How much warranty do you get on a home battery?

This page is about a number that is used everywhere to compare batteries and is not fit for it. We counted the stated warranty term of every home battery in our catalogue and put price per kilowatt hour next to it. The result is below, including the part that does not flatter us.

How many years of warranty do you get on a home battery?

Almost always 10 years, which is exactly why the number says so little. Of the 285 home batteries between 3 and 30 kWh in our catalogue, 263 state a term, and 216 of those state exactly 10 years. That is 82 percent. The term is the floor and the ceiling of the market at the same time, so it selects nothing for you. Worse, a longer term does not buy you a cheaper battery. The median across the whole set is € 345 per kWh, and the groups with a different term sit above that figure rather than below it. Within the 10-year group alone the price runs from € 141 to € 628 per kWh, a factor of 4.5. What does differ by brand is the condition attached underneath, and whether the warranty document exists at all.

Why the warranty term tells you very little

A property on which almost everything scores the same cannot be used to choose. That is the situation here. In practice the distribution of stated terms has one bar in it, and the handful of models around it sit on both sides without the price moving the way you would expect.

Read that last column carefully. If a longer warranty cost something, price per kilowatt hour would rise with the term, and if a shorter one bought a discount, it would fall. Neither happens cleanly. The 10-year group is the cheapest of the three, and that is not because 10 years is the sweet spot but because that group is so large that it effectively is the market. What price per kilowatt hour does track is capacity: larger packs cost less per kWh. The figures are in what a home battery costs.

What sits under the number does differ

Two brands in our own catalogue show how large that difference can be, and in both cases it comes from the manufacturer's warranty document rather than from a product brochure.

Huawei. The S1 generation LUNA2000 has a basic warranty of five years. Fifteen years is an additional term that applies only while the system stays connected to Huawei's FusionSolar cloud; if that connection drops for more than six months, the additional term lapses and the five-year basis remains. We therefore publish five years with the condition attached on 10 Huawei models, rather than the number fifteen. That is the least flattering way to write it down and the correct one.

BYD. The Battery-Box carries ten years, with two limits on it. The warranty also ends once maximum energy throughput is reached, so under intensive daily cycling the end can arrive before the calendar does. And it applies only on an inverter from BYD's compatibility list. Choose a combination that is not on it and the system may be electrically fine while the warranty is not. Which combinations are approved is on our compatibility page.

Which brands publish their warranty document

This is the check that actually matters, and our own catalogue does not come through it unscathed. Of the 285 residential batteries we carry, 170 have the manufacturer's warranty document attached to the product page and 115 do not. That absence is not evidence that there is no warranty; it means the manufacturer does not publish the conditions openly and that we have to request them for you. We do not fill that field with an assumption, because a warranty document that does not exist cannot be summarised.

Only brands with eight or more residential models appear in the table, so that a single incidental product does not make or break a brand. Pylontech, Huawei, Sungrow, Fronius and Hoymiles publish a document for every model. Felicity Solar, Growatt, Deye, SolarEdge, Regitec and Kostal publish none at all. With that second group you are buying on brand reputation rather than on readable conditions, and that is a choice you should make deliberately rather than discover by surprise.

What is a capacity warranty?

Alongside the ordinary warranty against defects in material and workmanship, almost every manufacturer makes a second promise: that at the end of the term the battery still delivers a minimum percentage of its original capacity. That is the capacity warranty, and it acknowledges something an ordinary warranty does not cover: every lithium cell slowly loses capacity through use and through age, and that is normal wear rather than a fault. What the minimum is and how it is measured differs per brand, and the figure sits in that model's warranty document. We deliberately quote no general percentage here, because it would be an average of documents we do not all hold.

Two things govern how quickly you approach that limit, and neither depends on the brand. The first is how much you actually use the battery: one full cycle a day ages it faster than three a week. The second is temperature. Charging below freezing damages LFP cells and sustained heat accelerates ageing; which spot in the house is suitable is covered in installing a home battery. Cell chemistry is the third factor, and it is precisely why we sell lithium iron phosphate only. The reasoning, with the number of models checked, is in is a home battery safe.

What you have regardless of the manufacturer warranty

A manufacturer warranty is an extra promise on top of the law, never a replacement for it. In the Netherlands you are entitled as a consumer to a product that matches what you could reasonably expect of it, and for a durable, expensive product such as a home battery that expectation is high and long lasting. That right runs against the seller, so against us, and it does not expire because a manufacturer warranty expires. We therefore do not send you to the manufacturer when something breaks: we are not allowed to, and it is not how we have set this up. How a report runs in practice, and who may file a claim per brand, is on our warranty page.

Keep three things from the day of installation: the purchase invoice, the battery's serial number and the installer's commissioning report. In any claim, statutory or manufacturer, the first question is which unit this is and whether it was installed according to the manual. Also register your product with the manufacturer if the brand asks for it, because with several brands it is the extended term specifically that lapses without registration, and there is a deadline on it.

Which batteries meet both requirements

If the term does not discriminate, the usable requirement is this: at least ten years stated and the warranty document published, so you can read the conditions before you buy. 137 models in our catalogue meet both. These are the three cheapest of those per kilowatt hour, each from a different brand. It is not a bestseller list but the outcome of exactly the criterion set out above.

To filter further yourself, the full set is in home batteries, with the stated term on every product page and, where the manufacturer publishes it, the warranty document under Downloads. Which battery otherwise suits you depends mostly on your consumption and your inverter; that is covered in which home battery is best.

How to check this yourself at another shop

Ask for the warranty document of the exact model, not for the warranty term. If you get a number back instead of a pdf, you know enough: that number is a summary nobody can verify. If the document is there, find three passages. One: does the warranty also end at a maximum energy throughput, and if so how many megawatt hours. Two: does it apply regardless of inverter, or only on an approved combination. Three: must you register or stay connected to keep the full term, and within what period. Finally, check who bears the cost of labour and shipping on a replacement, because a free part is not a free repair.

Frequently asked questions

Is 10 years a lot of warranty for a home battery?

No, it is the norm. 216 of the 263 models we list that state a term state exactly 10 years, so 82 percent. A shop presenting 10 years as an advantage is presenting the market average as an exception.

Do I pay more for a longer warranty?

No. The median across all residential models is € 345 per kWh, and the groups with a different term sit above that rather than below it. Within the 10-year group alone the price runs from € 141 to € 628 per kWh. The term does not predict price; capacity does.

Why does Huawei show five years and not fifteen?

Because on the S1 generation fifteen years is an additional term that applies only while the system stays connected to the FusionSolar cloud. The basic warranty is five years. We publish the basis with the condition attached, on 10 models, rather than the most flattering number without the condition.

Does my warranty lapse if I install it myself?

On a battery that requires a certified installer: yes, almost always. Installation contrary to the manual is an exclusion with every brand. On a plug-and-play battery you put in a wall socket this does not apply, because that is what it was built for. Which type requires what is covered in installing a home battery.

What if the manufacturer goes bankrupt?

The manufacturer warranty lapses, but your statutory right to a sound product runs against us as the seller and remains. That is one reason to check whether a brand has a service partner in Europe rather than only an address abroad. The claim route per brand is on our warranty page.