The honest answer most solar salespeople won’t lead with is that solar is a genuinely excellent investment for some New Zealand homes and a fairly average one for others — and the difference usually has little to do with the thing everyone fixates on, which is the roof. Before you commit $12,000–$16,000, it’s worth knowing which group your household actually falls into. The good part: once you understand the one factor that drives it, you can usually tell in about five minutes.
The one thing that decides it: when you use power
Here’s the idea that makes everything else fall into place. A solar panel only saves you real money when you use the electricity it makes, at the moment it makes it. That’s called self-consumption, and it sits at the heart of the whole decision.
Why does it matter so much? Because the power you use straight from your own panels is worth the full retail price you’d otherwise pay — around 39 cents per kilowatt-hour in New Zealand. But the surplus you don’t use gets exported to the grid, and your retailer pays you far less for it — often somewhere between about 7 and 17 cents, depending on who you’re with. So the very same unit of solar electricity can be worth roughly three to five times more if you use it yourself than if you sell it back.
That single fact is what sorts New Zealand homes into the ones solar suits and the ones it doesn’t — at least not yet.
The homes solar suits best
If your household uses a decent amount of electricity during daylight hours, solar is very likely a strong buy. You’re the home that turns midday sunshine straight into savings at the full retail rate, day after day. In practice that means:
- Someone’s home during the day. A family with young kids, shift workers, retirees, or anyone now working from home. The dishwasher, the washing machine, and the heat pump all running while the sun is up is exactly the pattern solar rewards.
- You’re a higher-than-average power user. Bigger homes, electric hot water, a pool pump, or a couple of heat pumps ticking over through the day. The more daytime load you have, the more of your own cheap solar you soak up instead of exporting it.
- You own (or want) an EV you can charge in daylight. An electric car is a big, flexible daytime battery on wheels. Topping it up off your own panels is one of the best returns in the entire solar equation.
- You’re planning to add a battery. A battery stores the midday surplus for use after dark, which lifts self-consumption sharply — and widens the range of homes solar makes sense for.
If you recognise your household here, the roof details matter far less than you’d expect. The economics are already working in your favour.
The homes that should probably wait
Solar isn’t wrong for these homes forever, but the numbers are thinner today, so there’s no need to rush:
- The house sits empty all day. If everyone’s out from eight to five and the big appliances only run in the evening, most of your solar gets exported at the low rate while you buy expensive power back at night. You’ll still save something, but the payback stretches out — and it’s a battery, or a deliberate shift of usage into daylight, that fixes it.
- You’re already a very low power user. If your bills are small, there’s simply less to save, and a fixed up-front system takes longer to repay against a modest bill.
- You’re about to sell or do a major roof renovation. If you won’t be there long enough to bank the savings, or the roof is coming off in two years, wait until the dust settles — taking panels down and refitting them is wasted money.
- You’re renting. You usually can’t bolt panels to a house you don’t own. The landlord-and-tenant version of this has its own awkward economics, covered separately.
None of these are permanent disqualifications. Shift your usage into daylight, add storage, or wait for the export-pricing reforms below, and several of these homes move into the “worth it” column.
Where the roof comes in — and where it doesn’t
The roof does matter; it’s just a tie-breaker, not the headline. What helps:
- Direction. North-facing is ideal in New Zealand. East and west still work well, with the peak simply shifted earlier or later in the day. South-facing slopes are the weak spot.
- Shade and pitch. A roof free of heavy shade from trees, chimneys, or a neighbour’s two-storey wall will comfortably out-earn a shaded one. Shade is the real performance-killer here, and it’s worth taking seriously.
- Space and condition. You need room for a sensible 5–6.6 kW array — a dozen or more panels — on a roof that won’t need replacing soon.
Notice the order, though. A perfect roof on an empty daytime house is still a slow payback, while an average roof on a high-daytime-use home is a good one. Usage first, roof second.
The 2026 change worth knowing about
There’s a reason the “wait” group may shrink soon. From 1 July 2026, the Electricity Authority is requiring larger retailers to offer time-of-use pricing and fairer rates for the power you export at peak times. That tilts the maths a little more towards exporting households — the very homes that look marginal today. If you’re on the fence, it’s a reason to keep watching, not a reason to wait indefinitely.
So — which group are you in?
Strip it back to a single question: will you actually use the power while the sun is shining? If yes — you’re home during the day, you’re a heavy user, you’ve got an EV or a battery in mind — solar is very likely a sound investment, and the next step is a proper assessment. If your house sits empty all day and your bills are already small, solar still works, but it’s a battery conversation or a “revisit in a year” one, not an urgent buy.
The whole point is to decide on the thing that genuinely drives the return — your usage pattern — rather than on a salesperson’s roof survey. Want it worked out for your specific household? Our free assessment models your usage, your roof, and your likely payback together, so you know exactly which group you’re in.
Sources: Retail and export price ranges per MBIE and the Electricity Authority; EECA — solar for homes; 1 July 2026 reforms per the Electricity Authority. Figures are indicative and vary by home and retailer.