How Long Do Solar Panels Last?

In Summary: The Lifespan of Solar Panels

Short on time? Bookmark our guide explaining how long solar panels last for later, and read this quick summary instead…

Expect a typical solar panel’s useful lifespan to be in the region of 25 years. We say “useful” as this is the point where the decrease in efficiency (and reduction in energy savings), means a replacement is the best choice. 

The cost of replacement solar panels sits in the region of £300-£500 per panel. The variation in price is due to variables such as: the brand you choose, size (in watts) of the panels and the length of the manufacturer’s warranty. 

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There are two types of panels; monocrystalline and polycrystalline. Monocrystalline are longer lasting (but more expensive), with a 35+ year lifespan. 

And remember, before replacing solar panels, check other system components to ensure they’re not the cause of the fault. Check components such as the:

• Inverter
• Storage battery
• Junction box

Want to get quotes on a new system? Jump over to our solar panel page here. 

Got questions about replacing or upgrading your panels? Speak to our experts here. 

How Long Do Solar Panels Last?

Solar panels typically last 25 years or longer. This is the expected lifespan of solar panels based on a typical manufacturer’s warranty. 

However, this isn’t the full story. A brands’ warranty will often cover solar panels for any manufacturing faults or huge drops in efficiency during this 25 year period. 

This doesn’t mean the panels are completely useless at this point, they’re just not as efficient as when they were new.

The average solar panel works at around 20% efficiency. So if you’re running a group of panels that combined are 3kw (i.e. 10 x 300w panels), expect to generate a maximum of 600w per hour when conditions are perfect. 

A manufacturer is likely to specify a level where its efficiency level is deemed outside of tolerance, during their 25 year warranty period. 

For example, if they specify that panels under warranty will be replaced if they drop below 75% efficiency, they’d be replaced when the above 3kW system isn't able to produce more than 450w per hour. 

When To Replace Old Solar Panels

Solar panels could last 40 years, but if you’re out of warranty, when should you actually replace them?

If we take a look at a typical solar panel’s efficiency curve, we can see a loss of efficiency in the 2-3% range for year 1, and 0.7% thereafter: 

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Typically, somewhere in the 25-40 year range is the tipping point where solar panels should be replaced. At this point a new panel’s increased efficiency (and therefore, electricity bill savings) would offset the cost.

The exact year in which you should replace your panels depends on: 

• Electricity prices: the higher electricity prices are, the more you’ll save by installing new and efficient panels
• Your energy consumption: the more energy you consume, the more you’ll save

A side note here is that solar panels are a sunk cost; even working at reduced efficiency, they’re not useless. 

If you have a system that uses a micro solar panel inverter, you can simply add panels to your system, rather than replacing them. A micro inverter enables panels to be segregated, meaning a singular low efficiency panel won’t drop the efficiency of the whole system.

Solar Panel Replacement Costs

The cost to install solar panels sits in the region of £7,000-£12,000 for the average system in the UK.

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However, once you’re outside of the warranty period, you’ll be paying for individual panel replacement, rather than a full system replacement. 

Individual panels can be replaced at a cost of £300-£500 per panel. The installation cost of a single panel will depend on:

• The size (in watts) of each panel you install
• The current average labour price in your area
• Current government grants, such as the 0% VAT scheme, which means you won't pay the 20% VAT rate on solar installations

 You can contact our experts here to discuss anything related to solar panel installation. 

Or, jump over to our clickable solar panel tool to get a fixed price on-screen for your system. 

Solar Panel Warranty

Shortlisting solar panel brands, and don’t know which one to pick? 

Whilst efficiency and brand reputation are important, you should focus on the length of the manufacturer’s warranty when choosing solar panels.

A typical warranty for solar panels sits in the region of 10-25 years. The length of a warranty that a brand offers speaks to what they think of their product. 

The longer the warranty? The longer it is likely to last. 

If it doesn’t last the warranty period? The manufacturer foots the bill for a replacement!

‍It’s important to read the fine print of your solar panel warranty, as not all warranties are like-for-like.

Typically, a solar panel manufacturer will offer a warranty based on efficiency. For example, they might offer a warranty of 10-years (minimum of 90% efficiency) and a 25-year guarantee (minimum of 75% efficiency). 

In this case, panels would be replaced under warranty if they drop below 90% or 75% efficiency during their warranty period.

All of our systems come with a long parts and labour warranty. Get prices on-screen using our solar panel tool here. 

Which Type of Solar Panels Last The Longest?

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There are two main types of solar panels: 

• Monocrystalline 
• Polycrystalline

In general, we’d expect a monocrystalline solar panel to last longer than a polycrystalline. 

The typical useful lifespan of a monocrystalline solar panel is around 35-40 years, whereas a polycrystalline useful lifespan sits in the region of 25-30 years. 

That said, expect to pay more for a system that uses monocrystalline panels. 

Jump over to our pricing page for solar panels, and we’ll determine which type of panels are most suitable, and the most cost efficient for your property.

Solar Panel System Components Lifespan

If you’ve seen a drop in efficiency from your solar panel setup, it’s important to fault find and ensure it’s the panels, not other components in the system.

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Inverter Lifespan

A solar inverter converts electricity produced by solar panels from direct current (DC) to alternating current (AC). UK households use AC, so without an inverter, electricity produced by solar panels wouldn’t be usable. 

The typical lifespan of a solar inverter is around 10 years, around half that of a solar panel system. So, before you replace your solar panels, have an MCS solar panel engineer check your inverter for faults. 

Solar Storage Battery Lifespan

A solar storage battery enables households to store any excess electricity produced by their panels. 

Solar panels produce most of their electricity between 10am-4pm, whereas most households consume the majority of their electricity in the evenings. 

A storage battery ensures you don’t need to pay for electricity by buying it from energy suppliers during times of high consumption.

Like inverters, a solar storage battery is likely to last roughly 10 years. A MCS installer will be able to check your battery to ensure it’s storing and distributing electricity correctly.

Junction Box Lifespan

Another component worth checking before replacing solar panels is the junction box. 

Typically, any faults here are limited to wiring that get hot spots and eventually fail. 

The average lifespan of a solar panel junction box is around 25 years (similar to that of the solar panels themselves).

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