Note that this standard has been updated and you will need to meet the requirements set out in Australian New Zealand Standard AS/NZS 4234:2021 Heated Water Systems - Calculation of Energy Consumption.
You will be required to comply with this standard if you are a plumber and supply or install solar water heaters in Class 1 residential buildings such as sole occupancy homes and guest houses.
This standard sets out a method of evaluating the annual energy performance of water heaters using a combination of test results for component performance and a mathematical model to determine the standardized annual purchased energy use. The procedure is applicable to electric, gas and solar water heaters with integral boosting or preheating into a conventional storage or instantaneous water heater and to heat pump water heaters. For solar and heat pump water heaters, displaced purchased energy relative to reference water heaters is also calculated.