Home Battery System GuideTwo batteries can both advertise a warranty and still protect very different amounts of use. The reason is that a home battery warranty combines three separate limits, and most warranties end at whichever limit arrives first. This guide walks through the year-based term, the throughput cap in megawatt-hours, and the retained-capacity guarantee, using figures that appear on live manufacturer and EnergySage pages. Every number below is attributed to the document it came from.
The Three Warranty Structures
EnergySage describes a battery warranty as a combination of three parts that limit coverage in different ways. The first is year-based, guaranteeing coverage for a fixed number of years. The second is throughput-based, which EnergySage defines as the total energy the battery is expected to deliver over its lifetime, typically stated in megawatt-hours. The third is a capacity-retention guarantee, promising a minimum percentage of the original storage capacity at the end of the term. According to EnergySage, many warranties combine these structures and end whichever limit, years, throughput, or cycles, is reached first.
Year-Based Warranties
The most straightforward structure guarantees coverage for a fixed number of years. EnergySage reports that most manufacturers offer at least 10 years of coverage, with Tesla and Schneider Electric each offering 10 years and premium options such as Villara Energy Systems extending to 20 years. A longer term only helps, however, if the throughput and capacity limits do not expire first, which is why the year figure should never be read in isolation.
Throughput-Based Warranties
A throughput warranty caps the total energy the battery can move over its life. EnergySage lists FranklinWH at 43 MWh, Schneider Electric at 30 MWh, and Generac at 7.56 MWh per module, showing how widely these caps vary. FranklinWH, on its own warranty explainer, frames its aPower unit as a warranty of 15 years or 60 MWh throughput at 70% state of health, and uses a worksheet comparing a 15-year, 70% state-of-health, 60 MWh quote against a 10-year, 60% state-of-health, 40 MWh quote to show why the throughput number matters as much as the year term.
Retained-Capacity Guarantees
A retained-capacity guarantee promises that the battery will still store at least a stated percentage of its original capacity at the end of the term. EnergySage reports SolaX Power guaranteeing 70% at year 12 and Savant guaranteeing 75% at year 10. FranklinWH describes 60% state of health as a typical home battery warranty baseline at the 10-year mark, and positions its own 70% state-of-health guarantee as stronger than that norm. A higher retention percentage means more usable storage remains when the warranty expires.
A Worked Example: Enphase IQ Battery 5P
The Enphase IQ Battery 5P shows all three structures on a single product. According to its EnergySage equipment listing, the unit carries a 15-year term, a 6,000-cycle limit, and a 60% end-of-warranty capacity guarantee, on a battery with 5 kWh of usable energy capacity. Reading these together tells a buyer that Enphase promises the battery will still hold 60% of its 5 kWh rating after 15 years or 6,000 cycles, whichever comes first.
How to Read a Quote
Because a warranty ends at the first limit reached, comparing only the headline year number can mislead. EnergySage advises reading the year term, the throughput cap, and the retained-capacity percentage together, since a 15-year warranty can effectively end sooner if heavy daily cycling reaches the throughput or cycle cap first. When comparing two quotes, line up all three numbers, the years, the megawatt-hours, and the end-of-term capacity percentage, and treat the weakest of the three as the real ceiling on protection.