If you’ve spent any time looking at our financial projections for solar in your state, you may have noticed that we look at the energy bill savings you can expect for 25 years after installation. That 25-year timeline wasn’t just plucked out of thin air: it’s the length of time over which most manufacturers guarantee their solar panels will produce electricity.
But that 25-year production warranty is just the beginning. Unlike most big appliance purchases, a solar installation will have up to 3 or 4 various warranties and guarantees each covering something different and working in concert with the others to protect you and your home at the time of installation and for years after.
And although the warranties are written for 25 years, modern solar panels will probably keep working for a decade or two longer than that expiration date. Read on to discover the world of solar warranties!
What kinds of warranties cover solar installations?
A solar installation is made up of solar modules (aka panels), attached to your roof with mounts and racking, wired together with an inverter that converts direct current from the panels to alternating current for your home or the grid.
The manufacturers of solar panels offer two kinds of warranties: a warranty that the panels will be free of defects in materials and workmanship; and a long-term power production warranty. The makers of solar inverters provide warranties for materials and workmanship in their products, too.
Finally, the solar installer will offer a warranty that their work will cause no damage or roof leaks. Solar racks and mounts also come with warranties, but claims are usually handled by the installer. In fact, if you have a warranty claim for any part of your system, you’ll likely go through the installer instead of worrying about contacting the manufacturer.
What does the solar panel materials and workmanship warranty cover?
Solar panels are one of the simplest ways to generate electricity. With no moving parts, all they are is a few layers of photovoltaic and conductive materials encased in extremely durable glass and surrounded by a metal frame.
There’s not much that can break in a solar panel, and each each of the components goes through multiple tests during the assembly process, so once the finished panel rolls off the assembly line it’s ready to go up on a roof and start kicking out kilowatts.
Still, sometimes there’s a stray corner that isn’t properly sealed or a slightly-warped frame, but when these problems occur, they usually happen really soon after installation. So the materials and workmanship warranty covers these things, and most solar manufacturers have materials and workmanship warranties of 10 to 20 years.
Here’s an example from U.S. manufacturer SolarWorld:
Which solar panel manufacturer offers the best materials and workmanship warranty?
|Company||Years of Coverage||Start Date|
|SunPower X- and E-Series||25||Earlier of date of interconnection or 6 months following delivery|
|Panasonic||25||Date of purchase (15 years if not registered with Panasonic within 60 days of purchase)|
|SolarWorld||20||Date of sale to original owner|
|LG Solar||12||Date of purchase|
|Kyocera||10||Date of sale to original owner|
|REC Solar||10||Date of sale to original owner, not to exceed 10.5 years from date of production|
|Canadian Solar||10||Earlier of date of installation or 90 days after delivery|
|Canadian Solar - Dymond modules||10||Earlier of date of installation or 90 days after delivery|
|Yingli Solar||10||Earlier of date of purchase or 1 year after production|
|Trina Solar Monocrystalline||10||Earlier of date of delivery or 12 months after production|
|Trina Solar Polycrystalline||10||Earlier of date of delivery or 12 months after production|
What does the power production warranty cover?
Here’s where we start getting into the fun! Solar panel production warranties are only in effect as long as the panel is still functioning. In the very rare case that a panel fails for a reason that’s not covered by the materials and workmanship warranty, the power production waranty is null and void.
In the very likely case that the panel is perfectly functional for the lifetime, a power production warranty states that the panel will put out a certain number of watts at a given time. For example, the SolarWorld module warranty states that upon installation, the panel will put out 97% of it’s “effective output,” which is also called “output under Performance Test Conditions” (i.e., real world output under full sun).
Then, SolarWorld says its panels won’t decline by more than 0.7% annually so that “as of the end of the 25th year after purchase, an actual output of at least 80.2% of effective output will be achieved.”
Here’s the SolarWorld production warranty (they call it a “Performance Guarantee”):
Annual vs linear solar production warranties
The two kinds of warranty offered by solar manufacturers dictate the points in time at which the warranty is in effect. An annual production warranty generally states that the panels will still produce a certain % of their rated power by the end of each year after installation. So if the production rate dips below the end-of-year target, the warranty should kick in and the manufacturer should repair the panel.
In the case of a linear rate of decrease, the panels are guaranteed to produce a certain percentage of their rating on day 1, and not to dip below a pro-rated annual rate based on the day of the year. So for example, if the production guarantee decreases by a linear rate of 0.7% per year, that would mean the decrease could not exceed 0.35% by the middle of the year. In the case of an annual warranty, on the other hand the decrease could be as much as 0.7% on January 1st, and as long as it didn’t sip below that, it still wouldn’t trigger the warranty protections.
Here’s how the differences look on a chart:
Which solar panel manufacturer offers the best production warranty?
|Company||Starting production guarantee||% decrease/yr||Calculation||#of Years|
|SunPower X- and E-Series||98%||0.25%||annual||25|
|Canadian Solar - Dymond modules||97.5%||0.5%||annual||30|
|LG Solar||95% (at the end of 5 years after purchase)||0.40%||annual||25|
|Trina Solar Monocrystalline||97%||0.68%||annual||25|
|Trina Solar Polycrystalline||97.5%||0.7%||annual||25|
What does the inverter warranty cover?
Inverters also have zero moving parts, unless you count the breaker switches that might be included to disconnect parts of the system from the inverter. But over time, capacitors, computer components and other materials can fail with age and use. Most inverter manufacturers offer materials and workmanship warranties of 10 years that cover any failures of those components before that time.
It’s important to note there are two main varieties of inverter you’ll come across in residential solar installations. The first is called a “grid-tie” inverter, in that it is the piece of equipment that receives DC electricity from the solar panels, and converts it to AC electricity that can be used in your home or sent to the grid. The second is called a microinverter, which is a small box that attaches to the backside of a solar module and does the same job.
Because microinverters are smaller, simpler, and designed to withstand the outside environment, warranties tend to be longer.
What’s not covered by inverter warranties?
Of course this varies by company, but here’s an idea, from SMA’s Sunny Boy inverter warranty (PDF):
- Transport damage
- Incorrect installation or commissioning
- Failure to observe the user manual, maintenance requirements and intervals
- Modifications, changes or attempted repairs
- Incorrect use or inappropriate operation
- Insufficient ventilation of the device
- Failure to observe the applicable safety regulations
- Force majeure (e.g. lightning, overvoltage, storm, fire)
- Cosmetic defects which do not directly influence energy production, or degrade form, fit, function
Which inverter manufacturer offers the best warranty?
|Company||Type||# of Years||Start Date|
|SunPower||MicroInverter||25||Date of purchase|
|Enphase||MicroInverter||25||Earlier of date of install or 4 months following delivery|
|SolarEdge||Grid-Tie||12||Earlier of date of install or 4 months following delivery|
|SunPower||Grid-Tie||10||Date of purchase|
|SMA (SunnyBoy)||Grid-Tie||5-10||Date of first commisioning|
What does the installation warranty cover?
When a solar installer comes to your house, they’re gonna have a few members of their crew crawling all over your roof and screwing giant bolts through your rafters. Luckily, the solar industry has developed all kinds of great tools and equipment that will keep your roof intact, watertight, and looking great throughout the lifespan of your solar installation.
But sometimes things happen, and that’s when you need the peace of mind that comes with a robust warranty. A good installation warranty will cover both “roof penetrations” and damage to your roof by the installation crew. For example, here’s SolarCity’s Roof Warranty:
When we penetrate your roof during a System installation we will warrant roof damage we cause due to our roof penetrations. This roof warranty will run the longer of (A) one (1) year following the completion of the System installation; and (B) the length of any existing installation warranty or new home builder performance standard for your roof (the “Roof Warranty Period”).
That last bit is important; you want to make sure your solar installer isn’t voiding any existing roof warranty, or if they are, that they’re willing to supplant it with their own coverage. As you read above, SolarCity/Tesla covers damage to your roof in their warranty. Sunrun also claims to offer a roof warranty as part of their protection package. Vivint solar does not mention a roof warranty anywhere on their site.
How you can trust a solar panel warranty
One of the things people are most worried about when it comes to solar warranties is “what happens if the installer or manufacturer goes out of business?” That’s a valid concern given that the solar industry has exploded in recent years and, in the U.S. especially, has seen a few high-profile bankruptcies of solar companies.
The good news is, if a solar manufacturer wants its panels to be used in large-scale installations, it has to provide investors in those installations with convincing evidence that its warranty will be honored. The way that is done is by purchasing warranty insurance supplied by an underwriter.
One such underwriter is PowerGuard, which provides insurance to manufacturers of some of the world’s most popular solar panels. PowerGuard and others insure the solar warranties for companies like Trina Solar, Yingli, Canadian Solar, and more.
The bottom line for solar warranties
Which manufacturer has the best solar panel warranty? If you couldn’t tell from the tables above, the winner is SunPower, which offers a 25-year materials and workmanship warranty and guarantees that their panels’ output will decrease by no more than 8% total over 25 years. That 8% guarantee is twice as good as their nearest competitor.
When you’re getting solar installed, make sure you understand the warranties offered by your installer. If you choose to own your system, you’ll likely have warranty paperwork from the manufacturers of your panels and inverters as well as a workmanship warranty on the installation. If you choose third-party ownership, your installed will likely be the sole source of the warranties, supplanting the OEM warranties with their own materials warranty and power production guarantee.
Always make sure you get the manufacturer name and model numbers of any equipment during the quote process. To get help from solar experts near you, simply fill out our quote request form, and take the first step of your solar journey!