Solar Panel Warranty Guide: What to Look For

1. Product Warranty (Manufacturing Defects)

Covers: defects in materials, workmanship, and manufacturing. If a panel fails due to a factory defect, the manufacturer replaces it free of charge.

• Standard panels: 10–12 years
• Mid-range panels (JA Solar, Trina, Longi): 12–15 years
• Premium panels (SunPower, REC Alpha): 25 years

What it covers: cracked cells, delamination, junction box failure, frame defects, backsheet failure, hot spots caused by manufacturing defects.

What it does NOT cover: damage from storms, pests, poor installation, or normal wear.

2. Performance Warranty (Output Guarantee)

Guarantees that the panel will produce a minimum percentage of its rated output over time.

• Year 1: typically 97–98% of rated output
• Years 2–25: 0.4–0.55% degradation per year
• Year 25: typically 80–85% of rated output guaranteed

If a panel's measured output falls below the guaranteed level, the manufacturer replaces it or provides compensation.

Standard: 80% at 25 years Premium (SunPower): 92% at 25 years Premium (REC Alpha): 86% at 25 years

Source: Manufacturer warranty documentation.

The inverter has a separate warranty from the panels:

String inverters: - Standard warranty: 5–10 years - Extended warranty (paid): up to 15–20 years - Extension cost: £100–£300 - Brands: GivEnergy (5yr std), Fronius (5yr std, ext to 20), Solis (5yr std)

Micro-inverters: - Standard warranty: 20–25 years - No extension needed — already matches panel lifespan - Brands: Enphase IQ8 (25yr), AP Systems (25yr)

Hybrid inverters: - Standard warranty: 5–10 years - Extension available from most manufacturers - Brands: GivEnergy (5yr std), SolarEdge (12yr std, ext to 25)

Recommendation: If you choose a string inverter with a 5-year warranty, buy the extended warranty at installation. It is far cheaper to extend upfront than to pay for an out-of-warranty replacement later (£800–£1,500).

Source: Manufacturer warranty terms.

In addition to manufacturer warranties, your MCS-certified installer provides a workmanship warranty covering the installation itself:

• Typical period: 5–10 years (some premium installers offer 15–20)
• Covers: roof leaks from mounting brackets, wiring faults, incorrect installation, scaffolding damage
• Does NOT cover: panel or inverter defects (those are manufacturer claims)

Important: If your installer goes out of business, the workmanship warranty may be worthless. Mitigate this risk by: - Choosing established installers with 5+ years in business - Checking if the installer carries Insurance-Backed Guarantees (IBG) — these continue to apply even if the installer ceases trading - Keeping all installation documentation and certificates

Source: MCS consumer protection requirements.

Panel warranty comparison (2026):

| Brand | Product Warranty | Performance @ 25yr | Notes | |-------|-----------------|-------------------|-------| | SunPower Maxeon | 40 years | 92% | Best in industry | | REC Alpha | 25 years | 86% | Strong all-round | | Canadian Solar HiHero | 25 years | 84.8% | Excellent value | | Longi Hi-MO | 25 years | 84.8% | Largest manufacturer | | JA Solar DeepBlue | 25 years | 84.8% | Popular in UK | | Trina Vertex S | 25 years | 83.1% | Good value | | Jinko Tiger Neo | 25 years | 84.8% | Cost-competitive |

Key takeaway: Most mainstream panels now offer 25-year product warranties — a significant improvement from 5 years ago. The performance guarantees are converging around 84–86% at year 25. SunPower remains the outlier with 40 years and 92%, but at a significant price premium.

Source: Manufacturer published warranty terms, March 2026.