Mar 18, 2025
Newstalk ZB
If electricity supply is the problem, solar is part of the answer in the long-term

On Newstalk ZB, Energy Resources Aotearoa chief executive John Carnegie spoke with Mike Hosking about the need for coal and gas to provide enough electricity in what looks like another dry year. But there is another option.

GAs and coal will be required in the short term, but we would argue that "it's the answer" mostly because the extra renewable generation hasn't been built fast enough; it's a bit like saying McDonald's is the answer for dinner after forgetting to go to the shops.

Rewiring Aotearoa has a different (and cheaper) answer to the supply problem.

Our hydro system is basically a massive battery and more rooftop and ground mount solar on our homes, farms and businesses could keep water in the hydro lakes for when we need it most.



It's a particularly compelling option in a dry year where there is an average 11% increase in solar production. When it's not raining, it's shining and, as the graphic shows, that 11% bump creates a significant amount of additional hydro storage - and it could be rolled out a lot more quickly than a new gas field.

A briefing to the new Energy Minister talks about households and businesses finding energy unaffordable. We always come at these issues from a customer perspective and generating your own electricity for your own electric machines is not only good for the energy system, it's the cheapest option for customers.

Like highways, peak times are the main concern, but the grid can handle it if we adopt new technology and change our behaviour.

For example, Forest Lodge Orchard produces around 80% of the electricity it needs to run its 21 electric machines via rooftop and ground mount solar. It stores a lot of that electricity in batteries, so while its electricity consumption has increased dramatically, it doesn’t use any more electricity at peak times.

It can actually be a net positive by exporting during congestion times and powering roughly 25 neighbouring homes.

At a household level, home batteries (and soon enough batteries that come with free wheels AKA electric vehicles with bidirectional charging that can power your house or feed back to the grid) make those calculations even better.

Heating water, which makes up around 30% of a home’s energy use (if you don’t count your car), can also be timed for the solar window.

The long-term answer to our electricity issues is not sitting at the bottom of the ocean or on a ship sent from Indonesia. At least part of the answer is beaming down from the sky.

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