Get quotes

Solar tools

Free solar calculators for Canterbury homes

Three tools for the three big questions. Each one runs in your browser on PVGIS solar data for Canterbury and models every hour of the day, so it can tell the solar you use apart from the solar you export.

Will solar pay off for my house?

Solar savings and sizing calculator

  • Monthly output and how much you would use at home
  • Payback with or without a battery, EV or hot water diverter
  • Green loan repayments
  • The system size that pays back fastest
Open the calculator

Which power plan should I be on?

Buy-back plan comparer

  • Values your exports on 16 retailer plans, hour by hour
  • Peak-time and winter-only rates counted properly
  • Add import prices to rank by total bill
Compare plans

Is this quote any good?

Solar quote checker

  • Price per watt against 2026 median quotes
  • Tests the output, savings and payback claims
  • Lists the questions to send the installer
Check a quote

What makes these different

Most solar calculators multiply a year’s output by your power price. That treats every kWh as if you use it at home, when exported power earns a buy-back rate that is usually a third of what you pay. Ours split the two by modelling when your panels produce and when your household uses power, using:

Real Canterbury solar data

Monthly output from PVGIS 5.3, the European Commission’s solar model, run for Christchurch, Rolleston, Rangiora, Kaikōura, Ashburton, Timaru and Akaroa. It is the same data behind our Christchurch and Canterbury solar output page.

The sun’s path, hour by hour

Including daylight saving, so a peak export window from 5 to 9pm is valued correctly in July and in January.

Current 2026 prices

Median quoted prices per watt from 279 New Zealand quotes, and buy-back rates published by 10 retailers.

Every assumption on the page

With a way to change it.

For the background, read our guides to solar panel costs, sizing a system, buy-back rates and whether to add a battery.

Free, no-obligation quotes

Ready to compare real quotes?

We pass your details to installers who work in your part of Canterbury. If you used a calculator, its summary goes with your request.

Get my free quotes