NZ Solar Guide
Guide to the BNZ Green Home Loan
Bottom line up front: BNZ's Green Home Loan lets eligible BNZ home loan customers borrow up to $80,000 at 1% p.a. fixed for three years to install solar panels, batteries, heat pumps, insulation, double glazing and other approved energy improvements. You can combine solar and battery in the same loan, the interest rate is well below standard mortgage rates, and you don't pay establishment fees on the top-up. The catch: you need to already hold (or be taking out) a BNZ home loan, the home needs to be owner-occupied, and the 1% rate resets to standard floating after the three-year fixed period ends. For most BNZ customers buying a 6.6 kW system with a battery, this is the most cost-effective finance available in New Zealand right now.
If you bank with BNZ and you're seriously considering solar, the Green Home Loan is one of the better-value finance products on the market in Aotearoa. But like any banking product, the headline rate doesn't tell the whole story. This guide walks through exactly how it works, what's covered, what's not, and how to think about combining a solar array with a battery inside a single application.
This article assumes you're a BNZ home loan customer (or about to be one). If you bank elsewhere, you'll want to compare with the equivalent products from Westpac, ANZ, Kiwibank and ASB through our Green Finance Qualifier Tool. The rules differ in important ways.
What the BNZ Green Home Loan Actually Is
The BNZ Green Home Loan is a top-up to your existing BNZ home loan, not a separate personal loan or hire purchase. That's the most important thing to understand, because it changes everything about how the product works in practice.
Because it sits on top of your mortgage, it's secured against the property, the interest rate is dramatically lower than an unsecured solar finance product, and the loan doesn't appear as a separate line item with separate fees. The bank treats it as part of your home lending.
According to BNZ's published product details, the key terms are:
- Maximum loan amount: $80,000
- Interest rate: 1% p.a. fixed for three years
- Establishment fee: Nil (no top-up fee charged on the green portion)
- Loan term: Repaid over a period to suit your existing home loan structure
- After 3 years: Reverts to BNZ's standard floating rate (or you can refix)
- Property: Must be owner-occupied; not available for pure investment properties under most circumstances
For comparison, BNZ's standard floating home loan rate has been sitting in the 7-8% range for most of 2024-2025. A 1% fixed rate represents a meaningful subsidy that the bank is willing to wear because it counts toward their sustainable lending targets.
Who is eligible?
To qualify, you generally need to:
- Have an existing BNZ home loan, or be taking one out as part of a property purchase or refinance
- Own and occupy the home where the improvements will be installed
- Have sufficient equity in the property (the bank will reassess your overall lending position)
- Use the funds on BNZ's approved list of energy-efficient improvements
This last point catches some people out. If you're currently with ASB or Kiwibank and you want the BNZ deal, you'll need to refinance your mortgage to BNZ. Whether that's worth it depends on your break fees and whether BNZ's standard rates are competitive at the time. Run the maths before you switch banks just for the green top-up.
What You Can Spend the Money On
BNZ's approved list covers most of the sensible energy improvements a Kiwi homeowner might want. For solar specifically, you can use the Green Home Loan to fund:
- Solar PV systems (panels, inverter, mounting, install labour)
- Home batteries (LiFePO4 systems like Tesla Powerwall, BYD, Sungrow SBR, Goodwe Lynx and similar)
- EV chargers (a fixed home charger, not a portable lead)
- Heat pumps (split systems, ducted, and hot water heat pumps)
- Insulation (ceiling, underfloor, wall)
- Double glazing or thermal window upgrades
- Hot water cylinder upgrades (heat pump or solar hot water)
- Ventilation systems
- Rainwater harvesting (in some cases)
The bank typically requires an invoice or quote from an accredited supplier or installer, and they may pay the installer directly rather than depositing the cash in your account. This protects everyone: the bank knows the money was spent on what you said it would be, and you don't have to front the cash before the work is done.
The MBIE Genless register
BNZ broadly aligns with EECA's Gen Less guidance and the MBIE-supported product categories for energy efficiency. If a product appears on the Genless or EECA-aligned approved list, you can be reasonably confident BNZ will fund it.
Combining Solar and Battery in One Loan
This is the question that brings most readers to this article: can I put a solar array and a battery on the same Green Home Loan? Yes, you can, and it's the most common use case among BNZ customers using this product.
Here's a realistic example for a Tauranga family looking at a quality install:
- 6.6 kW solar system, premium N-type TOPCon panels, hybrid inverter: $13,500
- 10 kWh LiFePO4 battery (BYD or Sungrow): $13,000
- Smart EV charger (Wallbox or Zappi): $2,200
- Ceiling insulation top-up: $2,500
- Total project: $31,200
That's well inside the $80,000 cap, all covered under one application, all at 1% p.a. for three years. The bank treats it as a single top-up to your mortgage, and the installer gets paid in one or two milestones (deposit and completion).
For exact pricing tailored to your roof, run the numbers through our current cost-per-watt guide for NZ solar installations, and to sanity-check whether the investment makes sense for your household, read Are Solar Panels Worth It in NZ?.
Why bundling matters for ROI
Bundling solar and battery in one finance package, at 1% rather than 7-8%, transforms the economics. The interest you'd otherwise pay on a standard top-up over three years can easily be $3,000 to $6,000 depending on the loan size. That saving alone can fund a meaningful chunk of your battery.
For the maths that ties this all together (system size, energy production, buy-back, finance cost, payback period), use our full guide to the true cost of going solar in NZ.
What This Means for You (by Persona)
The ROI Pragmatist
You're the natural fit for this product. A 1% fixed rate for three years on a solar-and-battery bundle is, in pure financial terms, almost certainly the most cost-effective finance you'll find for this kind of project in New Zealand. The payback maths improves dramatically when finance is this accessible.
Key question: what happens at month 37? The rate reverts to BNZ's standard floating, which has historically been 7-8%. Plan for that. You have three full years to either pay down the green portion aggressively or refix at whatever the prevailing home loan rate is at the time.
The Tech-Savvy Optimiser
You'll love that the loan covers the smart EV charger as well as the hybrid inverter and battery. That means you can finance a properly integrated system, the kind that lets you arbitrage dynamic time-of-use tariffs from retailers like Octopus Energy NZ or Ecotricity, at 1% cost of capital.
One nuance: BNZ generally funds the install, not the brand. So whether you choose a Tesla Powerwall 3, a BYD Battery-Box, a Sungrow SBR, or a Goodwe Lynx, the bank doesn't really mind. They want a tax invoice from an accredited installer. Pick the kit on its technical merits, not on what the bank prefers.
The Eco-Conscious Family
This product was practically designed for you. The whole point of BNZ's 1% rate is to remove the financial friction between Kiwi households and a lower-emissions home. You can do solar, battery, heat pump, insulation and double glazing all in a single $60,000-$80,000 application.
If you're already locked into a long fixed-rate home loan with BNZ, the green top-up generally sits alongside it without breaking your existing fix. Have a yarn with your BNZ banker about how it stacks on top of your current structure.
Common Pitfalls and What the Bank Won't Volunteer
The Green Home Loan is genuinely good value, but there are a few things worth understanding before you sign.
1. The rate is fixed for 3 years, then resets. Some homeowners read "1% interest" and assume that's the rate for the life of the loan. It isn't. After three years, you'll pay BNZ's standard floating rate (or you refix). Build your repayment plan around finishing the green portion within the three years if you can.
2. The loan still impacts your overall borrowing capacity. Even at 1%, this is debt secured against your property. If you're planning to borrow more later (say, for a renovation or a second property), the green top-up reduces the equity you have available. Banks will assess your total exposure, not just the "green bit".
3. You must use accredited suppliers. If you find a "mate of a mate" who'll do the install cash-in-hand for a discount, BNZ won't fund it. The product requires a tax invoice from a legitimate, accredited installer. This is a feature, not a bug; it protects you from cowboys.
4. Some installers quietly mark up prices for finance customers. This is the trust-proxy point. Always get three independent quotes before applying for finance. Some installers know you've got low-cost money lined up and will pad the quote accordingly. Compare quotes blind.
5. The product can change. Banks adjust green lending products in response to government incentives, Reserve Bank settings, and their own sustainability targets. The terms quoted here are accurate at time of writing, but always verify on BNZ's current Green Home Loan page or check our Green Finance Qualifier Tool for the latest position.
6. SolarZero refugees, read carefully. If you previously had a SolarZero subscription on your roof and you're now looking to buy your own system outright, the BNZ Green Home Loan can fund that. For the broader context on what to do post-SolarZero, see our guide for former SolarZero customers.
How to Apply: A Practical Walkthrough
The application is genuinely straightforward if you're already a BNZ customer. Here's the rough sequence:
- Get three solar quotes from accredited installers. Don't apply for finance before you've benchmarked pricing.
- Pick your preferred installer and get a formal quote with itemised costs (panels, inverter, battery, install labour, GST inclusive).
- Talk to your BNZ banker or apply online through your BNZ mobile app or the Green Home Loan portal.
- Provide the quote as evidence of intended use of funds.
- The bank assesses your overall position (existing home loan, equity, serviceability).
- Funds are typically released on milestones, often direct to the installer rather than into your account.
- Repayments start alongside your normal mortgage repayments.
From application to install completion, expect 4-8 weeks for most households. Solar installers in Auckland, Wellington and Christchurch are typically booking 4-6 weeks out, and the BNZ assessment itself rarely takes more than a fortnight if your finances are in good order.
Frequently Asked Questions
Can I get the BNZ Green Home Loan if I bank with a different bank?
Not directly. You'd need to refinance your home loan to BNZ. Whether that makes sense depends on your break fees, current rate, and BNZ's standard pricing at the time. For most people, it's not worth refinancing solely for the green top-up; the savings on $30,000 at 1% versus 7% for three years are real, but break fees can eat them.
What's the maximum I can borrow?
$80,000 in total under the green portion, provided your overall borrowing position supports it. Most residential solar-plus-battery projects come in well under that cap.
Is the 1% rate really fixed for the full 3 years?
Yes, the 1% p.a. is fixed for three years from drawdown. After that, the loan reverts to standard floating, or you can refix at the prevailing standard rate. There's no green renewal at 1%; the discount is a one-time three-year window.
Can I use it for an investment property?
Generally no, the product is structured for owner-occupied homes. There are some niche cases (e.g. a property you'll be moving into) where it may apply. Talk to BNZ directly for your specific situation.
Does the loan cover battery storage on its own, without solar?
Yes, batteries are an approved category in their own right. If you already have solar and you're adding storage later, the Green Home Loan can fund the battery and any associated electrical work.
What happens if I sell the house?
The Green Home Loan is part of your home lending, so it's typically repaid out of the sale proceeds along with your main mortgage. The solar system stays with the property and is generally treated as a value-add at sale time.
Can I combine the BNZ Green Home Loan with an EECA grant?
For residential solar, there isn't currently a direct EECA grant available to homeowners (most EECA support is targeted at low-income households, commercial users, or specific schemes). The Green Home Loan stands largely on its own as the main finance benefit for BNZ customers.
Is 1% really the best rate available in NZ?
At the time of writing, the major Australian-owned banks (BNZ, Westpac, ASB, ANZ) and Kiwibank all run green home loan products with rates between 0% and 1%. Terms, caps, and durations vary. Use our Green Finance Qualifier Tool to compare your eligibility across all of them.
What if I want to pay it off early?
You can generally make extra payments on the green portion without break fees, as long as you stay within the bank's lump-sum rules for fixed lending. Confirm specifics with your BNZ banker before assuming.
Where to Go From Here
The BNZ Green Home Loan is one of the more compelling reasons to actually pull the trigger on solar if you're a BNZ customer who's been thinking about it. At 1% p.a. fixed for three years, with no establishment fees, and a generous $80,000 cap that easily covers solar plus battery plus EV charger, the financial barrier to a properly specified system is the lowest it's been in a long time.
Your next moves, in order of usefulness:
- Check your eligibility across BNZ and the other major banks via our Green Finance Qualifier Tool.
- Get a realistic sense of system pricing with the current cost-per-watt guide.
- Read the full pillar on solar costs, finance, and ROI in NZ to see how all the pieces fit together.
- Then, when you're ready, get three independent quotes from vetted installers so you know the price you're financing is fair.
