Solar panel warranties: What to know

Solar panel warranties protect your solar investment and are essential to any solar installation. But, if you think comparing solar panel warranties is confusing, you're certainly not alone: Even if you take the time to sift through pages of dense documentation, understanding the differences in warranties across the various manufacturers can feel like comparing apples to oranges!

We developed a scoring system to help you compare different companies' warranties. We'll reveal which solar panel companies offer the best warranties, explain our scoring system, and discuss the important factors to consider.

A solar PV system represents a multi-decade investment. Your return on that investment directly relates to the amount of electricity your solar energy system generates year after year: The more you produce, the less you need to buy from your utility. Warranties are important because if the panels in your solar system degrade quickly over time, you'll derive less long-term value from your system than if your panels degrade more slowly.

A solar panel comes with two warranties. The product warranty covers the equipment and typically guarantees at least 10-12 years without fail. The power or performance warranty often guarantees at least 90% production at ten years and 80% at 25 years.

While deciding which solar panel to buy should be based on many factors, including cost, efficiency, power output, and performance, warranty is an important consideration. 

We compared nine of the top solar panel companies' warranties against each other and the industry standard. Based on our ranking system (explained below), SunPower offers the strongest solar panel warranty, with Panasonic, REC, and CertainTeed close behind.

Please note that warranties vary by product for some companies. The scoring system is based on the highest-performing company product for each factor. Higher ranks indicate stronger warranties.

Solar panel warranties aren't exactly straightforward, so we developed a scoring system to facilitate comparison between warranties from different solar panel companies. Each warranty factor has a unique scale determined based on its importance. The warranty factors include:

• Product: How many years does the warranty cover the integrity of the equipment itself?

• Power at year 25: What percentage of initial power output is guaranteed at year 25? This is also often referred to as a performance warranty.

• Labor: Is the work needed for diagnostics, repairs, or replacements covered by the manufacturer's warranty? Is it up to a certain dollar amount?

• Shipping: Is transporting any components needed to be diagnosed, fixed, or replaced covered?

• Extended product warranty: Can you extend your product warranty by paying more?

• Extended 30-year power warranty: Does your power warranty extend to 30 years (either automatically or at an additional cost)?

• Transferable: If you sell your house, how easy is it to transfer your warranty to the new owner? Do you have to complete any paperwork, or does it transfer automatically?

• Bankability: What happens if the company goes out of business or stops manufacturing panels? Will your warranty still be covered? We use several metrics here, as bankability can be challenging to quantify. First, Bloomberg New Energy Finance (BNEF) is an industry-standard tool; Tier 1 panels are considered the most bankable. Second, PV Evolution Labs (PVEL) conducts independent testing to assess the quality and bankability of panels and releases a list of top scorers. And third, we evaluate if companies have a separate warranty reserve, escrow, or insurance company that backs their warranties.

• Inverter: Does the warranty extend to the inverters in the system?

• Racking equipment: Does the warranty cover the racking equipment for the system?

We assessed and scored every company across each factor and weighted each factor based on importance, meaning they don't all have the same number of available points. We then summed the individual factor scores to determine the overall company score. The higher the score, the better the warranty.

We'll explain what each of these warranty factors means and how each company performed.

Also known as a materials warranty, a solar panel product warranty covers the integrity of the equipment itself. If any of your solar panels have a defect or mechanical issue or experience unreasonable wear and tear, that's where your product warranty comes into play.

Fortunately, when issues like this happen, it's usually evident "out-of-the-box": You or your installer should be able to tell that something is amiss from the get-go and fix the problem quickly–even before the panel makes it onto your roof! 

As you're shopping around for the perfect solar panel, you should expect each one to come with a product warranty, and of course, longer product warranties are more favorable. These days, most manufacturers offer at least ten years of coverage under a product warranty, while some premium options have 25 or 30 years of protection against product defects. 

Best product warranties

The following companies all offer 25-year product warranties. In addition, their warranty extends to the complete system, including inverters and racking equipment, and in the case of CertainTeed, asphalt roof shingles:

• SunPower: with SunPower microinverters

• CertainTeed: when installed by Gold installers

• Panasonic: under AllGuard Warranty, bundled with Enphase microinverters

*Silfab's 25-year product warranty pertains to systems installed by a properly registered and qualified Silfab installer; Silfab still offers a 12-year product warranty for other installers.
**REC's 25-year product warranty pertains to systems installed by a REC Certified Solar Professional; REC still offers a 20-year product warranty for other installers.

Whether you're talking about cell phones, televisions, or other home appliances, you can expect the performance of electronics to degrade over time; unsurprisingly, solar panels are no exception to this rule. Because of this, solar panel companies offer a power (or performance) warranty, guaranteeing that their products won't fall below certain output levels after set periods. 

Every power warranty has two core components: the term and the warrantied degradation rate. 

Term

Like their solar panel product warranty, manufacturers also offer a power warranty for a set time. Frankly, there's not a ton of variability regarding power warranty terms; nine times out of ten, your panels will come with a 25-year power performance warranty. However, some manufacturers–like Silfab–offer 30 years of protection.

Degradation

Solar panels degrade at slightly different rates depending on the technology used to capture sunlight, the structure of the silicon cell, and the way the panel aggregates the electricity within the panel (e.g., the layout of the actual circuitry of the solar panel). Most solar panel manufacturers will guarantee at least 80% of the original output by the end of the warranty term, or about 0.7% degradation each year.

You'll notice that most warranties expect the highest degradation (2-3%) within their first year. Interestingly, panels degrade at the highest rate when first exposed to solar radiation, and after an initial adjustment period, the panel's degradation levels to a more stable rate.

After year one, manufacturers typically ensure that power output won't fall an additional 0.5-0.7% each year of the warrantied term (or, if you're Sunpower, as low as 0.25% each year). When comparing one panel to another, remember to look at the guaranteed output by the end of year 25 and the protected degradation rate from one year to the next. 

Also, remember that a warrantied degradation rate differs from what you'll experience in real-life conditions. All solar panels undergo stringent testing to evaluate performance, and when manufacturers establish their power warranties, they stick to conservative numbers they feel confident in. For any warranted degradation rates you're considering, consider it the upper limit of expected degradation throughout the warranty period.

Best power warranties

The following companies all have power warranties that guarantee at least 92% output in year 25 for at least one of their products:

• SunPower: DC panels

• Panasonic: EverVolt panels

• REC: Alpha panels

A solar panel manufacturer may provide a product or performance warranty of 25 years that will cover a replacement panel should you need it. While the manufacturer may cover your replacement part, that doesn't necessarily mean they'll cover the labor and shipping costs necessary to re-install that equipment.

Labor for diagnostics, repairs, or replacements

Most manufacturers do not reimburse for the labor associated with replacements or repairs of their products. This addition to a warranty is a moot point for some solar shoppers: Many local installation companies will cover maintenance and repair costs within their own warranty agreement. That said, installer warranties also vary from one company to the next and often only cover their own work – not maintenance costs for properly-installed equipment. 

While most manufacturers won't pay for labor, some companies do! The best solar panel warranties will cover these costs entirely or up to a certain amount (e.g., $600 over your warranty term).

A small number of solar panel manufacturers 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. 

Shipping of parts

Say your solar panel breaks, and you can get a free replacement panel under your manufacturer's material warranty – but what about shipping that part to you or your installer?

This is an aspect of the solar maintenance process often overlooked in panel warranties. Many 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. As with labor fees, some may offer to cover shipping but have an upper spending limit for what they can pay.

Best labor and shipping warranties

The following companies cover labor for diagnostics, repairs, or replacements without a cost limit as long as the initial installation was conducted by an installer certified in the company's network; they also cover shipping of components:

• SunPower: 25 years for SunPower-affiliated installers

• Panasonic: 25 years if installed by a Panasonic Authorized installer and registered through Panasonic within 60 days of the Warranty Start Date

• CertainTeed: 25 years for Master installers, 15 years for Certified installers

*Q CELLS also offers an additional $250 labor coverage for battery storage systems.

Let's say you need to submit a warranty claim – how easy is it to do so? And will the manufacturer stand by its warranty?

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

• How old is the company providing the warranty? There's a difference between a 100-year-old company offering a 25-year warranty and a 5-year-old company offering a 30-year warranty – both exist in the solar industry. Is it a bankable company, and do they have insurance policies or an escrow to 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 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?

Best warranties for bankability & transferability

The following companies are all highly bankable, meaning they're either BNEF Tier 1 or have a separate cash reserve to ensure warranties are paid out. If you move and need to transfer your warranty to the new owner of your home, you won't have to fill out any paperwork – the warranty will automatically transfer throughout the warranty period:

• Aptos Solar: 1% cash customer reserve for every panel sold

• Q CELLS: BNEF tier 1

Some companies offer extended product or power warranties to give you added peace of mind. To be eligible for the extended warranty, you may need to choose an installer in the company's network, select a specific financing partner, or pay a fee.

Best extended warranties

Of the nine companies on our list, one offers an extended product warranty, and three offer power warranties that extend to 30 years.

• Silfab: automatically guarantees 82.6% at year 30 (no cost)

• Aptos Solar: for a fee, increases the product warranty from the 15-year baseline to 25 years and guarantees 82.4% at year 30

• Solaria: via a select finance partner, guarantees 83.5% at year 30

*Silfab and REC both technically offer extended product warranties as well, but these are automatically applied if the installation is done by an installer in their certified network at no cost to you; thus, these are reflected in the product warranty score.

While we don't specifically include the claim process in our scoring system, we think it's important for you to understand!

Typically, you'll file your warranty claim through your installer–but what happens if they go out of business? We contacted all nine solar panel companies to understand if it's easy to contact someone if necessary.

A solar system is a long-term investment: Typically, they last 25 to 30 years! And while solar panels generally need very little upkeep and rarely break, a strong warranty can give you peace of mind when you go solar. What's the best way to make your solar system last? Choose an excellent installer! On the EnergySage Marketplace, you'll receive up to seven quotes from our network of vetted professional installers, offering equipment with some of the best warranties. If you're looking for a specific panel brand, make a note in your EnergySage profile. 

If you represent a solar panel company and don't see your company's warranty included in this article, please contact [email protected].