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:
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.
Including daylight saving, so a peak export window from 5 to 9pm is valued correctly in July and in January.
Median quoted prices per watt from 279 New Zealand quotes, and buy-back rates published by 10 retailers.
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.
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