Battery warranties: What to know

Solar battery warranties can be as complex as they are critical. With each manufacturer offering different terms, coverage options, and fine print, comparing your options apples-to-apples can feel impossible. 

Sifting through pages of dense documentation can be overwhelming (and tedious), but understanding these details is key to making a smart, long-term choice for your home. To help simplify the process for you, EnergySage has developed a scoring system that focuses on essential factors like product and power warranty terms, labor, shipping, and inverter coverage, and how easy it is to transfer ownership.

Let’s dive into some of the most popular battery brands on EnergySage and see which offers the best warranties.

A battery storage system is a decades-long investment that a warranty can help protect. The less power your system stores, the more your home may need to draw from the utility company, which eats into your savings. A good warranty ensures that if your battery experiences a problem, that it will be replaced and your investment will be protected.

We compared some of the top battery companies' warranties against each other and the industry standard. Here’s what we found:

Battery storage warranties look different from company to company and product to product, so we developed a scoring system for easier comparison. The warranty factors include:

Also known as a materials warranty, a battery’s product warranty covers the integrity of the equipment itself. If your battery has a defect or mechanical issue, if it breaks, or experiences unreasonable wear and tear, that's where your product warranty comes into play. Nowadays, most manufacturers offer at least 10 years of coverage under a product warranty, while some premium options have up to 20 years of protection against product defects.

Most battery warranty terms last for a fixed number of years or a specific usage output 

Unlike solar panel and solar inverter warranties, which last for a specified number of years no matter how much you use the equipment, many battery warranties include a cycles or throughput clause, which suggests that the term could be shorter depending on your battery use. 

Cycles clause

A battery cycle is simply the charging and subsequent draining of your battery. It works like this: Let’s say you install a battery to store excess electricity from your solar panel system. During a sunny day, your panels charge your battery to capacity. Then, when the clouds roll in and your panels aren’t cutting it, you pull from that stored electricity to power your home. You’ve just put your battery through one cycle. 

Battery manufacturers often guarantee a fixed product term or a maximum number of cycles, whichever comes first. If you hit the warrantied number of cycles (i.e., 6,000 cycles) before your battery hits its 10th birthday, it could end your warranty term. 

Here are a few things to keep in mind when comparing cycle clauses:

• A full charge in year eight won’t return the same output as a full charge in year one. As with any battery-powered electronic device, cycling your battery will diminish its output as the years go on. 

• A greater cycle allowance doesn’t necessarily mean a longer warranty term. For example, a smaller battery with a lifespan of 10,000 cycles may deliver less energy than a larger battery warrantied for only 7,000 cycles. This is where throughput energy, or the total amount of electricity a battery is warrantied to store and release, is helpful to consider. 

Throughput clause

Instead of, or in addition to, a cycles clause, some manufacturers measure this upper usage limit with throughput, or the total energy they expect the battery to deliver throughout its lifetime (typically stated in megawatt-hours, or  MWh). 

Suppose a battery manufacturer provides a throughput warranty of 20 MWh. This means the warranty is valid until the battery stores and delivers 20 MWh (or 20,000 kilowatt-hours (kWh)) of energy. Like cycles clauses, throughput warranties typically only apply if your battery delivers a set amount of energy before its warranty period (i.e., 10 years) is up. 

End of warranty capacity

In addition to providing a warranty for a set number of years, cycles, or throughput, battery manufacturers also typically offer an end-of-warranty capacity rating. This guarantees that your battery will hold a certain amount of capacity throughout the warranty. (Higher percentages are better than lower percentage guarantees when comparing the end-of-warranty capacity ratings across various batteries.)

While the warranty may cover replacement products or parts, that doesn't necessarily mean the manufacturer will cover the labor and shipping costs required to reinstall that equipment.

Your warranty likely won’t cover labor costs

Most manufacturers do not reimburse for the labor associated with replacements or repairs of their products. However, this usually isn’t an issue since many local installation companies will cover maintenance and repair costs within their own warranty agreement. 

Battery companies with outstanding warranties may cover these costs entirely or up to a certain amount of time or a certain travel distance (i.e., three hours of driving). Some manufacturers will pay for these costs by providing the company that performs the repair a rebate or check rather than reimbursing you directly.

Likewise, shipping is usually on you

Many manufacturers will cover the material costs associated with the replacement part, but not necessarily the fees to ship the equipment to your house. 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. As with labor fees, the best warranties may cover shipping but typically have an upper spending limit for what they will pay.

Most battery manufacturers leave workmanship (labor) warranties to the installer. Still, like labor and shipping costs, some companies 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.

Warranties exist to protect your purchase, but manufacturers also try to protect themselves from unreasonable claims. This is often known as the "fine print" – stated limitations and void clauses the manufacturer uses to protect itself. 

Here are a few limitations to keep an eye out for:

When you're comparing one solar battery warranty to another, consider the following:

• How old is the company that is providing the warranty? Is it a bankable company, and does it have insurance policies or an escrow to ensure its warranties will be upheld even if it goes out of business? Bloomberg New Energy Finance (BNEF) publishes lists of top-performing battery companies based on bankability.

• Who is on the hook to actually fulfill the warranty? Does the manufacturer have a parent company or subsidiary that backs the warranty or processes claims?

• 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? Does your installer need to come to your property and perform a diagnostic assessment before submitting any claims?

• What happens if you move? Does the warranty automatically transfer to the new system owner, or is it more complicated? Does the manufacturer charge a transfer fee?

Warranty transferability

Some companies offer extended product warranties at an additional cost to give you added peace of mind.

Considering today’s tumultuous electricity rates and stellar incentives, installing a solar-plus-storage system will surely pay off.

When you register for the EnergySage Marketplace, you can receive quotes from vetted, experienced solar and battery installers for free, in minutes. From there, you can choose to follow up with the installers you’re interested in (we’ll never share your contact information without permission), or connect with our unbiased Energy Advisors to help you sort through your options.