This calculator helps New Zealand homeowners work out how long a solar panel system would take to pay for itself through reduced power bills, and what it could save over its lifetime. You enter the system cost, your power usage and tariff, and an estimate of how much of the solar generation you would use yourself versus export, and the tool projects the annual savings and the payback period. The breakdown shows the upfront cost, the yearly savings, the break-even point, and the long-term benefit, helping homeowners decide whether solar makes financial sense for their situation rather than relying on optimistic sales figures, with prices and tariffs used as inputs to keep it current.
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.
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.
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.
If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.
Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.
All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.
Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.
Calculate.co.nz is also partnered with Health Based Building and Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.
Calculate.co.nz is hosted in Auckland via SiteHost new Zealand.
All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.
© 2019 to 2026 Calculate.co.nz. All rights reserved.