Heat Pump or Solar First? Where to Spend $10k

Bottom line up front: For most Kiwi homes with old resistance heaters, wood burners, or a single noisy heat pump trying to do the whole house, a high-efficiency heat pump (or two) is almost always the better first dollar spent. It typically cuts your winter power bill faster and harder than solar can, because heating is where most of your energy actually goes. Once your heating is efficient and your bill profile is clearer, then solar PV does its best work, especially if you can pair it with a hot water cylinder timer or a battery. If you've only got $10k and you have to choose, do the heat pump first in most cases. If you can do both within 12 to 18 months, even better, and the order still favours heating first for cashflow reasons we'll walk through below.

This article is for the homeowner staring at a $10,000 ceiling, a cold lounge, and a power bill that makes them wince every July. We'll work through when heating wins, when solar wins, and how the two stack together so the second purchase doesn't undo the value of the first. No sales spin, just the numbers and the reasoning.

What "Heat Pump vs Solar First" Actually Means for NZ Homeowners

Here's the thing most quotes won't tell you plainly: solar reduces the cost of the electricity you use, but a heat pump reduces how much electricity you need in the first place. Those are two very different levers, and one is much sharper than the other for a typical Kiwi home.

According to EECA's Energy in New Zealand data and BRANZ household energy studies, space heating and hot water together account for around 60 to 70% of residential energy use in this country. We live in damp, poorly insulated homes by OECD standards, and we heat them inefficiently. A modern heat pump delivers roughly 3 to 4 kWh of heat for every 1 kWh of electricity drawn (that's the COP, or Coefficient of Performance). A plug-in resistance heater or an old element delivers 1:1.

So before you put a single panel on the roof, ask yourself: am I generating clean power to feed an inefficient appliance? Because that's a leaky bucket, and solar won't patch it.

The "$10k decision" framing

Ten thousand dollars is roughly the sweet spot where Kiwi homeowners feel the pinch of having to choose. It's enough for:

• A quality 5 kW solar system (panels + string inverter, no battery), professionally installed
• OR two to three high-spec ducted or high-wall heat pumps covering the main living and sleeping zones
• OR a smaller solar array plus one heat pump, with trade-offs on both sides

It's not enough for both done properly, which is why the order matters.

The Key Numbers: Where Your Energy Actually Goes

Let's ground this in a real Kiwi household. EECA's published guidance suggests the average NZ home uses around 7,000 to 9,000 kWh of electricity per year, with significant regional variation. Wellington and the South Island skew higher because of heating load. Auckland and Northland skew lower.

Of that annual usage, the breakdown typically looks like:

• Space heating: 30 to 35%
• Hot water: 25 to 30%
• Appliances and lighting: 25 to 30%
• Cooking and standby loads: 10 to 15%

If you swap an old resistance heater pulling 2 kW continuously for a modern inverter heat pump delivering the same warmth at 500 to 600 W, you cut that heating slice by 60 to 75% overnight. No roof work, no inverter, no export negotiations with your retailer.

What solar actually saves you (in dollars)

A well-sited 5 kW system in, say, Hamilton or Tauranga, will produce around 6,500 to 7,500 kWh per year. But here's the catch the door-knockers don't emphasise: you only save the full retail rate on the portion you self-consume in real time. Anything exported to the grid earns the buy-back rate, which is materially lower (see our current cost per watt and ROI breakdown for the live maths).

Typical self-consumption for a daytime-empty Kiwi home without a battery sits around 25 to 35%. The rest gets exported. So if your home is mostly empty during the sunshine hours, your $10k of solar is doing about a third of its theoretical job financially.

A heat pump, by contrast, saves you regardless of the time of day. Its value isn't gated by whether the sun's out.

When Heat Pump Wins First (the Common Case)

You should almost certainly do the heat pump first if any of these describe you:

• You currently heat with plug-in panel heaters, oil column heaters, or resistance fan heaters
• Your only heat source is a wood burner and you'd like to retire the chainsaw
• You have one tired old heat pump trying to heat a whole house through a single hallway
• Your winter bills are more than double your summer bills
• You're in a colder zone: Wellington, Wairarapa, Manawatū, Canterbury, Otago, Southland
• You have damp issues or condensation on windows (a heat pump's dehumidifying effect helps)

In these scenarios, a heat pump returns more comfort and more dollar savings per $1 spent, and it does so in year one. You feel the difference in July, not just on a spreadsheet.

Real-world example: the Manawatū villa

Take a 1920s villa in Palmerston North heated by two panel heaters and a tired old log burner. Annual electricity use sits around 11,000 kWh, with bills spiking to $450 in July. The owners are weighing a 5 kW solar array (~$10k) versus two ducted-zone heat pumps (~$9k).

The heat pumps cut their heating energy roughly in half (from ~4,500 kWh to ~2,000 kWh of heating draw, and far more comfortably). That's around $700 to $900 a year saved at typical Manawatū retail rates, with a payback of 10 to 12 years just on the heating alone, plus a warmer, drier house in year one.

The same $10k of solar, on the same house with the same daytime occupancy pattern, would save roughly $1,000 to $1,400 a year, but the comfort doesn't improve at all, and the winter bill barely moves because solar production in Manawatū in June and July is genuinely low.

The heat pump wins on winter cashflow and comfort. Solar wins on annual dollar offset but does little for the cold months.

When Solar Wins First (the Less Common Case)

Solar is the better first dollar in a narrower set of situations:

• Your home is already well-heated by modern heat pumps and well-insulated
• You have large daytime loads: someone home with the kids, a home office, EV charging midday, a pool pump
• You live in a sunny zone with high self-consumption potential: Northland, Bay of Plenty, Hawke's Bay, Nelson-Tasman, Marlborough
• You have an electric hot water cylinder you can timer-shift to soak up midday production
• You're getting an EV in the next 12 months and plan to charge during the day
• You're locked into a flat-rate retail plan with a poor winter outlook and want to hedge

If you're a tech-savvy optimiser with a dynamic tariff plan and an EV, solar starts to look genuinely strong. The arbitrage opportunity, especially with the dynamic buy-back rates we track in our costs and ROI pillar, can be excellent.

What This Means for You (By Persona)

The ROI Pragmatist

You want payback. The heat pump's payback is faster in most NZ homes because the saving applies to the most expensive kWh you buy (winter peak) and the most wasteful appliance you own (resistance heating). Do the heat pump first, watch your bill profile for 12 months, then size your solar to match the residual load. You'll avoid over-sizing your array, which is a common and expensive mistake.

The Tech-Savvy Optimiser

You see this as a system, not two purchases. You're right. But the sequencing still favours heating first because it changes what your solar system actually needs to do. A pre-heat-pump home looks like a winter-heavy, evening-peaky load profile. A post-heat-pump home looks much flatter, which lets you size solar (and any future battery) far more accurately. Use the Are Solar Panels Worth It in NZ? framework to model the two scenarios before committing.

The Eco-Conscious Family

You want to reduce emissions and lock in low future running costs. Heat pumps deliver larger CO2-equivalent reductions per dollar because they displace either gas or inefficient electric heating, and they make the home healthier (warmer, drier, lower respiratory illness). Solar is the second layer, the one that turns your already-efficient home into a near-self-powered one. Both belong, the order is just heating first.

How They Stack: The Sequenced Plan

If your budget is $10k now and $10k in 18 months, here's the sequence that gets the most value:

1. Year 1: Heat pumps for the main living zone and the master bedroom (or a ducted system if budget and house layout allow). Add ceiling insulation top-ups if you're below R3.6. Switch your hot water cylinder timer to run between 11am and 3pm.
2. Months 6 to 12: Track your power bill. Note your new winter peak load. Watch what your daytime usage looks like now that heating is more efficient.
3. Year 2: Size and install solar based on your actual post-heat-pump consumption profile, not your old one. You'll likely need a smaller (and more cost-effective) array than the door-knocker would have quoted you.
4. Year 3 onwards: Consider a battery only if your retailer's buy-back rate genuinely justifies it (most don't, currently), or if you're on a dynamic tariff plan that rewards storage arbitrage.

This sequence often delivers a better total outcome than buying both at the same time, because the second purchase is informed by real data from the first.

Common Pitfalls: What Installers Won't Tell You

Both heat pump and solar industries have their share of dodgy practice. Here's what to watch for:

On the heat pump side

• Oversizing for kickbacks. Some installers spec a 7 kW unit when a 5 kW would do, because margins are higher. An oversized heat pump short-cycles, runs inefficiently, and wears out faster.
• "One heat pump heats the whole house" claims. Physics disagrees. Heat doesn't reliably travel around corners. You need a unit in each zone you want warm, or a properly designed ducted system.
• Bargain-bin brands with no NZ support. Stick with brands that have proper NZ service networks: Mitsubishi Electric, Daikin, Fujitsu, Panasonic, Toshiba. Consumer NZ's heat pump reviews are worth the membership.

On the solar side

• "Zero power bill forever" claims. Grid-tied solar without a battery cannot do this. It's mathematically impossible for evening and winter loads. Walk away from anyone who says otherwise.
• Quotes that ignore your daytime occupancy. A good installer asks when you're home. A bad one just sizes to your roof.
• Pushing a battery on a flat-rate plan. Batteries make sense on dynamic tariffs or in homes with poor buy-back rates. They don't always pay back; do the maths.
• Subscription "no upfront cost" deals. The SolarZero collapse taught us what can go wrong here. If you're considering this route, read our piece on subscription solar alternatives first.

Financing the Sequence

If cashflow is tight, the major banks (Westpac, ANZ, BNZ, Kiwibank) all offer green home loan top-ups at 0 to 1% interest for both heat pumps and solar, usually up to $80,000 combined, with repayment terms around 3 to 5 years. EECA has also published lists of eligible products through the Warmer Kiwi Homes programme for heating support, which is means-tested but generous if you qualify.

Rather than us quoting rates that will date, check what you qualify for using our Green Finance Qualifier Tool. A 0% loan on a heat pump that saves you $800 a year is, effectively, free money. Don't leave that on the table.

Frequently Asked Questions

Will a heat pump really save more than solar in winter?

Yes, in almost every NZ home running resistance or wood heating today. A heat pump's 3 to 4x efficiency multiplier applies to your single largest electricity use, and the saving lands in the months your bill is highest. Solar production in June and July across most of NZ is around 25 to 30% of the December peak.

Can I run my heat pump off my solar panels?

You can run a heat pump partly off solar during the day. In winter, when you need heating most, solar production is at its lowest, so most of your heat pump's draw will still come from the grid. This is exactly why heating efficiency matters first: less grid draw to start with.

What if I already have heat pumps? Should I go solar now?

Quite possibly, yes. If your home is already efficiently heated and well-insulated, you've harvested the easy savings already. Solar becomes the next logical layer, especially if you have daytime loads or an EV. Use our solar worth-it framework to test the numbers for your situation.

Is a $10k solar system big enough to make a difference?

A 5 kW system at around $10k installed is the typical Kiwi sweet spot and will meaningfully offset your bill, especially if you're home during the day or have an EV. It won't wipe out the bill entirely, but a 30 to 50% annual reduction is realistic for the right household.

What about a wood burner? Should I keep mine?

If you have a free wood supply and don't mind the chainsaw, a modern compliant wood burner is genuinely cost-effective for the main living area. Many Kiwi homes pair a wood burner downstairs with a heat pump upstairs or in bedrooms. Solar then becomes about offsetting hot water, cooking, and appliances.

Does insulation matter more than either?

For older homes (pre-2008), ceiling and underfloor insulation should arguably come before either heat pump or solar. EECA's Warmer Kiwi Homes scheme can co-fund this for eligible households. A poorly insulated home is a leaky bucket and no heating system fixes that.

What about hot water heat pumps?

A hot water heat pump (sometimes called a heat pump hot water cylinder) is a serious contender for the "next $5k" question. They cut hot water energy use by 60 to 70% versus a standard electric cylinder. If your hot water bill is large, this is an underrated third upgrade after space heating and before solar.

If I do solar first and then heat pumps, what's the downside?

You'll likely over-size the solar array because you sized it to your old, inefficient consumption profile. That means more panels than you needed and a longer payback. It's not a disaster, but you'd have spent less money for the same outcome by reversing the order.

Where to Go From Here

The honest summary: in most Kiwi homes, heating efficiency is the higher-yield first dollar, and solar is the strong second dollar once you know what your home actually needs. Insulation underpins both. Don't let anyone rush you into reversing that order on the basis of a glossy quote.

If you want to dig deeper into the financial side, our true cost of going solar pillar walks through every variable that affects your payback. For per-watt installation pricing, see the current cost per watt for NZ installations. And when you're ready to get real quotes from people who won't try to sell you a battery you don't need, we can match you with vetted local installers below.