Home battery warranties compared: years, cycles, and throughput

A home battery warranty is not one promise. It is usually three or four limits stacked together, and whichever one you hit first is the one that ends your coverage. Manufacturers rarely present it that way. This page pulls the warranty terms out of the datasheets for every model we track and lines them up on the same page, with each figure quoted on the basis its own datasheet states.

Nothing here is estimated. Where a manufacturer does not publish a number, we say it is not published rather than filling the gap with a guess.

The three clocks in a battery warranty

Almost every warranty in our data set runs on some combination of three limits.

The first is calendar years, which is the number everyone quotes. The second is a usage cap, written either as a cycle count or as a throughput limit in megawatt-hours. The third is a capacity retention floor, the percentage of original capacity the manufacturer promises the battery will still hold when the term ends.

The years number is the easiest to compare and the least informative on its own. A 15 year term with a hard energy cap can expire sooner than a 10 year term with no cap, if you cycle the battery hard. And a term with no stated retention floor tells you nothing about what the battery will still hold at the end.

Term length, model by model

Across the models we track, terms fall into three groups.

15 years: the FranklinWH aPower 2, the Enphase IQ Battery 5P, and the Enphase IQ Battery 10C.

12 years: the Panasonic EverVolt 2.0, and the battery portion of the Qcells Q.HOME CORE, whose inverter and hub are covered 10 to 12 years rather than the same 12 as the battery.

10 years: everything else we track, including the Tesla Powerwall 3, the LG Home 8, the Generac PWRcell, the SolarEdge Home Battery, the sonnen sonnenCore+, the Anker SOLIX X1, the EG4 PowerPro WallMount, the Savant Power Storage 20, the Fortress eVault Max 18.5, the BYD Battery-Box Premium HVS, the discontinued Tesla Powerwall 2, and the discontinued SunPower SunVault.

Worth noting on the Qcells entry: a split warranty, where the battery is covered longer than the inverter and hub, is common on multi-box systems. The system stops working when any one piece fails, so the shortest covered component is the one that governs in practice.

Cycle counts and throughput caps

This is where the terms stop being comparable, because manufacturers use two different units for the same idea.

Some publish a cycle count. Of the models we track, sonnen states the highest: 10,000 cycles alongside its 10 year term, with coverage explicitly extended to the inverter, modules, and cabinet. EG4 states over 8,000 cycles at 80 percent depth of discharge. Fortress states 8,000 cycles at 80 percent depth of discharge. Both Enphase batteries state 6,000 cycles. Qcells states 6,000 cycles at 90 percent depth of discharge. Savant states 3,650 cycles.

Others publish a throughput cap in megawatt-hours. FranklinWH's aPower 2 is 15 years or 60 MWh, whichever comes first. Generac's PWRcell is 10 years or 7.56 MWh, and that figure is stated per module, not per system, so a two-cabinet stack carries a larger total allowance than the single number suggests. Savant is warrantied to 73 MWh or 3,650 cycles. EG4 lists 82.6 MWh of rated lifetime production.

A cycle count and a throughput cap are convertible only if you know the capacity being cycled, which is why the two rarely line up cleanly. FranklinWH's 60 MWh across a 15 kWh usable battery is about 4,000 full-depth equivalent cycles by our own arithmetic, which is fewer nominal cycles than sonnen's 10,000 on a 10 kWh unit but spread over a longer term. EG4's own two figures illustrate the same problem: 8,000 cycles at 80 percent depth of discharge on a 14.3 kWh battery implies more total energy than the 82.6 MWh lifetime production figure printed beside it, which tells you the two numbers rest on different assumptions rather than one being wrong.

The practical takeaway is not to rank these against each other. It is to check which limit your own usage pattern will hit first. Daily deep cycling for time-of-use arbitrage burns through an energy cap far faster than occasional backup duty does.

Capacity retention floors

Retention is the number that tells you what you actually own at the end of the term, and it is the one most often left out.

Published floors among the models we track: Enphase's IQ Battery 5P states over 60 percent capacity at up to 15 years or 6,000 cycles, and the IQ Battery 10C states 60 percent capacity on the same basis. Panasonic's EverVolt 2.0 states 70 percent capacity retained at end of term. LG's Home 8 states 70 percent capacity retained. Savant states an estimated 75 percent capacity retention at 10 years, and the word estimated is Savant's, not ours, which makes it weaker than a warranted floor.

Not published on the datasheets we cite: Tesla Powerwall 3, Tesla Powerwall 2, FranklinWH, Generac, SolarEdge, sonnen, Anker, EG4, Fortress, BYD, Qcells, and SunPower. Several of these are strong products. The absence of a published floor is not evidence of a bad battery; it is a gap in what the manufacturer commits to in public, and you should ask the installer to produce the full warranty document rather than assume a number.

Conditions attached to the coverage

Two entries in our data carry conditions worth reading before you count on the headline term.

LG's Home 8 is stated as 10 years with 70 percent capacity retained, structured as 5 years standard plus 5 years contingent on registering the product in the ThinQ app. Half the term depends on an administrative step at installation. If nobody registers it, the effective coverage is half of what the marketing implies.

BYD's Battery-Box Premium HVS carries a 10 year product warranty per the BYD Battery-Box Premium Limited Warranty Letter, and the warranty letter states that conditions apply. BYD also reaches US homes almost exclusively through the solar installer channel, with limited direct residential distribution, so for most homeowners the warranty relationship runs through the installer who specified the system rather than a direct consumer channel. Ask who administers a claim before you buy.

And the hardest case in our set: SunPower's SunVault carried a 10 year warranty, but OEM support was disrupted after the 2024 bankruptcy. We do not recommend it as a new purchase, and it is the clearest example of why the counterparty behind a warranty matters as much as its length.

What to ask before you sign

Get the full warranty document, not the brochure page. Then check four things: the year count, the cycle or throughput cap and which basis it uses, the retention floor if one exists, and any registration or installer condition that gates part of the term. Confirm which party you would file a claim with, and whether labor is covered or only the hardware.

Then check the warranty against the payback. If a battery takes 11 years to pay back and the warranty runs 10, you are racing the hardware to break even. That is one of the situations we cover in when a home battery is not worth it, and it is worth testing against your own rate and usage in the calculator before the warranty term becomes the deciding factor.

Every figure on this page is drawn from the manufacturer datasheets we cite on each model's page in our battery database, verified July 2026. Manufacturers revise warranty terms, so confirm the current document for the exact unit you are quoted.