People installing solar power systems with batteries on their homes, hoping to avoid the disruption of a power cut, are being told to check with the installer that the battery can provide that protection.
About 10 percent of those installed in recent years may not have the capacity to deliver it, industry experts say.
Kristy Hoare, managing director of My Solar Quotes, told RNZ this week that about half of people getting a quote for solar were including a battery. She said, although that could double the cost of the system, many people wanted them for energy independence or as a backup during outages.
But a spokesperson for Rewiring New Zealand said having a battery system that would flick on in a power cut was something that needed to be built into the installation process, and people would have to request it.
They needed to be able to disconnect from the grid in the event of an outage.
"Battery systems do this automatically in a lot of homes and buildings, but you need to ask for it specifically. The part is called an automatic transfer switch. It detects the grid going down and cuts you off from it. You have to be cut off because feeding energy back onto a dead grid is dangerous for the people working on it."
Gareth Williams, chief operating officer at Sustainable Energy Association of New Zealand, said it would be disappointing if people did not realise their system was not set up to cover a power cut because it was something that installers should discuss with customers. He said sometimes an extra piece of hardware was needed, and in all cases there would be additional costs to connect to the system.
Powerswitch general manager Paul Fuge.
Supplied / Consumer NZ
Powerswitch general manager Paul Fuge agreed.
"Any reputable installer should be discussing this with customers during the purchase and installation process, so it shouldn't come as a surprise after the system has been commissioned.
"It's also worth noting that batteries remain relatively expensive and can almost double the cost of some solar installations. For some households, the economics of adding a battery may not yet stack up. Regardless they may be willing to pay the additional cost because of the resilience and backup power a battery can provide, particularly in areas that experience frequent outages or where people are concerned about the impacts of natural disasters.
"As extreme weather events become more common and power outages potentially increase, we would expect to see more households installing battery systems for resilience as well as for any economic benefits they may provide."
Hoare said all solar battery models on the New Zealand market could now provide power during an outage.
Kristy Hoare, managing director of My Solar Quotes.
Supplied / My Solar Quotes
"A few years ago, some solar battery options completely lacked this function, but those models are no longer available."
She said some batteries required additional components and the system had to be specifically installed.
"Given how useful backup power is during an outage, and that the additional hardware is generally only part of the overall system cost, it would make little sense to install one of these batteries without enabling backup."
She said she would estimate about 90 percent of systems had backup power available.
"Going forward from this year, closer to 100 percent of batteries will have backup."
Sign up for Money with Susan Edmunds, a weekly newsletter covering all the things that affect how we make, spend and invest money.
© Copyright Radio New Zealand 2026
You have JavaScript disabled. Without it you will not be able to play audio or video, please enable JavaScript in your browser.

source