sonnen battery warranty review

Let's face it – warranties aren't the easiest (or most gripping) documents to read. There are often a lot of details and fine print included that can be hard to digest, leaving many to wonder: what does the warranty actually cover? Am I vulnerable? Anything I might be missing?

To make it as easy as possible, we've read warranty documents for the top solar battery manufacturers, talked to them to confirm what is and isn't included, and plan to point out the most important aspects of each in a series of articles. In this article, we'll break down the warranty of one of the biggest names in energy storage: Sonnen.

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Sonnen was founded in Germany in 2010 and quickly became a global leader in energy storage technology. They have a presence across the globe, from Australia to the United States, and focus solely on home battery storage solutions. Sonnen has installed over 90,000 batteries to date and continues to innovate and iterate on their storage offerings.

Currently, sonnen produces three batteries: the sonnenCore, sonnen eco, and sonnen ecoLinx. The sonnenCore and eco both have a 10-year, 10,000-cycle warranty, and sonnen guarantees that the battery will maintain at least 70 percent of its capacity to hold a charge for the duration of the warranty period. The ecoLinx is sonnen's "luxury" battery offering – in addition to being a battery, it is also a system that syncs your entire home's energy usage and intelligently manages it to ensure maximum efficiency. The ecoLinx has a 15-year, 15,000-cycle warranty with an end-of-warranty charge capacity of 65 percent.

sonnen's battery warranty at a glance

Product and performancesonnenCore and eco: 10 years, 10,000 cycles sonnen ecoLinx: 15 years, 15,000 cycles10 years, plus a cycles or throughput clause
End of warranty capacitysonnenCore and eco: 70% at year 10 ecoLinx: 65% at year 1560% at year 10
Labor for repairs/ replacementsYesNo
Shipping of partsYesNo
TransferabilityYes, no feeYes, no fee

A battery manufacturer's product and performance warranty covers the integrity and output of the equipment itself – if your battery system has a defect or experiences unreasonable degradation, that should be covered by your product warranty. If there's a defect with your battery, you or your installer should be able to tell that something is amiss and fix the problem immediately–often before the battery is ever installed. Regardless, it's good to consider products with longer warranties for the peace of mind it provides.

Sonnen includes a 10-year product warranty for their SonnenCore and eco batteries and a 15-year product warranty for their ecoLinx battery. You can review and compare sonnen's batteries in the EnergySage Buyer's Guide.

You'll also notice that many battery warranties will include a clause suggesting that your term may be cut short depending on your battery use – this is where cycles and throughput come into play.


Every time you drain and charge your battery, it's called a "cycle." Like the battery inside your cell phone, your solar battery will gradually lose its ability to hold a full charge the more you use it. Because of this, some manufacturers guarantee a minimum number of cycles as part of their warranty agreement. But read this line carefully: often, manufacturers will guarantee a fixed product term OR a minimum number of cycles, whichever comes first. This means if you hit the warrantied number of cycles before your battery reaches its warranty period, it could end your warranty term. The confusing part here is that manufacturers will sometimes define a "cycle" differently–i.e., how much your battery needs to be drained and charged for it to be considered a "cycle"?

Sonnen defines a "cycle" as the time it takes the battery to fully charge and discharge and includes a warrantied number of 10,000 cycles for their sonnenCore and eco batteries and 15,000 cycles for their ecoLinx battery.


Another clause that some manufacturers will put on their warranty pertains to throughput: the total energy a manufacturer expects the battery to deliver throughout its lifetime. Companies state these warranties in terms of megawatt-hours (MWh). For example, if your battery company provides a throughput warranty of 30 MWh, this means that the warranty is valid until the battery stores and delivers 30 MWh–or 30,000 kilowatt-hours (kWh)–of energy. Similar to a cycle life warranty, throughput warranties typically only apply if your battery delivers a set amount of energy before its warranty period is up.

Throughput numbers will vary quite a bit depending on the overall storage capacity of your system. Additionally, if your battery system contains several different battery cells–or modules–within it, your warranty may state a throughput by cell (which you can multiply by number of cells to get the total throughput).

Sonnen does not include a throughput warranty for any of their batteries.

In addition to providing cycle or throughput warranties, most manufacturers also promise a certain level of performance by the time your warranty is up. This often presents itself as an end-of-warranty capacity rating.

As you're comparing the end-of-warranty capacity ratings across various batteries, higher percentages are better than lower percentage guarantees.

Sonnen includes an end-of-capacity rating of 70 percent for their sonnenCore and eco battery and 65 percent for their ecoLinx battery.

Sonnen's battery end-of-warranty capacity

(Click to sort ascending)
Sonnen Core
Eco Linx
Warranty length10 years10 years15 years
Initial usable capacity (kWh)10 kWh20 kWh30 kWh
End of warranty capacity (kWh)7 kWh14 kWh19.5 kWh

Battery companies should cover a replacement battery if you need it during their warrantied term–but while the manufacturer may cover your replacement part, that doesn't necessarily mean they'll cover the labor costs to re-install that equipment. In fact, many manufacturers do not reimburse for labor associated with diagnostics, replacements, or repairs of their products.

More often than not, installers are the sole party responsible for providing workmanship–or labor–warranties for your battery installation. However, some manufacturers offer additional protection by tacking on their own workmanship warranty for a limited number of certified installers in their network. Sonnen does cover labor associated with removal and reinstallation as long as a sonnen-certified installer is performing the removal and reinstallation.

You can learn more about manufacturer endorsements and how they impact installer warranty offerings in this article.

Ideally, your storage system will continue operating smoothly for 10+ years, and you never have to worry about sonnen's warranty. However, if you experience any defects or performance issues with your equipment, sonnen will be there to help.

If you notice an issue with your battery, your first phone call should be to your original installer: having designed and installed your system, they are the most equipped to diagnose (and fix!) any potential issue. If you can't get in touch with your installer, or if they've gone out of business, you can contact a certified sonnen preferred partner installer to help you.

You can also reach directly out to sonnen during the warranty period if there are issues that the installers are unable to address for you or if you have trouble contacting one. If product replacement or repair is needed, you can initiate the process by filing a Warranty Labor Work Ticket, which must be completed and approved prior to any work being done to fix the issue.

When it comes time for any repairs or replacements, there are two additional warranty considerations you'll want to keep in mind: labor and shipping costs.

Labor costs for diagnostics, repairs, or replacements

Many manufacturers cover replacement parts at no extra cost but don't pay for the labor costs necessary to re-install that equipment. Sonnen will cover labor costs for removal, repair, and reinstallation; however, they specify that the work must be performed by a sonnen-certified installer and approval of the Warranty Labor Work Ticket prior to the service being performed.

Shipping of parts

Similarly, not all equipment manufacturers will pay the costs to get equipment to you – but sonnen isn't one of them! Sonnen will cover the shipping costs for any parts that need to be returned and the shipping costs for any replacement or repair parts required to fix your sonnen battery.

Every warranty has its exceptions – sonnen's is no different. Warranty limitations aren't meant to make it harder for you to take advantage of the offering; companies simply try to protect themselves from unjust or unreasonable claims.

Here are a few things that aren't covered in your sonnen warranty:

  • Batteries that are installed or worked on by anyone other than a sonnen-certified installer.

  • Batteries that are installed in improperly ventilated areas.

  • Installation in conditions that are in violation of the sonnen installation manual.

  • Acts of nature/God – this is a common one – most battery system manufacturers will not cover any damage caused by extreme weather events outside of their control, such as hurricanes, floods, earthquakes, etc. Fortunately, the hardware is pretty durable and can withstand most storms without the added protection. Even better, should damage happen to occur during a storm, many homeowner insurance policies cover damage to solar-plus-storage systems.

  • Transferability: As long as your equipment remains in the original location it was installed in, you can transfer your sonnen warranty to new owners of your system at no cost.

  • Bankability: Sonnen is a private company based in Germany and a leader in the home energy storage industry there and around the world.

  • Escrows/insurance policies: Sonnen does not have an insurance policy or an escrow account to ensure that their warranties will be upheld in the event that they go out of business.​​

  • Eligibility: Some manufacturers require customers to permanently connect to their monitoring system in order for their warranty to be valid. Sonnen's warranty requires continuous connection to the internet, aside from instances that are out of the owner's control.

  • Customer reviews: Another critical aspect of understanding a manufacturer's warranty offering is investigating how customers feel about their equipment and the services they provide. Any warranty can look promising on paper, but how the installer or manufacturer performs when honoring their warranty is also critically important. If you are interested in reading SolarEdge's reviews, you can do so here.

Finding the right storage system for your home means comparing multiple quotes from solar installers. Using the EnergySage Marketplace, you can find local solar installers near you and make easy side-by-side comparisons of all your solar-plus-storage options, including equipment. By shopping around first, you can find the right option at the right price – warranties and all. If you have a preference for one type of equipment over another–sonnen or otherwise–simply note it in your account when you sign up so installers can quote you accordingly.

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