Repair vs replace your solar inverter — Scotland 2026
Quick answer
Repair usually makes sense when an inverter is still under warranty and has a communication or grid-trip fault. Replacement is usually better when the unit is ten years or older, out of warranty, or showing a hardware fault such as an insulation, arc or IGBT error. A survey confirms the right option for your system.
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Verdict: If your inverter is under 8 years old and the fault is a communication error, grid trip or firmware issue, repair is usually the better option. If it is 10+ years old, or the fault is a hardware failure (IGBT, relay, DC bus), replacement almost always makes more sense — a new inverter with a 10-year warranty costs less over its lifetime than repeated repairs on ageing hardware. Choosing a hybrid inverter at replacement time adds roughly £500–£1,000 but avoids a second installation (and second DNO notification) when you later add a battery, saving £800–£1,500 in future labour.
Assessment by Scottish Energy Efficiency, August 2026. Costs are indicative ranges based on Scottish supply-and-fit quotes. Your actual costs depend on system size, access, and inverter brand.
| Factor | Repair | Replace | Our assessment |
|---|---|---|---|
| Upfront cost | £150–£500 | £1,000–£1,800 (string) £1,400–£3,500 (hybrid) | Repair cheaper short-term |
| Typical lifespan after work | 1–3 years (if inverter already 10+ years old) | 10–15 years (new inverter) | Replace wins long-term |
| Risk of repeat failure | Moderate–high on ageing hardware | Low (new warranty) | Replace wins |
| Battery-ready? | No (string inverter stays) | Yes (if hybrid chosen) | Replace wins if battery planned |
| Second DNO notification needed later? | Yes, if you later add battery | No (hybrid handles it) | Replace avoids a second notification |
| Warranty | Labour warranty only (parts case-by-case) | 10-year manufacturer warranty | Replace wins |
| VAT | Ask us about eligibility | Ask us about eligibility | Confirmed on your quote |
| Downtime | 1–2 hours | 1–2 hours (same-day for most systems) | Equal |
| SEG eligibility | Maintained | Maintained (we file G98/G99) | Equal |
When repair makes sense: Communication faults, grid over/under-voltage trips, and firmware bugs on inverters under 8 years old. These are often resolved with a board swap or firmware update at a fraction of the cost of a full replacement.
When replacement is the right call: Arc faults, insulation faults, IGBT failures, relay failures, or any hardware fault on an inverter over 10 years old. The cost of a new inverter with a full warranty is almost always better value than repairing equipment that has reached end of design life.
The hybrid question: If you think you might add a battery in the next 5 years, a hybrid inverter at replacement time costs £500–£1,000 more than a standard string inverter — but saves you the cost of a second installation (typically £800–£1,500 in labour, scaffolding, and a second DNO notification). It is almost always worth doing once the inverter has failed anyway.
Sources: indicative pricing based on Scottish supply-and-fit quotes, August 2026. Warranty terms from manufacturer specifications. VAT relief per HMRC VAT Notice 708/6. All figures are ranges; a site survey gives exact figures for your system.