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Expert opinion from University of Auckland – Waipapa Taumata Rau
Solar potential maps of New Zealand show that we’ve got a lot of it. Potential, that is. When it comes to generating energy solar power, New Zealand is flatlining as other countries are skyrocketing.
That’s despite multiple reports and studies showing that solar energy could cut the average household’s annual power bills by at least $1000 and provide the country with more energy security.
Farmers who install solar could halve their energy costs while also making some income selling electricity back into the grid, says the Energy Efficiency and Conservation Authority.
Next year, solar is predicted to overtake coal as the world’s biggest electricity-generation source.
But in New Zealand, the up-front expense of installation remains a hurdle – the average household solar system costs $16,500. While numerous national or state governments overseas offer subsidies, rebates, feed-in tariffs, tax credits, or other incentives for households to install solar, New Zealand stands out for its lack of support.
However, there’s also perhaps a psychological obstacle at play, suggests Ralph Cooney, a professor emeritus, chemical sciences, at the University of Auckland.
When considering whether to invest in rooftop solar, people usually focus on how long the payback period will be, says Cooney: how many years it’ll take for the savings on power bills to compensate for the cost of installation.
That skips an important aspect of switching to solar energy, says Cooney.“New Zealanders tend to view rooftop solar as, ‘It has to pay for itself’,” he says. “Without looking at the fact that you’ve actually improved the capital value of the property.”
Instead, says Cooney, the addition of solar should be regarded the same as adding other amenities to a property, like a deck. No one expects a deck to pay for itself. “But you would say, ‘I’ve improved the property, so when I sell the property, I’ll get the value of the deck.’ Now, people don’t think of solar in those same terms, but they should do. It’s a capital improvement on the property that actually is attractive to a new buyer.”
Earlier this month, the financial journalist Frances Cook calculated that her household’s switch to solar energy has been an investment with a higher rate of return than the stock market – without accounting for future power-bill savings after the payback period.
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The biggest savings involve combining rooftop solar with electric vehicle use, says Cooney: “It enables EV owners to drive their car free of fuel costs.”
Across the ditch, Australia is a world leader in solar energy, with around a third of all households in the country having some form of solar generation. While Australia has a great deal more sunlight hours than New Zealand, that isn’t entirely the reason it made the switch so quickly to solar, says Cooney.
“The government there has provided incentives for residential solar in a way that the New Zealand government never did.”
Not all Australia’s financial incentives remain, but the country still has a rebate for solar installation. But here, solar subsidies are limited to a handful of community projects and schools. Until last October, adding rooftop solar to a New Zealand residential house required building consent.
Permitting requirements remain an obstacle to on-farm solar projects, says Federated Farmers. A survey by the organisation found that 70 percent of respondents were interested in installing solar on their farm.
Last July, Federated Farmers called for streamlining regulations, the rules and costs of which vary wildly depending on the region. In most areas, farmers must obtain resource consent – and in Canterbury, farmers also must obtain a stormwater consent for rain dripping off the panels.
“Solar and wind and some other forms of renewables can be set up so that they don’t require the same extensive massive grids that we’ve had in the past,” says Cooney.
That’s something the Pacific islands are beginning to capitalise on, with a focus on solar over other renewables. “They’re very highly motivated to move into renewables, and they are reluctant to move into wind because of the risk of cyclones destroying the infrastructure.”
Samoa was the first country in the Pacific to install battery energy storage systems, in conjunction with a large solar farm across the road from the airport. It now saves the airport hundreds of thousands of dollars per year in energy costs.
Here, an increase in solar generation could help retain more water in the country’s hydro lakes in dry years: Cooney wants to see an increase in utility solar, which is distributed via the grid. Currently eight solar farms are operational in New Zealand, with another nine under construction.
On a household level, stored solar energy can provide security during weather events when mains power is cut as during Cyclone Gabrielle, when more than 200,000 households lost power for up to a week.
That security increases when households also own an EV – their substantial battery capacity can be used to power a home if mains power is cut or solar generation lags. “It is an interesting little bit of insurance, if you like, for a household,” says Cooney.
“We just don’t get the solar energy that some other places get,” says Cooney. “The places around the world that scream out saying, ‘This is a great place for solar’, are places like Western Australia and North Africa. Those countries are really going ahead with it.”
That shouldn’t hold us back, says Cooney. For a long time, the world leader in solar power was Germany, which is hardly known for its sunshine hours. Instead, the government provided financial incentives, and the public took them up. Now, around a fifth of Germany’s electricity comes from solar, and its success paved the way for Australia’s strategy and energy transition.
The Solar Potential Map for Auckland, created by three University of Auckland researchers, uses LIDAR data to indicate how much electricity could be generated on city rooftops. The answer is: plenty. Non-leafy suburbs have the solar advantage – as those trees provide shade – with areas in the southeast of the city receiving the highest ratings for solar generation.
Paradoxically, solar uptake in New Zealand doesn’t always coincide with the sunniest spots. While the country’s sunniest town in 2025 was New Plymouth (again), Taranaki lags at 17th out of 39 regions for solar uptake.
“Solar’s the cheapest energy we’ve got,” says Cooney. “It’s provided for free by nature. So why wouldn’t we actually embrace it?”
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Science journalist Rebekah White works as a sustainability communications adviser at the University of Auckland. She is former editor of New Zealand Geographic magazine. More by Rebekah White
13 Comments
I totally agree. The returns from solar should be compared with the returns on any other investment. “Payback time” is not relevant, as it measures the time to achieve a 100% return, often unachievable in the short or medium term with any investment.
The backers of the Modern Slavery Bill say that 97% of polysilicon for solar panels is made by slave labour, NZ is ahead of the curve in refusing to support these practices by not buying solar.
The biggest reason for backing solar is driven by artificially high hydro electricity prices driven by our monopoly gentailers. Like Tasmania , which has a cable supplying Melbourne, NZ has abundant water storage . The solar panel industry depends on imported battery technology and materials
Actually, NZ has very limited water storage, we have a small number of mainly snow/glacier melt fed lakes which relatively quickly run out of water in colder and dryer years
NZ is so far behind on solar, in part for the reasons stated: stupid regulations, and excessive installation costs. But also the strong resistance from the electric companies and the Gentailers.
NZ has barely 10% of the solar that South Australia, NSW and Victoria have. Germany has 40GW rooftop = 480 MW per million people. (33% larger area than NZ).
NZ has 200 MW rooftop or <40 MW per million (12x less); or 160x less per area.
So-called "balcony" solar is very popular: zero installations costs and it can be mounted on a balcony for those without a roof, such as renters.
You just plug it in!
The aversion to intermittency, especially by the electric companies who can't manage it, is a major issue in NZ that could be solved by an integrated system that uses hydro as a storage device instead of costly batteries. But that requires cooperation and likely changes imposed by the government. The ability to feed excess power into the grid and get it back later should be mandated by the government (called net metering). The companies get power with zero investment. But this would likely eliminate the small electric compamies.
NZ is so far behind just about everywhere and it is holding our economy back!
There has been a long history of the generation of confusion and doubt about PV Solar even though it has been the lowest cost form of energy production for many years. With grid and home battery prices now also competitive with GT spinning reserves the distributed Solar/Battery concept is a winner. However, the Govt is conflicted by its 51% ownership of Gentailer assets where it collects about $1.5b/annually in GST and dividends that goes into general taxation. Because Rooftop solar is behind the meter there seems to be an effort to discourage its growth with even more confusion and doubt. Oddly neither of the main parties seem to be as concerned as NZF in the resulting closures of sawmills and Frozen foods. Let’s hope the truth will be revealed under the current oil crises!
Thank you for answering the question posed by the headline, Dr. Trenberth. NZ’s aversion to regulating major industries (even natural monopolies) and the power of lobbying, result in failure to adopt and implement real policy changes.
These two statements warrant further investigation:
“… a psychological obstacle at play.” My grandson in Australia bought a house with solar panels and runs an economical hybrid car. By comparison, I find there’s a strong conservative backlash against solar and electric or hybrid cars here in NZ, particularly amongst Gen X.
Grant says: “97% of polysilicon for solar panels is made by slave labour …” Rather than simply making that a reason not to go with solar, a global investigation needs to be conducted and manufacturers forced to abide by international law. (A big ask these days when the US is blatantly flaunting international laws, but that’s not a reason to abandon hope and let the international criminals run free.)
We need to understand how general the reluctance is – it’s who we are, looking at the larger historical / cultural context. This is a Post Truth Era where denial has reached mainstream.
Legislation that guaranteed that any surplus energy sold back to the grid, must be at a rate close to what consumers paid for energy bought from the grid, would boost the installation of solar panels over night.
In know it’s a pipe dream, but if ChatGPT is right (who knows) we need 44 TWh, and already have 37 TWh non-combustion generation. ‘It’ estimates 14 TWh from fully exploited solar (from every feasible home, business and factory rooftop) and related batteries, with the surplus 6 TWh filling Lake Onslow, which would supply the 4 TWh in winter and dry years to complete the requirement. Yes, a pipe dream, but … wouldn’t it be nice? Disclosure: Rooftop with 19 kWh, battery and two Leaf cars.
The 97% number is commonly misquoted. It does not mean that 97% of polysilicon is made by slave labour. What reputable sources actually say is: ~97% of global solar wafer manufacturing occurs in China, not that 97% of polysilicon is produced with forced labour. Some advocacy groups state that up to 97% of polysilicon‑based solar panels are at risk of exposure to forced labour somewhere in their supply chains — “at risk” ≠ “proven forced labour”
About 35–50% of the world’s solar‑grade polysilicon has been produced in Xinjiang (Uyghur Region) in recent years, where state‑imposed forced labour programs are well documented.
It is safe to say, “A significant share (roughly one‑third to one‑half) of the world’s solar‑grade polysilicon has been produced in Xinjiang, China, where credible evidence shows the use of state‑imposed forced labour, and global solar supply chains remain highly exposed to this risk.”
Encouraging solar power and EV cars and using the hydro lakes as a temporary battery while planning ahead for the big one, Lake Onslow, is such an elegant answer to our long term energy needs, that I cannot understand why the present government can’t see it. So is reinvesting in rail and having adequate Cook Strait ferry services. But then I was a pre-WW2 baby, brought up with old school values, cash payments and jam jar accounting, which I still practise today. I have solar power and an EV car and use Meridian as the battery. The difference between their charging and buyback prices is ridiculously low but it’s convenient and hopefully will reduce. Even so, every week, just $20 goes to Meridian to cover the cost of the additional electricity I need in my all electric house in the winter. No one can tell me that solar and EVs aren’t economical.
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