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
Product Warranty (Manufacturer)
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
Most tier-one manufacturers now offer 25-year product warranties. Some budget panels still offer 10-12 years. Check before you buy.
Performance Guarantee (Manufacturer)
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
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).
Workmanship Warranty (Installer)
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
Standard workmanship warranties range from 2 to 10 years. Some installers now offer extended workmanship cover — for example, OVO Solar & Heating offers a 10-year workmanship warranty on all installations, covering the full installation quality for a decade.
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.
OVO Solar & Heating: 10-Year Workmanship Warranty
OVO backs every solar installation with a 10-year workmanship warranty — five times the industry minimum. Their certified engineers handle everything from survey to commissioning, and the warranty covers the full quality of the installation for a decade. As a recognised UK energy brand, OVO provides the kind of long-term reassurance that smaller installers often can't match.
Read more about OVO's workmanship warranty →
Get a Quote from OVO Solar →Affiliate link — we may earn a commission at no extra cost to you.
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.
Inverter Warranty Comparison
MCS Certification and Your Warranty
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, Warm Homes Plan)
- Minimum workmanship warranty standards enforced
- Consumer code of practice and complaints procedure
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 — OVO Solar & Heating offers this as 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.
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
Get Quotes from Warranty-Backed Installers
Connect with MCS-certified solar installers who offer strong workmanship warranties. Free, no-obligation quotes.
Up to 3 MCS-certified installers. No obligation quotes.
Related Guides
Solar Panel Costs
Full cost breakdown by system size, plus additional costs like inverter replacement and battery storage.
See costs →Solar Panels Guide
How solar panels work, panel types, and the complete installation process from survey to registration.
Read guide →Solar Panel Grants
Available funding including 0% VAT, the Warm Homes Plan, and the Smart Export Guarantee.
Check grants →Battery Storage
Store surplus solar energy for evening use. Battery warranties explained and costs compared.
Read guide →Heat Pump Costs
Compare solar with heat pumps. The £7,500 BUS grant makes heat pumps worth considering alongside solar.
Compare costs →Boiler Upgrade Scheme
£7,500 government grant for heat pump installation. MCS certification required — same standards as solar.
Check eligibility →Invest with Confidence
Get quotes from MCS-certified installers with strong warranty cover. Your solar system should last 25 years — make sure the protection does too.
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