Solar panel warranties: What to know

The number of years the warranty covers the integrity of the equipment.

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

Does the manufacturer’s warranty cover the work needed for diagnostics, repairs, or replacements? Is it up to a certain dollar amount?

Does the warranty cover the cost of sending out any components that must be diagnosed, fixed, or replaced?

Can you extend your product warranty by paying more?

Does the manufacturer offer a power warranty out to 30 years or more (either automatically or at an additional cost)?

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

Does the warranty extend to the system’s inverters?

Does the warranty cover the system's racking equipment?

This sets the number of years the manufacturer is guaranteeing a certain minimum level of performance. Frankly, there's not a ton of variability across the industry; nine times out of 10, your panels will come with a 25-year power performance warranty. However, as technology advances, manufacturers are starting to offer longer warranty periods. Silfab, for example, is now offering 30 years of coverage, while Maxeon's power warranty spans a whopping four decades.

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.

A few things to look out for when comparing degradation rates:

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

• After year one, manufacturers typically ensure that power output won't fall by more than 0.5 - 0.7% annually for the length of the warranty term (or, if you're Maxeon, 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.

• A warrantied degradation rate, like the 0.5-0.7% rate we mentioned above, differs from what you'll experience in real-life conditions. All solar panels undergo strict testing to evaluate performance, and when manufacturers establish their power warranties, they stick to conservative numbers they feel confident in.

Most manufacturers don’t reimburse for the labor associated with replacements or repairs of their products (and if they do, the costs are only covered up to a certain amount). However, this usually isn't an issue since many local installation companies will cover maintenance and repair costs within their own warranty agreement.

A small number of solar panel manufacturers offer an extra safeguard through additional workmanship warranty coverage. It's typically only an option if you work with specific installers within a manufacturer's certified network.

This is an aspect 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 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.

If someone buys your home (and, therefore, your solar panel system), does the warranty transfer over to the new owner?

Do you need to work with one of the manufacturer's certified installers to take advantage of the warranty? If someone outside their network repairs your system, does that void your warranty claim? And can you still take advantage of the warranty if you do a DIY installation?

 Live on a beachfront property? If so, confirm that this won't void your warranty. Saltwater corrodes solar equipment quicker, so some panel manufacturers will void a warranty if their products are within a certain distance of saltwater environments.

Most solar panel manufacturers will not cover any damage caused by extreme weather events outside their control, such as hurricanes, floods, earthquakes, etc. Fortunately, solar panels are durable and can withstand most storms without the added protection. Should storm-related damage occur, most homeowner insurance policies cover solar panels.

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.