Solar Panel Warranty UK: What Your Warranty Covers and How Long It Lasts

When you invest thousands of pounds in a solar panel system, you want to know it’s protected. A solar panel warranty isn’t just a piece of paper, it’s the difference between a repair that costs you nothing and one that costs you hundreds. The best solar panel systems come with three separate warranties covering the panels themselves, their long-term performance, and the quality of the installation work.

Understanding what each warranty covers, how long it lasts, and what could void it is essential before you sign anything. This guide explains everything UK homeowners need to know.

Key Takeaways

• A complete solar installation should come with three warranties: product (25 years), performance (25 years linear), and workmanship (minimum 2 years from MCS installers, ideally 10)
• Inverter warranties are typically shorter, 5 to 12 years, and often need extending separately
• Battery warranties are usually 10 years or a cycle-count guarantee (e.g. 6,000 cycles), whichever comes first
• Only MCS-certified installers can offer an Insurance-Backed Guarantee, which protects you if the installer goes out of business
• Panel warranties require panels to have been installed correctly, a non-MCS installation may void the manufacturer warranty
• Warranties do not cover damage from storms, vandalism, or bird strikes, that’s what home insurance is for

The Three Types of Solar Panel Warranty

There are three distinct warranties you should receive when a solar PV system is installed on a UK home. Confusing them is easy, but they cover very different things.

Product Warranty (Also Called the Materials Warranty)

The product warranty is provided by the panel manufacturer. It covers defects in the materials or workmanship of the panels themselves, things like delamination, frame corrosion, cell cracking under normal conditions, or junction box failures.

A standard product warranty in 2026 runs for 25 years, though premium brands such as REC, Panasonic, and SunPower offer 25 to 30 years. Budget brands sometimes offer shorter terms, 10 or 15 years, which is a red flag worth noting when comparing quotes.

Under a product warranty claim, the manufacturer will either repair or replace the faulty panel. You won’t typically get compensation for lost generation during the period of the fault.

Performance Warranty (Linear Degradation Guarantee)

All solar panels lose a small amount of output each year as the cells age. The performance warranty, sometimes called the linear degradation warranty, guarantees that your panels won’t degrade faster than a stated rate.

The industry standard in 2026 is a guarantee that panels will produce at least 80% of their original rated output after 25 years. Premium TOPCon and HJT panels often guarantee 87% or even 90% after 25 years, because they degrade more slowly.

A typical degradation schedule looks like this: no more than 2% loss in year one, then no more than 0.45% per year for years two through twenty-five. If your panels fall below these thresholds, the manufacturer owes you compensation, either replacement panels or a cash settlement based on lost generation.

Workmanship Warranty (Installer Warranty)

The workmanship warranty covers the quality of the installation itself. This is provided by your installer, not the manufacturer, and it covers things like poor roof fixings, incorrectly sealed cable penetrations, faulty wiring connections, or anything else that results from how the job was done rather than how the panels perform.

Under MCS (Microgeneration Certification Scheme) rules, certified installers must offer a minimum two-year workmanship warranty on every installation.outinely offer 5 to 10 years, and some offer 10 years as standard. When you’re comparing quotes, always ask what workmanship warranty is included.

Inverter Warranty

Your inverter converts the DC electricity from your panels into AC electricity your home can use. It’s the hardest-working component in the system and the most likely to need replacing during the life of your panels.

Standard string inverter warranties run for 5 to 12 years, depending on the brand. Fronius and SMA typically offer 5 to 10 years extendable. SolarEdge offers a 12-year warranty extendable to 25 years (for an additional fee). Enphase microinverters offer 25 years as standard, which is one of their key selling points.

The gap between a 10-year inverter warranty and a 25-year panel warranty matters. If your inverter isn’t covered past year 10, you should budget for a replacement sometime between years 12 and 15, typically £700 to £1,500 for a standard string inverter, or more for a hybrid model.

Extending your inverter warranty at the point of installation is usually far cheaper than buying an extended warranty later.

Battery Warranty

If your system includes a battery, the warranty structure is slightly different. Battery warranties are typically 10 years in duration and often include a cycle count guarantee, for example, “10 yearsor 6,000 full charge/discharge cycles, whichever comes first.”

LiFePO4 (lithium iron phosphate) batteries, which dominate the UK market in 2026, typically guarantee 80% remaining capacity at end of warranty. NMC (nickel manganese cobalt) batteries may degrade faster under heavy daily cycling.

Lead-acid batteries, still used in some off-grid systems, typically carry only a 2 to 5 year warranty and don’t suit daily cycling.

Brands like GivEnergy, Fox ESS, Tesla Powerwall 3, and Solis/PYLONTECH all offer 10-year battery warranties in 2026. Check whether the warranty is based purely on years or has a cycle limit that could expire earlier if you charge and discharge daily.

What Solar Panel Warranties Do NOT Cover

Warranties are often more limited than homeowners expect. Common exclusions across all three warranty types include:

Physical damage from external causes, storm damage, hail impact, fallen trees, bird strikes, vandalism, fire, or flooding. These are your home insurer’s responsibility, not the panel manufacturer’s.

Improper installation, if panels are installed by a non-MCS-certified installer and something goes wrong, manufacturers may refuse to honour the product or performance warranty on the grounds that the installation didn’t meet their requirements.

Unauthorised modifications, adding panels to an existing string without proper assessment, or using incompatible components, can void warranties.

Normal degradation within the guaranteed thresholds, if your panels are still producing within the warranted range, the performance warranty won’t pay out even if output has dropped.

Acts of God, extreme weather events that exceed design specifications are excluded from most warranties.

Insurance-Backed Guarantees (IBGs)

One concern UK homeowners have is what happens if their installer goes out of business. The solar industry has seen installers fold with some regularity, and without protection, a 10-year workmanship warranty becomes worthless the moment the company ceases trading.

The answer is an Insurance-Backed Guarantee (IBG). Under the Renewable Energy Consumer Code (RECC), which all MCS-certified installers must follow, every customer must be offered an IBG. The IBG is underwritten by a third-party insurer, so if your installer goes bust, the insurer covers you for the remaining term of the workmanship warranty.

IBGs are not automatic, they’re a separate product you opt into, usually at a small additional cost (around £50 to £150). But for something that protects you for up to 10 years on a £7,000 to £15,000 investment, it’s almost always worth taking.

Non-MCS installers cannot offer IBGs. This is one of the most important reasons to only use MCS-certified companies.

How to Make a Warranty Claim

For product or performance warranty claims, you’ll contact the panel manufacturer directly. You’ll need: your installer’s name and contact details, the installation date, panel model numbers and serial numbers, and a description of the fault. Most manufacturers ask for a copy of your monitoring system data or an MCS report from a qualified assessor.

For workmanship warranty claims, you contact your installer first. If they’re unresponsive or have ceased trading, you contact the IBG provider.

Keep all your documentation in one place: your MCS certificate, the installation report, warranty cards, and your IBG certificate. You’ll need them if you ever make a claim, or when you sell the property.

Solar Panel Warranty When Selling Your Home

Solar panel warranties are generally transferable to new owners when a property is sold. This can be a positive selling point. Buyers and their solicitors will want to see the original MCS certificate, the three warranty documents, and the IBG certificate.

Leased solar panel systems (where a third party owns the panels) are a different matter and can complicate a sale, this is one reason the rent-a-roofmodel has fallen out of favour in the UK. If the panels are owned outright, warranty transfer is typically straightforward.

Case Study: Warranty Claim After Inverter Failure in Yorkshire

Background

A family in North Yorkshire had a 4.2kWp solar system installed in 2026 by an MCS-certified installer. The system included a SolarEdge string inverter with a standard 12-year warranty.

Project Overview

Three years after installation, the homeowners noticed their monitoring app was showing zero generation. The inverter had stopped communicating and all output had ceased.

Implementation

The homeowners contacted their installer, who confirmed the inverter had failed. Because the installation was MCS-certified and the inverter was within its 12-year warranty period, SolarEdge arranged for a replacement unit at no charge to the homeowner. The installer fitted the replacement inverter under the workmanship warranty, with no call-out fee.

Results

The system was back generating within five days of the fault being reported. The homeowners paid nothing. Total cost without warranty cover would have been approximately £1,100 for the inverter plus £200 for labour.

Expert Insights From Our Solar Panel Installers About Warranties

One of our senior solar panel installers with over 14 years of experience in UK residential systems offers this guidance:

“The workmanship warranty is the one most homeowners overlook, but it’s arguably the most important in the first five years when installation-related issues are most likely to emerge. A two-year workmanship warranty is the legal minimum under MCS rules, but I’d always push for 10 years, and take the IBG. The panel manufacturer isn’t going to come round and look at your roof. Your installer is. Make sure they’re still around to do it.”

Frequently Asked Questions

Summing Up

A solar panel warranty is only as good as the installer who provides it and the paperwork you keep. The most important steps are to use an MCS-certified installer, take the Insurance-Backed Guarantee, and store all your warranty documents somewhere you’ll find them in a decade. With a 25-year product warranty, a 25-year performance guarantee, a 10-year workmanship warranty backed by an IBG, and an inverter warranty that covers the first decade of operation, your system should be financially protected for the years that matter most.

Updated April 2026