Solar inverter replacement in NZ: lifespan, faults and what to replace it with

How long does a solar inverter last?

About 10 to 15 years, depending on quality and how hard it works, according to EECA. That's roughly half the life of the panels, so most systems need one inverter replacement over their lifetime. Many systems installed in New Zealand's first wave of home solar are reaching that age now.

Heat shortens an inverter's life. One mounted in full afternoon sun or in a hot, unventilated garage ceiling space works harder than one on a shaded, airy wall, which is worth raising if yours is being replaced.

How do I know if my solar inverter has failed?

Check on a sunny day around midday. If the monitoring app or the inverter display shows little or no generation, a red light or an error code, or the display is blank, the inverter has either stopped or lost its connection to the panels or the grid. Write down the error code before resetting anything.

• The display is blank, or shows a red or orange fault light
• Generation in the app has dropped to zero, or far below the same month last year
• Your power bill has risen and export credits have stopped
• The inverter is tripping its breaker, buzzing loudly or smells hot

What should I check before calling anyone?

Only the things you can do without opening anything. Check the solar breaker in the switchboard and the AC isolator next to the inverter are on, and look for a tripped breaker. If the app is offline but the inverter display looks normal, the problem may just be Wi-Fi. Don't touch the DC isolators or wiring on the roof side: they stay live whenever the sun is up.

Is a failed inverter covered by warranty?

Often, if it's inside the maker's warranty period, which is commonly 5 to 10 years and longer for some brands. Some makers only honour the full term if the inverter was registered after installation. Have the install date, the inverter's model and serial number, and the original invoice ready when you call.

What should I replace an old inverter with?

A like-for-like string inverter matched to your panels is the simplest replacement. If you think you might want a battery in the next few years, ask for a hybrid inverter instead: it manages both panels and a battery, so adding storage later doesn't mean replacing the inverter again. Either way, the replacement has to meet AS/NZS 4777.2 and your lines company may need to be told.