Its two core promises:

• Free from defects for ten years following the initial installation date.
• 13.5 kWh of energy capacity on the initial installation date, retaining 70 percent at ten years, expressed as a percentage of that 13.5 kWh rated capacity.

Then comes the part most summaries drop, the operating limitation attached to the retention promise. The warranty splits by how you use the battery:

• Solar self-consumption or time-based control, and backup: unlimited cycles. The document defines solar self-consumption as storing energy from an onsite solar array and using it for daily self-consumption, time-based control as storing grid or solar energy and using it for time-of-use load shifting, and backup as storing grid or solar energy and using it as backup power.
• Any application not listed above, or any combination that includes one not listed: 37.8 MWh of aggregate throughput, measured at the battery AC output.

Same 70 percent retention promise in both rows. What changes is which limit runs out first.

Capacity retention and throughput are two different clocks

A capacity-retention guarantee answers "how much will it still hold". A throughput cap answers "how much energy may pass through it before coverage ends". Confusing the two is the single most common mistake in Powerwall lifespan writing, so take them one at a time.

The retention floor. Seventy percent of 13.5 kWh is 9.45 kWh, by our own arithmetic on Tesla's figures. That is the guaranteed minimum at year ten, not an estimate of where your unit will actually land. Tesla publishes no year-by-year curve, so anyone showing you a degradation graph for Powerwall built it themselves. If your unit falls below the floor within the term, that is a warranty matter; above it, there is nothing to claim even if the loss annoys you.

The throughput cap. 37.8 MWh is 37,800 kWh. Divided by the 13.5 kWh rated capacity, that is 2,800 full-depth equivalent cycles, again our arithmetic on Tesla's published numbers. At one full charge and discharge every day, 2,800 cycles arrive in about seven and a half years, comfortably inside the ten-year term. So for an owner in the capped bucket, the energy limit is the binding one, and the ten-year headline overstates the coverage they will actually get. For an owner in the unlimited-cycles bucket, the cap never binds and the calendar is the only clock.

Two caveats on that arithmetic. It assumes full-depth cycles, and real cycling is partial, so the equivalent-cycle count is a conversion rather than a count of days. And the cap is measured at the battery AC output, so round-trip losses on the charging side do not count against it.

Which bucket you are in, and which document applies

The unlimited-cycles row covers the three uses that describe most residential Powerwalls: solar self-consumption, time-of-use shifting, and backup. The capped row is aimed at everything else. If any part of how your system operates falls outside the three listed applications, the warranty puts the whole thing under the 37.8 MWh cap rather than apportioning it. That is worth reading carefully before you enroll a Powerwall in a program that dispatches it for something other than your own home's use.

The other variable is which revision governs your unit. Warranty documents are versioned, and the one in effect at your installation date is the one that applies. The difference is not cosmetic. The 2017 Powerwall 2 AC Limited Warranty, revision 1.4, effective April 19, 2017, carries the same ten years, the same 70 percent at ten years, and the same 37.8 MWh figure, but its unlimited-cycles row reads "solar self-consumption/backup only". Time-based control is not on that list. On the plain wording, an owner installed under the 2017 document who shifts load on a time-of-use plan is in the capped bucket, while the identical usage under revision 2.6 is uncapped.

Remedies differ between the two revisions as well. Both let Tesla choose between repairing the unit, replacing it with an equivalent new or refurbished product, or refunding the market price of an equivalent product at the time of the claim. Revision 2.6 adds that where the repair or replacement work is done by a Tesla Certified Installer, the warranty includes reimbursement of reasonable labor costs to that installer, per Tesla's standard policies. The 2017 document carries no equivalent labor language, and states outright that Tesla's liability under the warranty shall not exceed the amount you paid for your Powerwall. In both, a repair or replacement inherits the remainder of the original term rather than restarting it.

If you own a Powerwall, the practical step is to get the copy of the warranty that was in force on your installation date, not whichever version is on the website today.

The conditions that can cut the term short

Tesla's ten years is conditional, and the conditions are spelled out rather than hidden:

• Internet and registration. Tesla requires the ability to push remote firmware upgrades. If the unit is offline for an extended period or was never registered, Tesla says it may not be able to honor the full ten-year term, but will always honor at least four years from first installation, subject to the document's exclusions and limitations.
• General exclusions. No coverage for defects or capacity shortfall from abuse, misuse or negligence, installation or operation contrary to Tesla's specifications and manuals, force majeure events, repair or modification by anyone other than Tesla or a Tesla certified installer, opening the external casing by anyone other than Tesla, or removal and reinstallation at a location other than the original site without Tesla's express written consent. That last one is why a secondhand unit is a harder purchase than it looks.
• Not a life-support device. The warranty states in capitals that Powerwall is not intended for use as a primary or backup power source for life-support systems or other medical equipment, and disclaims liability for such use.
• Arbitration. Disputes go to individual arbitration under AAA consumer rules unless you opt out in writing within 30 days, and class claims are excluded.

Two terms work in the owner's favor. A subsequent owner who provides proof of ownership can make claims, so the coverage follows the equipment when you sell the house. And the Tesla Solar Shutdown Device, where one is installed in a Powerwall system, carries its own 25-year defect warranty.

What the hardware datasheets add

Neither datasheet publishes a lifespan either, but both anchor the capacity number the warranty is written against.

The Powerwall 3 datasheet lists nominal battery energy of 13.5 kWh AC, footnoted as a value at 25C (77F) at beginning of life, with a 10-year warranty line in the same table and 89 percent solar to battery to home and grid efficiency, footnoted as a typical solar shifting use case. A Powerwall 3 Expansion unit is also 13.5 kWh nominal and is covered by the same warranty document. The Powerwall 2 datasheet lists 14 kWh total energy and 13.5 kWh usable, a 90 percent round trip measured AC to battery to AC at beginning of life, and the same 10-year warranty line. Full spec detail sits on our Powerwall 3 and Powerwall 2 model pages.

Note the phrase "beginning of life" on both. Every headline capacity and efficiency figure Tesla publishes is a new-unit number, which is exactly why the retention floor in the warranty is the more useful figure for a question about lasting. The rest of the current unit's published figures, including power and dimensions, sit on our Powerwall specs page.

What this does not tell you

It does not tell you the battery stops at year ten. It does not tell you it keeps going either. A warranty is a floor under the manufacturer's obligation, not a forecast of hardware behavior, and Tesla has published no service-life estimate we can cite for Powerwall. Where a maker does publish more, we say so: several batteries in our set state cycle counts, throughput allowances, or retention floors on very different bases, and they are collected in the warranty comparison guide.

So the honest answer to "how long does a Powerwall last" is this. Tesla guarantees ten years of defect coverage and at least 9.45 kWh of the original 13.5 kWh at year ten, with unlimited cycling if your use is solar self-consumption, time-of-use shifting, or backup, and a 37.8 MWh ceiling if it is anything else. Beyond that, you are into territory no published document covers. If you are weighing Powerwall against other units on warranty terms rather than lifespan claims, the alternatives compared by datasheet puts the published terms side by side.