As no official rating scheme is available for heat pump water heaters or solar gas or electric water heaters, these types of water heaters can be eligible to generate Small-scale Technology Certificates (STCs) under Australia’s Renewable Energy Target. The number of STCs is required as an input in NatHERS Whole of Home assessment and the number of STCs for many products is available on Clean Energy Regulator’s website. Note that the STCs calculator shall not be used for NatHERS Whole of Home assessment as its results are not calculated based on a 10-year use.