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Solar water heating

Technical information for solar installers, including the Plumbers' Journal technical series.

Compliance | G12/AS2 | Satisfying the purchaser | Building consents | Code of practice | Standards | Grants scheme | Templates | Articles | Publications

Hot water is one of the biggest users of household energy. It accounts for between 30% and 45% of total household energy use. A solar water heating system can provide homeowners with 50% to 75% of their yearly hot water needs, cutting annual power bills.

Compliance

Solar installers need to be aware of the following compliance issues:

  • Plumbers, Gasfitters and Drainlayers Act: all sanitary plumbing must be carried out by licenced plumbers under the direction of a certifying plumber - including the connection of water to and from any solar water heater supplying more than one sanitary fitting or appliance.
  • NZBC clause G12: specifies performance requirements relevant to the water supply aspects of the system - and G12/AS2 is the Acceptable Solution for solar water heating (see below).
  • Electrical connections: connections to permanent wiring must be carried out by a licensed electrician or a solar water heater installer who holds an associated tradesperson's electrical work certificate.
  • Gas work: must be carried out under the direction of, and certified by, a certifying gasfitter.

G12/AS2

Acceptable Solution G12/AS2 sets out what a solar water heater installer has to do to comply with the Building Code.

It specifies one way to achieve compliance with all relevant Building Code clauses in a single document and simplifies the consent process, allowing consents to be processed more quickly.

While G12/AS2 it makes it easier to design a solar water heating installation, it is limited in its application. It covers installations where panels are up to 4 m2 in area and weigh no more than 22 kg/m2. The design allows for wind speeds up to 50 m/s (180 km/h) and applies only where the roof pitch is less than 45°. If the installation does not meet these criteria, the building consent authority will require a detailed structural design to be undertaken.

G12/AS2 can be downloaded free from the DBH website within the G12 Compliance Document.

Satisfying the purchaser

As part of the Acceptable Solution for compliance, installers must ensure the purchaser of the solar water heating system is satisfied with the system.

To do this, the supplier/installer should:

  • carry out a site inspection with the purchaser prior to the sale
  • clarify all aspects of the system performance and installation
  • make written guarantees available
  • confirm in writing all the information discussed and the agreed installation aspects. This could consist of a simple check sheet recording the information, and signed by the supplier/installer and purchaser
  • give the purchaser a copy of the manufacturer's operating and maintenance instructions and written guarantees (guarantees should describe the responsibilities of the owner, supplier and installer). These should be kept in an obvious place in the property, for access by future owners
  • show copies of such documentation to the potential purchaser prior to purchase
  • give purchaser the names, addresses and signatures of the supplier and installer
  • give importer's contact details if the system is not NZ-made.

Building consents

A building consent is required for solar water heating system installations. The system installer needs to demonstrate that the installation will meet the NZ Building Code. The Code establishes the standards for installation, particularly for safe loading on roofs and safe supply of potable water.

  • A certifying plumber must submit a consent application to the TA/BCA to get approval for the installation of all components of the solar water heating system through which potable water flows. The whole installation will then be checked and certified by the building inspector.
  • Solar water heating systems can involve heavy loads on roof structures - and they must be installed in such as way as not to endanger the roof structure. A building consent may be needed for this. The installer should check with the local TA/BCA to confirm the requirements.
  • Consents must be obtained before installing the system.
  • The installer is responsible for ensuring compliance with consent conditions.

System suppliers may provide pre-prepared, supporting documentation to accompany a consent application. This should include acceptable structural support arrangements for the specific system models.

Acceptable Solution G12/AS2 sets out the requirements and standards for most solar water heating installations that, if followed, will facilitate the consent process. This applies to installations where the tank is not on the roof.

A number of councils are committed to zero consent fees for solar water heating in a bid to encourage homeowners to install solar water heating.

Code of Practice

  • The Code of Practice for Manufacturing and Installation of Solar Hot Water Systems in New Zealand (PDF, 1.4mb) has been prepared jointly by EECA and the Solar Association NZ (formerly the Solar Industries Association). It provides guidance on expected manufacturing and installation standards of solar hot water equipment in NZ. SWH installers should use it to ensure they are aware of installation requirements expected by the industry. The Code is continually evolving. Any issues, comments or suggested modifications are welcomed.

Standards

Solar water heating installers need to be aware of the following Standards.

  • AS/NZS 2712:2007 Solar and heat pump water heaters - Design and construction
  • AS/NZS 3500.0:2003 Plumbing and drainage - Glossary of terms
  • AS/NZS 3500.1:2003 Plumbing and drainage: Water services
  • AS/NZS 3500.4:2003 Plumbing and drainage: Heated water services
  • AS/NZS 3500.5:2012: Plumbing and drainage: Domestic installations
  • NZS 4305:1996 Energy efficiency - Domestic type hot water systems
  • NZS 4218:2004 Energy efficiency - Small building envelope
  • NZS 4613:1986 Domestic solar water heaters
  • NZS 4614:1986 Installation of domestic solar water heaters.

Master Plumbers members can purchase relevant online Standards at discounted prices through the Standards New Zealand Online Library Essentials catalogues.

Grants scheme

Energywise grants for solar water heating have come to an end. 

Templates

Templates you may wish to use or modify for your solar water heating business.

Articles

NZ Plumbers' Journal features a series on solar water heating installations, by Ian Sumner of EcoSolar, Energy Conscious Design and Splash Monitoring and Adrian Kerr of the Solar Association of New Zealand. Click on the links below to download the articles.

General articles on solar water heating that have appeared in Plumbers' Journal.

Publications