When it comes to installing a renewable energy system in your own home, you are going to make sure that the juice is worth the squeeze.

Luckily, solar panels are one thing you can buy and rely on for decades to come – with most companies guaranteeing them for 25 years. We offer 30..

If a company is prepared to guarantee something for 25 years you know it will certainly last longer than that. In fact, quality solar panels will still be functioning at 80% of their initial efficiency a quarter of a century after they have been installed.

After 25 years, a 405 watt panel will generate 324 watts – not many other appliances offer that kind of longevity.  Plus, as the panels are by far the cheapest part of any solar system, you can always add a couple more to make up for the loss at a later date – if you have the capacity on your inverter. 

Although your panels will have lost some of their efficiency after 25 years, they will keep going for twice as long as that with degradation occurring at just 0.5% a year.

Your payback time on a Solar Fast system is around 9 – 11 years – so those panels are pure profit for 3/5th of their warranty.

Solar Panel Performance and Product Warranty

All panels will come with a warranty and some will come with two – a performance warranty and a product warranty.

Performance Warranty

This is the promise that the panel will generate electricity for a certain period of time. 

As this is based on the fact silicon cells degrade at 0.5% per year, it’s an easy promise to make. 

Look for brands that will give you a guarantee of at least 90% yield after 10 years and 80% after 25 years. 

Some companies, like Solar Fast, will stretch that to 30 years as panel tech is advancing every year.

Product Warranty

This is generally a standard warranty that ensures the panel is fit for purpose. 

It usually covers manufacturing defects, environmental issues, premature wear and tear and any other problems caused by a faulty build. 

The product warranty typically lasts for 25 years (but we offer 30). Always ask your fitter about extended warranties too – if may be worth a few extra pounds for that piece of mind.

What affects the lifespan of Solar Panels?

Solar Panels can be affected quite badly by high temperatures so ventilation, or at least air circulation,  is extremely important for keeping the panels cool. This is one of the reasons rooftop installations are such a good idea.

However, the first thing you can do to ensure your panels get the best start in life is to choose a fully qualified, professional fitter. 

Check out their reviews, see if you can speak to a previous customer and always make sure they are accredited with industry bodies like MCS, NAPIT and HIES.

High temperatures

If the sun is splitting the trees and cracking flagstones, you can bet your bottom dollar it’s having an effect on your solar panels. The more sun there is, the harder the cells are working and the quicker they will degrade.

However, in the UK, this is not a massive problem!

The temperate weather in the UK is just about perfect for both protecting and prolonging the lifespan of your solar panels. Most solar panels installed in the UK are still functioning at 95% even after 20 years. So, the British weather is perfect if you are looking to install a PV system in your home.

Pitch of install

Not something one would immediately consider affecting the lifespan of your solar panels, but the lower the angle of your install the more chance there is of damage from debris, wildlife and water ingress.

A panel that is installed on a flat roof, or outside the recommended angles of 20% – 50%, is more likely to collect water on the glass surface. 

This water will eventually make its way into the casing and damage the cells within.

String Problems

Solar Panels are connected to the inverter in what are called strings.

This means a number of panels are connected together to create one input into the inverter. 

If there is a badly performing panel in that string, not only will it drag the performance of the other panels down, it will start to absorb current from the panels that are working correctly. 

This will start to cause the cells to heat up and that will, ultimately, damage them

How to make solar panels last longer?

Solar panel maintenance

The truth is, solar panels need very little maintenance at all.

Solar panels have no moving parts, so you don’t get the usual wear and tear that something like a boiler or car engine would have. You don’t need to have your panels serviced and you don’t need to have bits replaced so unless there is an accident of some kind, your panels will continue to work for decades.

Monitor your system

Any problems in the efficiency of your system will be flagged up with a simple test of the system.

The simplest test is to just check the lights on the inverter during the day. When the system is running perfectly the light on the front of your inverter will be green. If the light has changed to either orange or red, then there is a problem in the system.

If this is the case it’s best to call the manufacturer, or a qualified professional, to perform a more in depth test and isolate the problem before it affects any other part of the system. We suggest checking the inverter every day.

Learn more about solar monitoring apps.


As mentioned previously, dust and dirt can affect the efficiency of your solar panels – either by blocking the sun’s rays or by scratching the surface of the panel.

Luckily, rain is very common in this green and pleasant land of ours so panels are often washed down automatically by the weather.

However, more stubborn soiling can be caused by passing birds and even sap from nearby trees. If this is the case then the panels need to be cleaned either by yourself or hiring a professional cleaner.

If you are doing the cleaning yourself then ensure you don’t use any abrasive chemicals or hard brushes as the idea is to clean the panels without scratching or damaging them.

Learn more about cleaning your solar panels.

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