Your solar inverter is failing: 5 signs and what to do next

How long do inverters last?

Solar inverters typically last 10–15 years. If your system was installed during the Feed-in Tariff boom (2010–2015), your inverter is now 11–16 years old and may be approaching or past its expected lifespan. The panels themselves last 25–30 years, so the inverter almost always fails first.

The 5 signs

1. Error codes on the display

Most inverters have a small screen or LED indicators. Common fault codes include isolation faults (the inverter has detected a wiring issue), grid voltage faults (the inverter cannot synchronise with the grid), and overtemperature warnings. If you see a red light or an error code that does not clear after a restart, the inverter needs attention.

2. Complete shutdown

The inverter screen is blank, no lights, no humming. This can be a blown fuse (cheap fix) or a failed component (replacement needed). Check your consumer unit first — if the MCB for the solar circuit has tripped, reset it. If it trips again immediately, call us.

3. Generation has dropped significantly

Compare your current generation to your FiT statements from the first year. A drop of more than 15% over 10 years (beyond the expected 5% panel degradation) suggests the inverter is not converting efficiently. Modern inverters are 97–98% efficient; older models may have dropped to 90–93%.

4. Overheating or unusual noises

Inverters generate heat during normal operation, but if the casing is too hot to touch or you can hear buzzing, clicking, or humming that was not there before, internal components may be failing. Ensure the inverter has adequate ventilation — but if the noise persists, it needs replacing.

5. The monitoring app has stopped updating

If your inverter has WiFi monitoring and the app shows no data for days, the communication module or the inverter itself may have failed. Try restarting the inverter first. If the app still shows nothing, the inverter needs inspection.

What to do

If you recognise any of these signs:

1. Do not ignore it. A failed inverter means your panels are generating power that is not being used or exported. You are losing money every day.
2. Check your consumer unit. If the solar MCB has tripped, reset it once. If it trips again, call an installer.
3. Consider adding a battery at the same time. If you are paying for an engineer visit and a new inverter anyway, adding a battery at the same time saves on labour and gives you a complete modern system. A hybrid inverter (battery-compatible) costs roughly the same as a standard replacement.

What replacement costs

• Inverter only: £1,200–£2,500 installed
• Inverter + Duracell Dura5 battery: £5,000–£7,000 installed
• 0% VAT saving: £240–£1,400 (until 31 March 2027)

All prices are illustrative ranges. A free site survey gives your exact figure.

Will it affect my FiT?

No. Replacing your inverter does not affect your Feed-in Tariff payments. Adding a battery does not affect them either. These are protected upgrades. Only replacing panels or increasing capacity may affect your FiT contract — and even then, only if you do not notify your FiT provider in advance.

Source: Ofgem FiT guidance, checked August 2026. Always confirm with your FiT provider before making changes to panels.