The three warranty layers on a UK solar install
Every UK MCS-certified commercial solar PV install carries three distinct warranty layers, each providing different protection:
1. Product warranty
Covers physical defects in the modules and inverters. Standard duration: modules 12–25 years; inverters 5–12 years. If a module fails physically (broken glass without external cause, internal cell failure, junction box defect, etc.), the manufacturer repairs, replaces, or refunds under product warranty. Premium tier-1 manufacturers (LONGi, JA Solar, Trina, JinkoSolar, Canadian Solar, REC) typically carry 25-year product warranties on commercial modules in 2026.
2. Performance (output) warranty
Guarantees minimum power output over time. Industry-standard linear degradation curve: 98% in year 1, dropping ~0.5% per year to 84–87% at year 25. Premium modules guarantee 87–92% at year 25. If real-world generation falls below the guaranteed curve, the manufacturer is liable. This is where ongoing monitoring matters — without generation data, you can't prove a breach.
3. Workmanship (installation) warranty
Covers installation defects: poor cable routing causing chafing, sub-standard mounting causing weather ingress, incorrect electrical commissioning. Typically 2–10 years from the installer. Critical: if the installer ceases trading, this warranty becomes worthless — which is exactly what the Insurance-Backed Warranty exists to address.
Insurance-Backed Warranty (IWA) — why it matters
An Insurance-Backed Warranty is a third-party insurance product that takes over your workmanship warranty if the original installer goes out of business. RECC (Renewable Energy Consumer Code) and TrustMark both require certified installers to provide an IBW on every install. IWA (Independent Warranty Association) is the most widely recognised UK provider. Without an Insurance-Backed Warranty, if your installer fails, you're on your own for any installation-defect issue.
For UK farm-scale installs (typically £50,000–£400,000 capex), the workmanship warranty is materially valuable — an IBW that activates protects that value over 5–10 years. We provide IWA-backed cover on every commercial farm install as standard.
What's NOT covered by a solar panel warranty
- Lightning strike or storm damage — covered by your buildings or commercial insurance, not the module warranty
- Accidental damage during cleaning or maintenance — also buildings/commercial insurance
- Cosmetic defects that don't affect performance — explicit exclusion in most warranties
- Degradation within the guaranteed performance curve — losing 0.5% per year is expected, not a defect
- Installation by an unaccredited installer — installs not done by an MCS-certified contractor often invalidate the module warranty
- Combined re-roof + PV interface issues — careful documentation of who is liable for which interface element is essential to avoid disputes
How to make a solar warranty claim
- Generation monitoring data identifies underperforming modules. Without monitoring, you can't detect breach.
- On-site test by your O&M contractor confirms the fault.
- RMA raised with manufacturer by the installer or O&M contractor.
- Replacement modules supplied by manufacturer.
- On-site swap and recommissioning by installer.
Typical claim resolution: 4–8 weeks. If your original installer has ceased trading, your Insurance-Backed Warranty provider takes over the project management. See our detailed warranty claim support process and warranty claims overview.
Warranty specifications we provide as standard
- Tier-1 modules with 25-year product warranty + 25/30-year linear performance warranty
- Inverters with 10-year warranty as minimum (12–15 years available)
- 10-year workmanship warranty from us as installer
- IWA Insurance-Backed Warranty included as standard
- Ongoing remote monitoring as part of our standard O&M contract — any performance shortfall detected within days, not years
- Full RMA project management on every warranty claim — you don't deal with the manufacturer directly
What to ask any solar installer about warranty
- What product warranty does the module manufacturer provide, and is it tier-1?
- What performance warranty curve is guaranteed at year 25?
- What's the inverter warranty duration and is extension available?
- How long is the workmanship warranty?
- Who is the Insurance-Backed Warranty provider, and is it included in the quote?
- How does the warranty claim process actually work?
- Will I get ongoing monitoring data so I can prove a breach?
- What happens to my warranty if you (the installer) cease trading?
See also our UK farm solar installer checklist for the full 30-question evaluation framework.
Solar panel warranty — common questions
What is a typical solar panel warranty length in the UK?
UK MCS-certified solar PV systems carry three distinct warranties: (1) Product warranty 12–25 years covering module defects; (2) Performance warranty 25–30 years guaranteeing minimum power output over time (typically 80–87% of original output at 25 years); (3) Inverter warranty 5–12 years depending on manufacturer. Workmanship warranty from the installer is typically 2–10 years. An Insurance-Backed Warranty (IWA or similar) protects you if the installer ceases trading.
What is Insurance-Backed Warranty (IWA) and is it required?
An Insurance-Backed Warranty is a third-party insurance product that pays out if your installer goes out of business and can't honour their workmanship warranty. RECC (Renewable Energy Consumer Code) and TrustMark both require certified installers to provide an Insurance-Backed Warranty on every install. IWA is the most widely recognised provider in the UK solar sector. Without IBW, if your installer fails, your workmanship warranty becomes worthless. We provide IWA-backed cover on every commercial farm install as standard.
What is a solar panel performance warranty?
A performance warranty guarantees that the modules will continue to produce a minimum percentage of their rated output over time. Industry-standard performance warranties: ~98% output in year 1, then linear degradation to ~84–87% at year 25. Premium modules (LONGi Hi-MO, JA Solar DeepBlue, REC Alpha) typically guarantee 87–92% at year 25. If real-world generation falls below the guaranteed curve, the manufacturer must repair, replace, or refund. We provide ongoing generation monitoring as standard so any breach is detectable and actionable.
Does the warranty cover inverter failure?
Inverter warranties are typically 5 years standard with extensions to 10 or 12 years available at additional cost. Inverter failure is statistically more common than module failure — most premium brands (SolarEdge, SMA, Huawei, Fronius) now offer 10-year warranties as standard on commercial-grade products. We specify 10-year inverter warranty as a minimum on every farm install and recommend extending to 12 or 15 years where the install economics support it.
Are there warranty differences between residential and commercial solar?
Commercial and agricultural solar installs typically carry the same module-level warranties as residential (product 12–25 yrs, performance 25–30 yrs) but the workmanship and IBW arrangements are different. Commercial workmanship warranties typically 5–10 years depending on installer; IBW cover is required by RECC for both segments. Performance monitoring requirements are stricter on commercial installs — we provide remote monitoring as standard so any performance shortfall is detected within days, not years.
What's typically NOT covered by a solar panel warranty?
Standard exclusions include: lightning strike (covered by buildings insurance, not module warranty); flood / storm damage (also buildings insurance); accidental damage during cleaning or maintenance; cosmetic defects that don't affect performance; degradation within the guaranteed performance curve (i.e., losing 1% per year is expected, not a defect); and damage from incorrect installation by an unaccredited installer. Combined re-roof + PV projects specifically need careful documentation of who is liable for which interface element to avoid warranty disputes.
How do I make a solar panel warranty claim?
Start with your installer — they typically project-manage the claim with the manufacturer. The standard process: (1) generation monitoring data identifies the underperforming module(s); (2) on-site test confirms fault; (3) installer raises RMA with manufacturer; (4) replacement module(s) supplied; (5) installer swaps faulty for new. Most claims resolve in 4–8 weeks. If your original installer has ceased trading, your Insurance-Backed Warranty provider takes over the project management. We provide ongoing warranty support as part of our standard O&M contract — see /farm-solar-warranty-claim-support/.