Commercial Solar PV Warranties: What's Actually Covered

The warranty stack

A commercial solar PV system has five separate warranties from four different parties. Understanding what each covers is critical at procurement stage because warranty mismatches are the most common source of disputes 5-15 years post-install.

1. Panel warranties

2. Inverter warranties

Most inverters need at least one replacement during the 25-year panel life. KMM commercial customers typically budget £4,400-£5,700 for one replacement at year 10-12 (a 50kW inverter swap).

3. Battery warranties (where fitted)

• Capacity warranty — 80% capacity retention typically guaranteed for 10 years and 6,000 cycles, whichever comes first
• Component warranty — 10 years on the battery cells and BMS
• Cycle count — full daily cycling for 10 years equals ~3,650 cycles, well within the 6,000 limit

4. Mounting and balance-of-system

• K2 / Renusol / Schletter mounting — typically 10-12 years against corrosion and mechanical failure
• MC4 connectors — 25 years if installed correctly with manufacturer tooling
• Cabling and isolators — 25 years if appropriately rated and installed

5. KMM workmanship warranty

• Installation workmanship — 5 years from commissioning, covering any installation-related defect
• Insurance-backed warranty — for domestic installs via HIES or IWA (commercial installs handled bilaterally)
• Performance guarantee — KMM commits in writing that year-1 generation will be within 10% of the modelled output, assuming normal weather (cumulative shortfall measured against 10-year UK average climate data)

What's NOT covered (common gaps)

• Theft — covered by your buildings insurance, not solar warranty
• Storm damage — covered by your buildings insurance
• Lightning strike — usually covered by buildings insurance, plus surge protection if specified
• Bird damage — not covered (fit bird-proofing at install if relevant)
• Misuse or accidental damage — not covered
• Generation shortfall due to shading you added after install (new building next door, trees growing)
• Cosmetic damage — not covered (panels can have minor cosmetic blemishes that don't affect output)

How to claim

1. Contact KMM first — for the first 5 years (workmanship) we cover the cost regardless of cause
2. KMM assesses the issue and either fixes it under our own warranty or escalates to the relevant manufacturer
3. Manufacturer warranty claims are handled by KMM on your behalf — you do not contact the manufacturer directly
4. Replacement parts shipped to KMM and we fit them; you bear no labour cost during the manufacturer warranty period

Warranty transfer at property sale

All warranties transfer with the property at sale. KMM provides a documentation pack containing all warranty certificates that the property buyer's solicitor expects to see at completion.

FAQs