Solar Panel Payback Calculator NZ

This calculator estimates how many years a solar panel system takes to pay for itself in New Zealand, and what it could save you over a typical 25-year lifespan. You enter the installed system cost, the generation you expect per year in kilowatt-hours, the share of that generation you will use yourself rather than export, your power price per kilowatt-hour, and the export or buy-back rate your retailer pays for surplus power. The calculator splits your generation into self-used and exported portions, values each at the right rate, and adds them together for your annual saving. It then returns the payback period in years, the annual saving in dollars, the projected saving over 25 years, and the net benefit once the system cost is subtracted. Power you use yourself saves the full retail price, while exported power earns a lower buy-back rate, so the results depend heavily on how much generation you actually consume at home. Use a realistic self-use estimate rather than an optimistic sales figure, since that single number can shift the payback period by years. The figures ignore panel degradation and future changes in power prices or export rates, either of which could move the real payback earlier or later. Use it to sense-check installer quotes and compare systems on a like-for-like basis. This is an indicative estimate only, not financial or engineering advice.

Calculate.co.nz is proud to be partnered with Health Based Building, a leader in sustainable and health-conscious building innovation. With over a century of experience, they develop high-performance systems like Foreverbreathe Specification, Magnum Board, and Foreverbreathe Paints to support energy-efficient, non-toxic living environments. Their commitment to healthier homes aligns with our belief that informed choices lead to better outcomes for Kiwi households.
Calculate.co.nz partner: Health Based Building
Advertise on this page
$
%
$
$
10.0
years to pay back the system
Annual saving$1,200
Saving over 25 years$30,000
Net benefit (25y)$18,000

Power you use yourself saves the full retail price; exported power earns the lower buy-back rate, so self-use drives the savings. This ignores panel degradation and future price changes, which can move both ways. Use realistic figures rather than optimistic estimates. Estimate only, not financial advice.

How it works

The calculator splits your annual generation into the share you use yourself and the share you export. Self-used power saves you the full retail price you would otherwise pay, while exported power earns the buy-back rate your retailer offers, which is usually lower. Adding the two gives your annual saving. Dividing the system cost by that saving gives the payback period, and projecting the saving over 25 years shows the long-term benefit.

Worked example

A $12,000 system generating 6,000 kWh a year, with 50% self-used at 28 cents and 50% exported at 12 cents, saves about $840 from self-use plus $360 from export, roughly $1,200 a year. That pays back in about 10 years and saves around $30,000 over 25 years, a net benefit of about $18,000 before any price changes.

Related calculators

Frequently asked questions

How long does solar take to pay for itself in New Zealand?

It depends on the system cost, how much power it generates, how much you use yourself versus export, and your tariffs. Many systems pay back over several years; this calculator estimates the period for your situation.

Is it better to use solar power or export it?

Power you use yourself saves the full retail price, while exported power earns a usually lower buy-back rate. So the more of your generation you use directly, the faster solar pays back.

What affects solar savings?

System size and cost, your location and sunshine, how much you self-consume, your power price and the export rate all matter. Use realistic figures, as optimistic sales estimates can overstate the savings.