Not everywhere in Australia, you don't have to fit them but your home needs to meet a mandated minimum '6 star' energy rating. This comes down to everything in

Not everywhere in Australia, you don't have to fit them but your home needs to meet a mandated minimum '6 star' energy rating. This comes down to everything in the house such as wattage per square meter of lighting, double glazing in windows etc. The biggest pitfalls here usually with solar hot water is the storage capacity, especially with a family.