Guide to the Kiwibank Sustainable Energy Loan

Kiwibank's Sustainable Energy Loan lets existing home loan customers borrow up to $80,000 at 1% per annum, fixed for three years, to put towards solar panels, batteries, EV chargers and other approved energy upgrades. That 1% rate is the headline, and it is genuinely good: when a typical floating mortgage rate sits well above 6%, borrowing for a $10,000-$12,000 solar system at 1% turns the finance question from "can I afford this?" into "why wouldn't I?" for a lot of households. The catch is that it is not free money, it is not a grant, and you have to already bank your mortgage with Kiwibank to get it. Here is exactly how it works, what qualifies, how to apply, and where the maths quietly falls down for some people.

Why a 1% loan changes the solar conversation

For most New Zealand homeowners, the single biggest barrier to going solar isn't doubt about whether it works. It's the upfront cost. A fully installed 5kW system runs roughly $9,000 to $13,000 in 2025, and a system with a decent battery can push past $20,000.

When you pay for that with normal savings or a top-up on your mortgage at standard rates, the interest quietly eats into your savings. Pay 6.5% interest on $12,000 over several years and you've added thousands of dollars to the true cost of the system. That's the number installers rarely put in front of you.

A 1% rate flips that. The interest becomes almost a rounding error against the power bill savings, which means the panels start paying for themselves from close to day one. If you want to see how finance changes the payback picture in detail, we walk through the full cost-and-return maths over here: the true cost of going solar in NZ.

What the Kiwibank Sustainable Energy Loan actually is

Kiwibank was the first major New Zealand bank to offer low-rate sustainable lending tied to home loans, and the scheme has become one of the better-known green finance options in the country. It is not a standalone personal loan. It is a top-up that sits alongside your existing Kiwibank home loan.

The key terms, per Kiwibank's published product details:

• Rate: 1% per annum, fixed.
• Fixed term: three years at that 1% rate.
• Borrowing limit: up to $80,000 across eligible purposes.
• Eligibility: you must have an existing Kiwibank home loan, and the property and lending need to meet Kiwibank's standard criteria.
• Repayment: structured like a home loan top-up, with regular principal and interest payments.

Most of the big New Zealand banks now run a version of green or sustainable lending, but the specifics differ a lot on rate, term and limit. Kiwibank's offer is competitive precisely because of that flat 1% fixed for three years. To compare what you might qualify for across lenders before you commit, our green finance qualifier tool is the quickest way to get a feel for it.

What you can spend it on

The loan is designed for upgrades that improve a home's energy efficiency or generate clean energy. For solar households, that typically covers:

• Solar panel systems and the inverter.
• Home batteries for storing your own generation.
• EV chargers installed at the property.
• Often heat pumps, insulation and efficient hot water systems, which pair beautifully with solar.

That last point matters more than people realise. The whole reason an under-insulated 1960s weatherboard place in, say, Mount Eden or Lower Hutt struggles in winter is that the heat leaks straight out. Solar feeds power in during the day, but if the house can't hold warmth, your heat pump runs harder. Bundling insulation and a heat pump into the same low-rate loan as your panels is one of the smartest moves available, and it's a genuine advantage of a broad sustainable energy loan over a solar-only finance deal.

The three-year term is the bit nobody explains properly

Here is the detail that quietly catches people out, and it's worth slowing down for.

The 1% rate is fixed for three years. The loan amount is often larger than you can comfortably repay in three years. So at the end of that fixed period, whatever is left rolls onto Kiwibank's standard home loan rates, the same rates as the rest of your mortgage.

This is not a trick, and Kiwibank is upfront about it. But the way you set up your repayments inside those three years makes a real dollar difference. You have two broad choices:

• Pay it off aggressively within three years. You squeeze maximum value from the 1% rate, because almost none of the balance ever touches a normal interest rate. This is the move if your budget can handle it.
• Pay it like a normal home loan top-up. Lower monthly payments, but a meaningful chunk of the balance rolls onto standard rates after year three, and you lose some of the benefit.

A worked example

Say you borrow $12,000 for a solar system on a home in Christchurch (Orion network territory).

At 1% over three years, the interest you'd pay across the whole term is only around $190. Compare that to financing the same $12,000 at a standard floating rate of roughly 6.5%: you'd be looking at well over $1,200 in interest across three years, and more if you stretch the term.

That difference, somewhere north of $1,000 in saved interest, is effectively a discount on your system that has nothing to do with the panels themselves. It comes purely from the financing. That's why the loan is worth understanding properly rather than just nodding along to whatever an installer's preferred finance partner offers.

And here's the part installers don't volunteer: a third-party finance company arranging "interest-free" or low-rate solar finance will often bake their funding cost into a higher system price. A 1% bank loan against your own mortgage doesn't, because the lending and the purchase are separate. Always get the cash price of the system first, then arrange finance, never the other way around.

How to apply, step by step

The process is more straightforward than people expect, but it pays to do it in the right order so you're not scrambling.

1. Get your solar quotes first

You need a real, itemised quote before the bank can do much. Get at least three so you can compare like for like on system size, panel and inverter brands, warranties and price. If you'd rather skip the cold-calling, we'll line you up with three quotes from installers we've vetted ourselves.

Make sure each quote clearly states the cash price, the system size in kW, and what's included. A useful sanity check on whether you're being quoted fairly is the current cost per watt for NZ installations, which tells you instantly whether a quote is in the right ballpark.

2. Check you meet the basics

You'll need an existing Kiwibank home loan and enough equity and serviceability for the top-up. If your mortgage is with another bank, you'd either need to refinance to Kiwibank (a bigger decision) or look at the equivalent green lending from your current bank.

3. Talk to Kiwibank

Approach Kiwibank directly, either through your existing mortgage contact or their home loan team, and tell them you want to use the Sustainable Energy Loan for a solar install. They'll confirm eligibility, the amount, and how it slots alongside your current lending.

4. Provide your quote and documentation

Kiwibank will want to see what the money is for. Your itemised installer quote is usually the core document. They may ask for evidence the work qualifies as an eligible sustainable upgrade.

5. Set up your repayment structure deliberately

This is where you protect that 1% advantage. Ask explicitly how to structure repayments so you clear as much as possible within the three-year fixed window. Don't leave it on autopilot.

6. Pay the installer and book the job

Once the lending is drawn down, you pay your installer as per their payment schedule. A fair installer takes a deposit, not the full amount upfront, with the balance on commissioning and sign-off.

Where the maths quietly doesn't work

Honest part. A low-rate loan makes solar more accessible, but it does not make a bad solar decision a good one. Low-cost finance on a system that was never going to pay off just means you owe money on something that underdelivers.

Think hard before borrowing if:

• You're out of the house all day with nobody home. Solar pays best when you use the power as you generate it. If your home sits empty from 8am to 6pm and you haven't got a battery or a load you can shift (hot water, EV, pool pump) into daylight hours, your self-consumption is low and your savings shrink. Buy-back rates from retailers are far lower than what you pay to buy power back, so exporting everything is the weakest outcome.
• Your roof is genuinely shaded. A poplar over the north face, a two-storey neighbour to the west, a chimney casting a long shadow: shading kills output disproportionately. No finance rate fixes a roof that can't see the sun.
• You're planning to move within a couple of years. Solar can add value, but you may not recoup the full cost on sale, and you'll have a loan to settle.
• You're a renter. The loan needs your own home loan, so this isn't an option, and the savings would flow to a property you don't own anyway.

If you're still genuinely weighing up whether the whole thing stacks up for your household, that's the right instinct. We work through it properly in are solar panels worth it in NZ, including the situations where the answer is honestly "not yet".

Buying outright versus a 1% loan

If you have the cash sitting in the bank earning interest, the comparison is closer than the 1% headline suggests. Money in a term deposit might earn you a few percent before tax. Borrowing at 1% while keeping your savings invested can leave you slightly ahead, depending on your deposit rate and tax position.

But for most households the real value of the loan isn't financial arbitrage. It's that it lets you go solar now, start saving on power immediately, and keep your emergency buffer intact rather than draining it. That's a sensible, conservative use of low-cost credit, which is exactly the kind kaitiakitanga-minded households tend to appreciate: doing the right thing for the long term without overextending.

What about subscription and zero-upfront models?

You may have seen solar offered with no upfront cost at all, as a subscription or lease. These can suit people who can't or don't want to take on debt or own the hardware. But the economics are different, and the collapse of one of the best-known providers reshaped that part of the market. We unpack what changed and what the alternatives look like in zero upfront cost solar: what happened to SolarZero.

For most homeowners with a Kiwibank mortgage and reasonable equity, owning the system outright with a 1% loan behind it is the cleaner, lower-cost long-run option than any subscription, because you own the asset and the savings.

Frequently asked questions

Do I have to bank with Kiwibank to get the Sustainable Energy Loan?

Yes. It's a top-up tied to an existing Kiwibank home loan, not a standalone personal loan. If your mortgage is elsewhere, you'd need to refinance to Kiwibank or look at the green lending your own bank offers. Several major New Zealand banks now run a similar low-rate sustainable lending product, though the rates and terms differ.

Is the 1% rate really fixed for the whole loan?

The 1% rate is fixed for three years. After that, any remaining balance moves onto Kiwibank's standard home loan rates. That's why structuring your repayments to clear as much as possible within the three years is the single most valuable thing you can do with this loan.

How much can I borrow?

Up to $80,000 across eligible sustainable upgrades, subject to Kiwibank's standard lending criteria, your equity and your ability to service the repayments. A typical residential solar install uses only a fraction of that, which leaves room to bundle in a battery, insulation or a heat pump.

Can I use it for a battery and EV charger, not just panels?

Yes. Batteries, EV chargers, heat pumps, insulation and efficient hot water systems generally qualify alongside solar. Bundling complementary upgrades into one low-rate loan is one of the most sensible uses of it, especially for an older, under-insulated home.

Will the loan cover the whole cost of my system?

It can, up to the borrowing limit and subject to approval. But you should always establish the cash price of your system first and finance second, so you can tell whether a quote is fair before any finance is layered on top.

Does the loan affect my solar warranty?

No. The loan is between you and the bank; your panel, inverter and workmanship warranties sit with the manufacturers and installer regardless of how you pay. Just make sure the warranties themselves are solid and in writing before you sign anything.

Is this the same as a government grant or subsidy?

No. There's no national solar grant for general homeowners in New Zealand. This is a low-interest loan, meaning you repay every dollar plus a small amount of interest. The benefit is the low-cost financing, not free money.

Should I pay cash if I have it instead of borrowing?

It depends on what your cash would otherwise earn and your tax position. Borrowing at 1% while leaving savings invested can leave you marginally ahead, and it keeps your emergency buffer intact. For many households that flexibility is worth more than the small numbers either way.

The bottom line

The Kiwibank Sustainable Energy Loan is one of the genuinely good deals in New Zealand solar finance: 1% fixed for three years, up to $80,000, for households that already bank their mortgage with Kiwibank. Used well, it strips most of the financing cost out of going solar and lets you start saving on power without draining your savings.

The two things to get right are simple. Nail down the cash price of a properly specced system before you talk finance, and structure your repayments to clear the balance inside the three-year window. Do both, and the loan does exactly what it's meant to.

If you're at the stage of pinning down real numbers, the smart next move is to get accurate quotes for your roof, then run them past the green finance qualifier to see what financing you'd actually qualify for.