Solar Panels

How Long Do Solar Panels Last? & What to Do When They Die

By:Michael Johns

lifecycle of solar panel

What do solar panels and Gen-Z have in common? Well, they’ll both still be kicking around your house after 25 years.

While one might be an expensive inconvenience, the other is an investment that keeps putting money in your pocket the longer you have it.

I’ll leave you to work out which is which…

The point I am getting at is that solar panels last a long time, decades in fact!

And when investing in a solar array installation it is important to know how long it will last to fully understand it as an asset.

You see, once the initial investment is paid off in energy bill savings, it’s completely free electricity from then on.

That means more money in your back pocket, plus you’ll be doing the environment a favor too.

How Long Do Solar Panels Last?

A solar panel should last for at least 25 years. In fact, a good manufacturer will provide a 25 year power output warranty. That means you can be safe in the knowledge that the equipment will deliver a certain amount of electricity for over 2 decades.

Even more impressively, a solar panel won’t just stop working after this time period, it will keep delivering energy for many years to come. Solar panels have even been estimated to stay operational for over 40 years.

Worn out solar panels
Work out solar panels

Solar Panels Degrade Over Time

Despite this incredible lifespan, solar panels do degrade slowly over time.

What does this mean? Well, it will lose a little performance each year. So the solar cells won’t deliver the same efficiency after 20 years as they did when brand new. 

You will notice this information included in a solar power output warranty which often guarantees a ‘minimum performance’ which reflects the age. Usually, this is something like ‘90% output after 10 years and 80% output after 25 years.

solar panel degradation rate

Based on this warranty information, you should expect a solar panel to degrade no quicker than 1% per year. (10% every 10 years).

Research on Photovoltaic Degradation Rates by the National Renewable Energy Laboratory (NREL) in 2012 confirms this data. It concluded that on average solar panels degrade at 0.8% per year. It goes on to say that “78% of all data, reported a degradation rate of <1%/year”.

Knowing this data we can use it to more closely estimate the efficiency of a solar panel based on age. Simply, start with 100% and subtract 1% for every year. 

So even after 30 years your equipment will still be delivering 70% of its original performance. (And hopefully, the kids will be gone by 30 so your electricity usage will be lower…)

Factors in Solar Panel Degradation

So why do solar cells degrade over time? Most of it comes down to the course of its operation and being exposed to variable weather.

While solar panels are built to be completely waterproof and weatherproof they are not immune to the effects of weather over time. Afterall, they are mounted on exposed rooftops! Hot and cold weather can cause hardening and cracking of the silicon crystals. This is because it is impossible to stop components expanding and contracting during thermal cycles. For example, when it’s cold objects contract, and when it gets hot they expand. In variable climates, this regular change takes its toll and can lead to microcracks across the solar cells. 

cold solar panels in snow

In addition, wind or heavy snow can cause flexing of a solar panel. This dynamic mechanical load can also lead to degradation.

Quite often, these microcracks are invisible to the human eye. But many people start to see browning or ‘snail trials’ when microcracks form and allow moisture into the cells. This doesn’t mean your solar panel is losing a lot of performance but it is a sure sign of slow degradation.

It’s important to point out here that with a high-quality installation, these effects should be minimal and won’t be noticeable over the short term. It does however add up slowly over the decades to reduce performance.

Light Degradation

Manufacturers have been able to minimize the damage done by sunlight to solar equipment. That’s key to a long life, as you don’t want the sun to be doing unnecessary damage to the equipment. Afterall, they are designed to do one thing, absorb sunlight. Modern panels use UV protective glass to keep out the most damaging rays. 

That being said, the sun will cause a little degradation, especially in a brand new solar cell first exposed to sunlight. This is called Light Induced Degradation (LID) which occurs in the first few hours of exposure. Thankfully, this problem disappears quickly and doesn’t cause more than 1-3% of initial degradation. 

4 Tips to Make Solar Panels Last Longer

It’s impossible to completely eliminate the slow degradation of solar panels but there are certain things you can do to not make the problem worse. Like anything, proper care and usage will extend the equipment life by years. Plus you can help to avoid catastrophic damage.

The good news is that they are incredibly strong and durable meaning normal weather such as wind, rain, snow, and even hail won’t directly cause damage. In fact, solar panels are hail-proof with studies of 50,000 solar panels showing a risk of hail damage to be 0.05%.

So you don’t need to worry about weather, but what else can be done to make solar panels last longer?

Reputable Installer

A reputable solar installer

It’s not worth trying to save a few quid on the initial installation only to be left with a poor job or low quality equipment. The biggest factor in unnecessary degradation is cheap incorrectly installed equipment.

A great installer will be using quality components and equipment, plus will make sure everything is completely safe. That means correct strength and waterproof mountings. You don’t want a cowboy damaging your roof either! Adding to this, they should give you a robust warranty with around 10 years cover for components and 25 years power output.

Regular Maintenance

It is wise to have a professional check over your system every once in a while. You find it hard to spot any defects yourself, especially if the system is up high on a rooftop. Regular maintenance will help to keep everything in good order, checking efficiency, cabling, and connections. 

Adding to this, other areas of your installation such as the solar inverter may need running repairs. In fact, the inverter is one of the most common points of failure in a solar panel system. 

Proper Cleaning

cleaning solar panels

As I always say, ‘a clean solar panel is an efficient solar panel’. My best advice is to get the face of your panels cleaned at least twice a year. Once in the spring and once in the autumn. You might need to do this more in particularly dusty areas of the world. 

You don’t want any dust, dirt, grime, leaves, or debris building up on the glass. Anything blocking sunlight hitting the solar cells will reduce performance significantly. For rooftop solar panels, use a professional with the correct equipment. Many window cleaning companies will take on the job as it is similar work.

Bird Proofing

One thing you might not think of is birds and other small animals. They love to make their home in the gap between solar panels and the roof. The added cost of bird proofing can save you money in the long run. It will help keep components like cabling working longer plus create less annoying mess around the array. Adding netting and bird spikes mean one less thing getting amongst your equipment.

What to Do With Solar Panels at the End of Their Life

Human beings are soon to be faced with the growing issue of dead solar panels. The infrastructure in dealing with old solar equipment is still developing and many installations are reaching the end of their life. 

You see, solar panels have been growing in popularity since the early 2000s. Now over 20 years later, these original systems are needing to be replaced. But what do you do with an old or broken solar panel?

Well, at the moment they are not the easiest thing to recycle. Plus as the manufacturing process becomes more efficient the use of precious metals like silver is reducing. This makes the reward for recycling the equipment less valuable.

Recycling Solar Panels

A few parts of a solar panel can be recycled such as glass and metal frames. These can be extracted from the equipment and sent for repurposing. Although, the value of these materials is very low. 

In addition, extracting the silicon semiconductor which makes up the solar cells is extremely difficult. The panel must be ripped apart and then broken down with acid to get hold of the silicon crystal and precious metals.

A Future Problem to Solve

The issue of dealing with old solar panels is yet to be perfected by the industry. The race to deal with equipment coming offline will only intensify as millions of tons of scrap starts to appear over the next decade. This increased stream of scrap solar panels should help companies create systems to solve the problem in the long run despite the current challenges of low value components.

Final Words on Solar Panel Degradation and Life Cycle

You can be confident that a solar panel will last for 25 years. An installer should guarantee at least an 80% level of power output over the course of this time. 

And remember, your equipment won’t just stop working after this, you will be able to get a few more years of life out of them.

They are easy to maintain, only requiring infrequent checks and cleaning over the years. 

Other than that, you can have them mounted on your rooftop and enjoy the amazing benefits of free and clean electricity for your home.