What should I look for in a warranty when purchasing a solar thermal system?

When choosing a warranty for a solar thermal system in the UK, focus on coverage duration, component-specific protection, and installer guarantees. Pay attention to three key warranty types: product warranties for manufacturing defects, performance warranties for energy output, and workmanship warranties for installation quality.

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1. Warranty types and durations

• Product warranty: Covers defects in materials (e.g., collector corrosion, pump failures). UK suppliers typically offer 10+ years on collectors, with some extending to 15 years.
• Performance warranty: Ensures energy output levels (rare for thermal systems compared to PV panels, but verify if included).
• Workmanship warranty: Protects against installation errors. Seek 10-year coverage from MCS-certified installers, now common through schemes like Solar Together.

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2. Critical components to verify

• Collectors: Minimum 10-year coverage for vacuum tubes/panels.
• Hot water cylinder: 5–10 years for integrated systems.
• Pumps/controllers: 2–5 years typically – consider extended warranties.
• Mounting hardware: Included in 10-year product warranties from reputable suppliers.

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3. Recent UK-specific considerations

• MCS certification: Required for eligibility in government incentive schemes and often includes enhanced warranty terms.
• Insurance-backed guarantees: Becoming common among installers to protect against company insolvency.
• Hybrid system warranties: If combining solar thermal with PV, ensure compatibility between warranties.

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4. Common mistakes to avoid

• Assuming all components are covered equally: Cylinder warranties often lag behind collector terms.
• Overlooking excess clauses: Some warranties require paying the first £100–£250 of any repair.
• Ignoring maintenance requirements: Most warranties require annual servicing by accredited technicians.
• Choosing based on price alone: Cheap systems often have 5-year collector warranties vs 10+ years for premium brands.

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5. Practical tips for UK buyers

• Request insurance-backed guarantees: Provides protection if the installer goes bankrupt.
• Verify transferability: Essential if selling your property (most 10-year warranties can transfer to new owners).
• Check claim response times: Leading suppliers offer 7–14 day repair commitments.
• Compare inverter warranties (if hybrid system): 5–10 years is standard – consider models with replaceable parts.

For small businesses, ensure warranties account for higher usage patterns – some domestic warranties void coverage if used commercially. Recent installations under government-backed schemes (e.g., Public Sector Decarbonisation Scheme) often include enhanced warranty requirements you can benchmark against.