Solar Installations

The Acceptable Solution for Solar Water Heaters G12 / AS2 provides one way of meeting the performance standards of the NZ Building Code when specifying and installing a solar water heater. There is also the MBIE guidance on installing solar water heaters.

PLEASE NOTE: The Acceptable Solution does not cover installation of a water tank on the roof and some other installation situations. It is up to the supplier or installer to provide adequate proof that the system and its mounting arrangements will meet the performance standards of the Building Code.

Most roofs are designed to carry minimal additional loads. Therefore the Acceptable Solution places limits on the load density (22 kg per m²) and the size (4 m² of the roof), i.e. 88kgs over 4 m² of the roof. If a heavier or larger panel is proposed, then you will have to employ an engineer to assess the roof structure and to calculate how much additional load the roof structure can carry.

In some situations, a solar panel may need to be elevated above the roof surface either to maximise its efficiency (angle to the sun) or to allow the roof cladding to be washed by rain or accessed for cleaning (roofing warranty requirement). The accumulation of dirt and debris can lead to corrosion of metal roof claddings. The supplier or installer needs to provide adequate proof that system and mounting arrangements can cope with the additional wind loading and meets material maintenance (durability) and performance standards.

Penetration of metal roof cladding with pipes plumbed to the solar panel can result in corrosion of the roof cladding, if the metals touching each other are incompatible, resulting in leaks and allowing water into the building. Refer to the Consumer article Metal Roofs and the BRANZ article Roofing which cover roof penetrations and material compatibilities.