Tesla Powerwalls, Panasonic Evervolts, and sonnen eco – all of these batteries come with a 10 year warranty. However, simply comparing the length of one warranty term to the next doesn’t give you a full picture: what is and isn’t included in a warranty differs quite a bit from one battery company to the next. And considering how important a battery system is for resiliency and–in some markets–savings, you want to make sure you’re covered in case anything goes wrong.
In this article, we’ll review the most important aspects of a battery warranty, and discuss what’s standard for the industry.
- Most homeowners install energy storage systems with lithium-ion batteries.
- The most popular residential batteries typically come with at least 10 years of protection, though it can be shorter depending on how often you charge and drain your battery.
- Sometimes, battery warranties won’t reimburse any labor costs associated with installing new equipment or shipping new products.
- Use the EnergySage Marketplace to find the right solar-plus-storage set up for the right price.
Battery system warranties at a glance
|Product and performance||10 years, plus a cycles or throughput clause|
|End of warranty capacity||60%|
|Labor for repairs/ replacements||No|
|Shipping of parts||No|
|Limitations and exceptions||Variable|
|Warranty fulfillment & manufacturer reputation||Variable|
A quick note about industry standards for battery warranties
For industry standards and other factors discussed in this article, we take into account the most popular residential energy storage systems, all of which have lithium-ion batteries (e.g. lithium-iron phosphate, LFP, or lithium nickel manganese cobalt oxide, NMC). Importantly, batteries of different chemistries–like lead acid–have shorter lifespans, and therefore typically have shorter warranties and different terms than what you see here.
Product and performance warranty
Industry standard: you’ll get at least 10 years of coverage with most battery systems. However, your coverage may not last that long if you hit certain usage outputs first.
A battery’s product and performance warranty covers the integrity and output of your system. If your battery system has a defect or experiences unreasonable degradation, that’s where your product warranty kicks in.
As you’re comparing battery options, you’ll notice that most popular energy storage systems come with a 10 year warranty, and of course, longer product warranties are more favorable. However, many battery warranties will also include a clause suggesting that the term could be shorter depending on your use of the battery – this is where cycles and throughput come into play.
Each time you drain and charge your battery is known as 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, many manufacturers guarantee a minimum number of cycles as part of their warranty agreement. But read this line carefully: oftentimes, 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 (e.g. 10,000 cycles) before your battery hits its 10th birthday, it could end your warranty term.
A throughput warranty is 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 (i.e. 10 years) is up.
It’s hard to give you a number for what to expect for a throughput warranty because the numbers 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 total throughput).
End of warranty capacity rating
Industry standard: many manufacturers will guarantee that your battery will still hold at least 60 percent of its original capacity by the end of your warranty term.
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.
In most cases, battery manufacturers ensure at least 60 percent of a battery’s original capacity at the end of 10 years. For an example of what this looks like, consider the LG Chem RESU 10H: it has a capacity of 9.8 kWh, and LG’s warranty ensures that you’ll have roughly 60 percent of that capacity at the end of your warranty term. This means by the end of your warranty, your battery should still have 5.8 kWh (9.8 kWh * 60 percent = 5.8 kWh) of capacity.
As you’re comparing the end of warranty capacity ratings across various batteries, higher percentages are better than lower percentage guarantees.
Battery replacement: what happens if your product is no longer available?
Let’s say your battery system stops working after seven years – will the manufacturer be able to provide a replacement product?
Many companies will keep older products in stock for a good amount of time, or will otherwise offer to replace your battery with a comparable, recent option. Alternatively, some manufacturers guarantee that they will provide a refund if they’re unable to replace your product.
Labor for diagnostics, repairs or replacements
Industry standard: many manufacturers do not cover labor costs as a part of their warranty agreement.
Like we mentioned above, battery companies should cover a replacement battery if you need it during their warrantied term. However, 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.
Depending on the installer you move forward with, this addition–or omission–to a warranty could be moot: some local installation companies will cover maintenance and repair costs within their own workmanship warranty. However, like equipment warranties, installer warranties vary from one company to the next, and often only cover their own installation work – not maintenance costs for properly-installed equipment.
When battery companies cover labor, they may only do so for a certain amount of time, or a certain travel distance (e.g. three hours of driving). Additionally, those that do cover costs for replacements or repairs often require some form of sign-off from the manufacturer before proceeding with the fix.
Comparing warranties: the EnergySage Buyer’s Guide
Tesla Powerwall or the LG Chem RESU – which is right for you? Using the EnergySage Buyer’s Guide, you can compare the warranties, performance, and aesthetics of top energy storage systems. There’s a lot in there, so we recommend using the filter and sorting functionalities to find the right battery for you.
Shipping of parts
Industry standard: some companies cover shipping costs for replacement equipment, but not all of them.
Say your battery system breaks, and you can get a free replacement under your manufacturer’s material warranty – is the shipping included as well?
This is an aspect of the maintenance process overlooked in some warranties. Many battery manufacturers will cover the material costs associated with the replacement part, but not necessarily the fees to ship the equipment. Or, they may be able to ship the product to a local or regional distributor, but require you or your installer to get that product to your home.
Industry standard: most battery manufacturers leave workmanship warranties to the installer.
More often than not, solar installers are the sole party responsible for providing workmanship–or labor–warranties for your solar installation – they’re performing the actual installation work, after all! However, it’s becoming increasingly common for manufacturers to offer an extra safeguard by tacking on their own workmanship warranty coverage. When applicable, it’s typically only an option if you work with specific installers in a manufacturer’s certified network: they’re putting their brand name and reputation behind their work, and want to make sure they can stand by the installer performing the installation.
Limitations and exceptions
Industry standard: every warranty–including battery warranties–has limitations and exceptions.
Unsurprisingly, battery warranties often come with a list of limitations and exceptions. These limitations aren’t meant to make it difficult for you to take advantage of the offering; at the end of the day, companies need to protect themselves from unreasonable claims.
Warranty limitations and void clauses vary from company to company, but here are a few to keep an eye out for:
- Transferability: If someone buys your home, will you be able to transfer the warranty over to them? Will you have to pay a fee to transfer the warranty?
- Installer endorsement: Do you need to work with a certified installer to take advantage of the warranty offering? If someone outside of their network repairs your system, does that void your warranty claim? Is the warranty void if you perform a DIY installation?
- Outdoors vs. indoors installation: Do you want to install your battery indoors or outdoors? Not all battery systems allow for both, and if you install in a location where it’s not certified for use, it may void your warranty. Also note if you need to keep your battery within certain temperature limits – outside or otherwise.
- Proximity to the ocean: Live on a beachfront property? (Lucky!) If so, make sure that this won’t void your warranty. Salt water can corrode casings around battery systems, so some manufacturers will void a warranty if their products are within a certain distance from saline bodies of water.
- Acts of nature: 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.
Warranty fulfillment & manufacturer reputation
Industry standard: there really isn’t one! Reputation and warranty fulfillment standards/ processes vary from company to company.
Let’s say you need to submit a warranty claim – how easy is it to do so? And can the manufacturer stand by their warranty?
When comparing one battery warranty to another, also consider the following:
- How old is the company providing the warranty? Is it a bankable company, and do they have their own insurance policies or escrow that ensure their warranties will be upheld, even if they go out of business?
- Who is on the hook for actually fulfilling the warranty? Does the manufacturer have a parent company or subsidiary who backs the warranty? Do they process claims internally?
- How easy is it to make a warranty claim? Does the manufacturer allow you (the product owner) to submit the claim directly, or do you need to contact your installer to do so? Does your installer need to come out to your property and perform a diagnostic assessment prior to submitting any claims? Do you need to ship the defective product back to the manufacturer – and if so, will they cover those shipping costs?
Unfortunately, answers to the questions above can’t always be found in warranty documents. But, we’ve started publishing some manufacturer and warranty reviews that answer these questions for top manufacturers. Your installer can also be an invaluable resource for inside scoops on warranty claims.
PSA: Don’t forget about battery inverters!
We use “battery” and “battery system” pretty interchangeably in this article, but there’s one important difference between the two: an inverter. Energy storage systems typically include both batteries and inverters, while certain batteries can be sold independently. Inverters are key to the functionality of a battery, so it’s important to make sure yours is covered! If your product includes a built-in storage-only or hybrid inverter, it’ll likely be covered in your battery’s warranty terms. On the other hand, if you pair your battery with an external, third-party inverter, expect it to come with a different warranty agreement than your battery.
The best way to compare battery options – warranties and all
The key to finding the right solar panel system for your home is 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. If you have a preference for one type of battery over another, simply note it in your account when you sign up so installers can quote you accordingly.