Solar Panel Warranties Explained

Information notice

This guide compiles information from manufacturer specifications, MCS standards, and installer terms. We are an independent information service, not solar installers. Warranty terms vary between manufacturers and installers — always confirm specific terms in writing before committing.

Why Solar Warranties Matter More Than You Think

Solar panels are expected to last 25-30 years. That's a long time for something bolted to your roof, wired into your electrics, and exposed to British weather. The panels themselves rarely fail — but the installation can. Wiring degrades. Roof fixings loosen. Sealant around penetration points cracks. An inverter dies at year 11.

The warranty isn't just a piece of paper. It's the difference between a free repair and a bill for scaffolding, labour, and parts that can easily run into four figures. But "warranty" isn't a single thing — it's three separate protections, and most homeowners don't realise they're different until something goes wrong.

The Three Types of Solar Panel Warranty

Manufacturer cover

Product warranty

Covers defects in materials and manufacturing. If a panel fails due to a factory fault — cracked cells, delamination, junction box failure — the manufacturer replaces it.

What's typically covered

Manufacturing defects in panels
Cell delamination and hotspot failures
Junction box and connector faults
Frame and glass integrity

Typical duration

25 years

Most tier-one manufacturers now offer 25-year product warranties. Some budget panels still offer 10-12 years. Check before you buy.

Manufacturer cover

Performance guarantee

Guarantees your panels will still produce a minimum percentage of their rated output after a specified number of years. All solar panels degrade slightly over time — this guarantee puts a floor under that degradation.

How it works

Panels lose roughly 0.5–0.7% output per year
Guarantee promises minimum 80–85% output at 25 years
If output drops below the guarantee, the manufacturer must repair, replace, or compensate

What to look for

80–85%

Minimum guaranteed output at 25 years. Better panels guarantee 85%+. Some premium manufacturers offer linear degradation guarantees (guaranteed output at each year, not just year 25).

Installer cover

Workmanship warranty

This is the one most people overlook — and the one most likely to matter. It covers the quality of the installation itself: the wiring, the roof mountings, the sealant around penetration points, the electrical connections. If your roof leaks because the installer didn't seal properly, or wiring fails because it wasn't routed correctly, this is the warranty that pays.

What's typically covered

Roof penetration sealing and waterproofing
Mounting rail and bracket integrity
Electrical wiring and connections
Inverter mounting and configuration

Typical duration

2–10 years

Standard workmanship warranties range from 2 to 10 years, and some installers now offer 10 years as standard.

Why this matters

Why workmanship cover matters most in the early years

Panels rarely fail. Installations sometimes do. The most common issues — roof leaks, loose connections, wiring faults — typically appear within the first few years. A short workmanship warranty (2 years) may expire before problems surface. Longer cover (5-10 years) gives genuine protection through the period when installation faults are most likely to appear.

Solar Warranty Comparison at a Glance

Warranty type	Provided by	Typical duration	What it covers	What to check
Product warranty	Panel manufacturer	25 years	Manufacturing defects, material failures	Is the manufacturer established? Will they exist in 25 years?
Performance guarantee	Panel manufacturer	25 years	Output degradation below guaranteed minimum	Is it linear (yearly) or just a year-25 floor?
Workmanship warranty	Installer	2–10 years	Installation quality: wiring, mounting, sealing	How long? Is it insurance-backed?
Inverter warranty	Inverter manufacturer	5–25 years	Inverter failure or performance issues	String (5-12yr) vs microinverter (up to 25yr)?

Inverter Warranties: The Component Most Likely to Fail

While panels can last 25-30 years with minimal issues, inverters have a shorter lifespan. According to industry data, string inverters typically last 10-15 years — meaning you'll likely need at least one replacement during the life of your solar system.

Replacement costs range from £500 to £1,500 depending on the type and capacity. This is a known cost that should be factored into your payback calculations from the start.

Comparison

Inverter warranty comparison

String inverter

Single unit, wall-mounted

5–12 years

£500–£1,500 to replace

Microinverter

One per panel, roof-mounted

Up to 25 years

Higher upfront cost

Hybrid inverter

Handles solar + battery

5–10 years

Check battery compatibility

MCS Certification and Your Warranty

The standard

Why MCS matters

The Microgeneration Certification Scheme (MCS) is the UK quality standard for renewable energy installations. Using an MCS-certified installer isn't just about quality — it unlocks financial benefits that non-MCS installations can't access.

Required for Smart Export Guarantee eligibility (get paid for surplus)
Required for government grants (Boiler Upgrade Scheme for heat pumps and biomass boilers; Warm Homes: Local Grant, England only)
Minimum workmanship warranty standards enforced
Consumer code of practice and complaints procedure

The risk

The risk of non-MCS installation

Non-MCS installers may offer lower prices, but the hidden costs can be significant:

No Smart Export Guarantee payments (loss of income for 25 years)
No access to government grants (BUS worth £7,500)
No guaranteed minimum workmanship standard
No consumer protection complaints route via MCS
May affect home insurance and property valuation

Seven Questions to Ask Before You Sign

What is your workmanship warranty period?

Look for 5 years minimum. 10 years is the gold standard. Anything less than 2 years is a red flag.

Is your workmanship warranty insurance-backed?

If the installer goes out of business, an insurance-backed warranty means another company will honour the cover. Without this, the warranty dies with the company.

Which panel manufacturer and model are you using?

Research the manufacturer. Established brands (25+ years in business) are more likely to honour warranties decades from now. Check the specific product and performance warranty terms.

Is the performance guarantee linear or end-of-term?

Linear guarantees (e.g. minimum 90% at year 10, 85% at year 25) are stronger than a single year-25 floor.

What type of inverter, and what's the warranty?

String inverters (5-12 years) will need replacing. Microinverters (up to 25 years) cost more but may not. Factor this into total cost.

Are you MCS-certified?

Non-negotiable. No MCS certification means no Smart Export Guarantee, no government grants, and no guaranteed installation standards.

Will you provide all warranty documents in writing before I pay?

Verbal promises mean nothing. Get the product warranty, performance guarantee, workmanship warranty, and inverter warranty documented before you commit.

Insurance-Backed Warranties: Why They Matter

A workmanship warranty is only as strong as the company behind it. The solar installation industry has seen companies come and go — and when an installer closes, their warranty closes with them. Unless it's insurance-backed.

An insurance-backed warranty means a third-party insurer will honour the workmanship cover even if the installation company ceases trading. Given that your solar system is expected to last 25+ years, and the average UK business lifespan is significantly shorter, this protection is worth asking about.

Checklist

What to look for

Named insurance provider (not just "insurance-backed")
Certificate issued directly to you (not held by the installer)
Clear claims process documented
Transferable if you sell the property

Common questions

What warranties should I get with solar panel installation?▾

A solar panel installation should come with three types of warranty: a product warranty from the panel manufacturer (typically 25 years), a performance guarantee ensuring minimum output over time (typically 80-85% output at 25 years), and a workmanship warranty from the installer covering the quality of the installation itself (typically 2-10 years, with some installers offering longer).

What is a workmanship warranty for solar panels?▾

A workmanship warranty covers the quality of the installation itself, not the panels or inverter. If issues arise due to how the system was installed — wiring faults, roof penetration leaks, mounting failures — the installer repairs them at no cost during the warranty period. Standard workmanship warranties are 2-10 years, though some installers offer longer cover.

How long do solar panel warranties last in the UK?▾

Product warranties on solar panels typically last 25 years. Performance guarantees usually promise at least 80-85% of original output at 25 years. Inverter warranties range from 5-12 years for string inverters and up to 25 years for microinverters. Workmanship warranties from installers vary from 2 to 10 years, with some providers offering extended cover.

Does MCS certification affect my solar panel warranty?▾

Yes. MCS-certified installers must provide a minimum workmanship warranty and adhere to installation standards. MCS certification is also a requirement for Smart Export Guarantee eligibility and access to government grants like the Boiler Upgrade Scheme (for heat pumps and biomass boilers, not solar). Using a non-MCS installer may void certain warranties and disqualify you from financial incentives.

Get quotes from warranty-backed installers

Connect with MCS-certified solar installers who offer strong workmanship warranties. Free, no-obligation quotes.

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