Everything You Need to Know About Your Solar Battery's Warranty

Like most legal documents, warranties are long, boring and seem purposefully written to be hard to understand. But for big, expensive appliances, they're important. And for a home battery, which you rely on for backup power when the grid goes down, they're absolutely essential. 

The good news is, warranties actually aren't too tricky to read through if you learn some additional vocabulary before diving in. 

This guide will walk you through the main components of a typical battery warranty and define some terms you'll likely see. We'll highlight what's usually covered under warranty and what's not. If you're going to spend thousands of dollars on something permanently installed on your home, you want to see exactly what kind of protection plan comes with it. 

We've looked at more than a dozen solar battery warranties to see what's typically covered, how long the batteries are covered and common industry standards. Here's everything you need to know about solar battery warranties.

A breakdown of solar battery warranties 

These warranty documents are long, and there's a lot going on. But at its core, battery warranties can be separated into three main chunks: the lifespan and coverage of the battery itself, shipping and labor coverage details, and warranty exclusions or exceptions (because there's always an exception to the rules). We'll dive into what all this means in the sections below. 

We've found that many battery warranties fall into a generalized industry standard, which isn't necessarily a bad thing. Once you understand the industry standard, you can start identifying the really good warranties and the really bad ones. Most batteries on the market are warranted for 10 years and come with a 70% end-of-warranty capacity guarantee. Items like cycle and throughput coverage are a bit more scattered and can depend on the energy storage capacity of the battery. 

Years covered

This is the length of time your battery is covered under warranty. The vast majority of batteries on the market right now come with a 10-year warranty. Although, there are the occasional outliers offering 12-year or even 15-year warranties. 

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But what's really important to know is that most battery warranties will also include a cycle or throughput clause that could potentially shorten your warranty term, depending on how you use your battery. These clauses essentially put a limit on how often you can use your battery without your warranty expiring. 

Cycle count

Your battery's warranted cycle count is one of the ways a manufacturer measures the battery's expected lifespan. Every time you drain and recharge your battery, it counts as a cycle. Some battery warranties have a limit on how many times you can cycle your battery while still being covered under warranty. This is called a cycle clause. 

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In most warranties, going over your warranty's specified cycle count will cause your warranty to expire, regardless of how many years of coverage you might have had left. You either hit the specified cycle count or the specified number of years on your warranty passes, whichever comes first. Keep in mind that not every battery warranty has a cycle clause. Instead, they might have a throughput clause. In some cases, your warranty could have both. 

We found the usual battery cycle count to be around 6,000 cycles. The lowest battery cycle life we've seen is about 4,000, and the highest we've seen is 15,000 cycles. And then there's the very rare case where the manufacturer doesn't set a limit on how many times you're allowed to cycle the battery. 

We've seen only three batteries so far that offer unlimited cycles. 

When looking at a battery's cycle life, think about how you plan to use your battery. If you plan to cycle your battery daily, like for time of use offsets, virtual power plant programs or simply using your stored excess solar energy to power your home at night, then you might want to consider a battery with a higher cycle life. If you really only plan on using your battery as a backup power source during outages and emergencies, then a lower cycle life might not affect you as much. If you're not really sure what your plans are for your battery just yet, we recommend veering toward a battery with an average or higher cycle life, just in case. 

Throughput 

Your battery's throughput is the total amount of energy (typically measured in megawatt-hours) that the manufacturer expects the battery will supply throughout its lifetime. Just like with cycles, if your battery delivers its expected throughput before your warranty term passes (usually 10 years), your warranty will expire. 

The expected throughput of your battery heavily depends on the manufacturer. It's hard to really give an "average throughput" estimate for batteries because it's pretty scattered. From the batteries we've looked at, the expected throughput was usually somewhere between 30 and 50 MWh. Again, take this with a grain of salt. 

If a battery has a modular design, meaning it's made of a bunch of little batteries versus one giant battery, your warranty will most likely have an expected throughput per battery cell or module. To get your total throughput, you can multiply the stated throughput per battery cell/module by the number of battery cells/modules you're having installed.  

The performance of your battery will begin to deteriorate over time. This decrease in performance could include the output of energy you receive when you cycle your battery, making throughput a more reliable metric to measure the real value of the battery. Because of this, some manufacturers prefer to use a throughput clause versus a cycle clause. Regardless, you'll likely have one of the two in your warranty. 

End-of-warranty capacity guarantee

Your battery deteriorates over time and will start to have trouble retaining storage capacity. An end-of-warranty capacity guarantee is the manufacturer's promise that your battery will be able to retain up to a certain percentage of its original maximum capacity by the time your warranty period is over.

Most battery manufacturers will guarantee up to 70% of your battery's original capacity. So if you just bought a 10 kWh battery, the manufacturer is guaranteeing that your battery should be able to store up to at least 7 kWh of energy by the time your warranty expires. It's not unheard of for manufacturers to include a capacity guarantee of 75% or 80%, but those are few and far between. 

Shipping and labor costs

If something goes wrong with your battery and it needs to be replaced or just needs a new part for a quick repair, your warranty will cover that. What most battery warranties won't cover is the shipping of the replacement battery or part and the labor costs associated with installing the new one. If you need an installer to visit your home to diagnose your battery, the diagnosis fees will most likely be coming out of your pocket too. 

Some installers have their own workmanship warranties that will cover any of the work that the installer performs. So if your battery is malfunctioning due to a mistake your installer made during the installation process, that's something they would likely cover under their workmanship warranty. The logistics of workmanship warranties really depend on the installer.  

General warranty exclusions

One section of your battery's warranty is going to be a list of "warranty exclusions." Think of these as exceptions to the rules. It's the manufacturer laying out a bunch of different scenarios or reasons why they might not be able to cover damage to your battery, depending on the cause. 

Most manufacturers aren't going to cover any damage your battery sustains from something that's out of the manufacturer's control, like natural disasters and crime. There are other items on the list that could fall under the fault of the homeowner and you should avoid doing, such as moving your battery to another location or performing work on it without your installer.  

Make sure there's a paper trail for any work that's done to your battery, including the initial installation of the battery on your property. If you ever need to file a claim, proper written documentation of everything that's ever been done to your battery can help validate your claim. 

The most common exclusions on battery warranties include:

• Forces beyond the manufacturer's control: This is essentially a blanket term for any damage caused by accidents, product abuse/misuse, crime and unforeseen catastrophic events.
• Acts of nature: Any sustained damage from natural disasters such as earthquakes, lightning, floods and fire won't be covered under warranty.
  
• Damage from work done to your battery from a non-certified installer: Most manufacturers have a network of installers that are certified to install, commission and repair your battery. Any damage sustained from work performed on your battery, or even simply the removal of its external casing, won't be covered under warranty. Attempts to modify your battery could void your warranty.
  
• Transferring your battery to another location: Uninstalling and reinstalling your battery at another location, without the consent of the manufacturer, could void your warranty.
  
• Failure to register your product: In most cases, after you purchase a battery, you'll need to register it online with the manufacturer. Failure to do so results in a non-registered warranty. You'll usually have around 30 days after the date of purchase to register your product, but this can vary by manufacturer.
  

Frequently asked questions