How Long Do Solar Panels Last?

“25-30 years” is the most common answer when you ask about the life of solar panels. Unfortunately, this number is far from reality. The idea that solar panels stop working after 25 years is a common misconception that seems rooted in the fact that 25 years is the solar industry’s standard performance guarantee period. However, your solar panels (or modules, in industry parlance) will produce energy for your home or business well beyond the scope of the warranty. In fact, many ground-mounted solar panels installed over 40 years ago are still operating today. 

Your system isn’t going to suddenly stop working just because your 25-year performance warranty expires. It simply means that the panel efficiency has decreased by what the manufacturer considers “a significant amount”. In order to properly understand the true lifespan of solar panels, we must address all the factors at play. Understanding things like solar panel degradation rate (and all the factors that affect it), local weather conditions, panel maintenance needs, and even certain positive lifespan factors all contribute to a better understanding of the probable lifespan of solar panels. 

What is Panel Degradation?

If you’ve researched solar panels, you’ve probably run into the term “panel degradation rate.” But what does that really mean? By definition, it is the reduction in solar output over time. For example, if your panel degradation rate is 0.5% (one-half of one percent), then in 20 years your system will be producing about 91% of its first-year output. However, it is important to understand that not all panel degradation rates are created equal.

A solar panel’s first-year production degrades at a different rate than the later years. This first-year rate is called the “burn-in.” Burn-in Efficiency loss is caused by the reaction of boron (which is used to dope some photovoltaic cells) and oxygen, resulting in a phenomenon called “Light-Induced Degradation” (LID). A few manufacturers, like REC, are taking steps to minimize this loss by reducing or eliminating boron in their photovoltaic cell doping processes. But even with boron eliminated, oxygen that creeps into the silicon during the melt process portion of cell wafer manufacturing can still cause first burn-in losses.

Most solar panel models have a warranted maximum first-year burn-in rate of 3%. In a December 2013 study by SERIS, the Solar energy Research Institute of Singapore, a cross-section of solar modules from different manufacturers were found to have average first-year burn-in rates of about 3%, with some modules losing as much as 4%. In stark contrast, REC Alpha series solar modules lost only 1-1/2% in the same study. REC warrants that the first-year burn-in loss for its Alpha Series modules will not exceed 2%.

Typical Service Life vs Actual Life 

The typical service life of solar panels usually correlates to the warranty expressed by each manufacturer. For one of the more premium options on the market (and our personal favorite), the REC Alpha Series, the warranted first-year performance is 98%, with a 0.25% (two-and-a-half tenths of one percent) annual degradation beyond year one –  outshining the industry standard. This means that even after 25 years of owning your solar, Alpha Series solar panels are guaranteed to still produce over 92% of nameplate efficiency. This is one big reason why the answer to, “How long do solar panels last?” is clearly beyond 25 years. 

Maximizing the Life of Your System

Although anyone who goes solar will see big savings on their electric bills, it goes without saying that you want to get the most bang for your buck when you make a big purchase like a solar power system. So when it comes to the actual life of your system, it is important to be aware of the factors that can either help or hurt in the long run. Whether it’s to reduce your utility bill or your carbon footprint, the longevity of your solar power system is the ultimate goal. Here are some things to consider that can drastically improve the life and quality of your solar investment. 

Local Weather Patterns

Just like us humans, solar panels love to soak up the sun… even if too much can cause damage (don’t forget to apply that sunscreen). In climates where surface temperatures can reach up to 150˚ F and then drop by 50-100˚ overnight, something called thermocycling can occur. Materials expanding in the heat and contracting when it cools can harm system components like cells and racking. While this drastic temperature swing isn’t common in most places, and is even less likely to occur year-round, it is important to note that even with less intense weather patterns, daily thermal expansion and contraction occur in every climate. 

On the other end of the spectrum are colder climates. While it may seem counterintuitive at first, colder temperatures actually increase solar panel efficiency. The reason is that heat reduces solar photovoltaic cell efficiency. Even so, because the warmer months typically have more sun, the amount of electricity produced in the winter isn’t necessarily greater than in the summer.

However, unlike the number of toppings on a sundae, there is such a thing as too much when it comes to snow. If you live in an area with periodic snowfall, snow accumulation on your solar panels will block sunlight and reduce energy production to zero. Solar panels covered with snow quite literally change from absorbing solar energy to reflecting it. (No, your panels aren’t enjoying that white Christmas quite as much as you are.)

The biggest tool that panels are equipped with to prevent this from happening is their pitch. Studies have found that a slope of 20 degrees or more can reduce annual energy production losses from snow cover to five percent or less, in all but the heaviest winter snow climates. If this isn’t enough for your system to keep from packing on the pounds of snow, then the best solution is to simply use a telescoping pole with a squeegee on the end to gently scrape it off, and it will continue production as usual. 

So that covers extreme heat and cold. But there are many other factors stemming from your local climate that can affect the life of your system. One of the most concerning elements your panels might have to face is hail. While almost all solar panels on the market are tested to withstand “extreme” weather conditions, these tests don’t always emulate the harsh environments that some systems may be exposed to. Manufacturers typically test their solar panels for hail resistance by firing spherical projectiles about 25 mm in diameter into the panel glass, at a velocity of about 50 mph. 25 mm is about the size of a golf ball.

If you are concerned about your solar panels being exposed to hail, it is important to reflect on your area’s historic weather patterns (how likely does it hail, and how large are the typical hailstones? If you live in an area where this is a high concern, it may be worth reconsidering your options.

Another option is to request a more intense hail evaluation test from your manufacturer. While this is still a grey  area in terms of the pricing and process of these requests, “the more that large asset owners make these hail evaluation requests, the more likely that suppliers will respond with new modules and more stringent factory hail standards.” *

Above all, the best way to ensure panel durability in the long run is to choose a trusted manufacturer from the get-go that has reliable panel testing practices. The previously mentioned REC Group goes above and beyond when putting their products to the test, with a process called “rolling reliability testing”. While most solar panels are required to meet IEC (International Electrotechnical Commission) standards, REC not only surpasses that benchmark, but doubles it. With their own lab equipped with testing technologies such as mechanical load simulators, climate chambers, and state-of-the-art hail impact testers, you can rest assured that REC’s solar panels come off the production line ready to withstand whatever mother nature may throw at them.  

Panel Maintenance 

Now, for all the Florida folks who dreadfully await those few months when the state gets draped in a sheet of yellow powder every year… let’s talk about pollen season. Allergies are at an all-time high, and you can’t touch or lean against anything that sits outside without a dangerous amount of mustard-colored dust transferring to your clothes (shout out to park benches and dark clothes in April). Fortunately, along with pollen comes rain. You know what they say: April showers bring May flowers… and also fewer panel cleanings for solar owners. Because it rains so frequently in Florida, it is suggested that you get your panels cleaned once a year – right after pollen season, and only if needed. For anywhere else, periodic rinses (just water, and a sponge or soft-bristled brush will do the trick) are good to wash away any accumulated particles. Cleaning early in the morning, when any residue on the panels has been softened by overnight dew, is best. Just make sure to never step on your panels if you decide to do this yourself.

Quality Installers Bring Reliability

One way to ensure the longevity of your system along with maximum efficiency is to exercise great care when choosing a solar installation contractor. This is one of those “you get what you pay for” instances, for a few reasons:

If you go with the cheapest installer in the area, you probably won’t get the top level of care and expertise when it comes to the installation and the service thereafter. However, if you take the time to research your options, check out the reviews and ratings of each installer in your area, and make an informed decision based on your findings, then you will benefit in more ways than one. During the installation process, if you work with a company that cuts corners and uses the cheapest materials, it will end up costing you more in the long run. You want quality hardware that is installed with care by licensed and experienced professionals. Otherwise, you will likely run into issues down the road like exposed wires, a gap between the roof and the solar that is less than 4 inches (possibly limiting solar panel ventilation and cooling, with a resulting impact on your energy production), or just really cheap panels that can’t hold up to the rigors of Florida’s climate.

The list of things that you could regret if you go with the cheapest option on the market could go on and on. General rule of thumb: if it looks and sounds too good to be true, it probably is. 

As you can see, the answer to, “how long do solar panels last” cannot be contained to just a number of years. It depends upon a multitude of things, ranging from the climate you live in, to the company you decide to go with for your installation. But don’t let all of these factors and variables overwhelm you. If you decide to go with a reputable company like PPM (contact us to learn about your options), you can rest assured that all of the factors that go into a very long service life solar power system have been fully considered. And remember: solar panels are tougher than they look. As long as you follow a few necessary steps, your panels should live a long and happy life doing what they do best – providing you with an abundant supply of good, clean energy.

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