Choosing a Solar Hot Water System

The Cost

Purchase and installation costs of a commercial solar hot water system in a domestic residence are in the range of $4000 to $7000 depending on:

  • the size of the collector panels;  
  • the capacity of the cylinder; 
  • whether you are installing a new system or retrofitting an existing system;  
  • whether you connect into the existing hot water cylinder or not; and   
  • the degree of installation complexity, which depends on the building design.


The System

Only systems that have been independently vetted as complying with the New Zealand manufacturing and safety standards should be purchased. Other systems may or may not be safe or well manufactured. Unless independently vetted their suitability is untested.

In general complying systems will operate very similarly at different locations throughout New Zealand. The biggest difference will arise from the experience and capabilities of the installers. Using an Accredited Installer will assist in ensuring that the energy performance of the installed system is optimal.

There are however differences in system design that purchasers should address when choosing a system:

  • The means of control of supplementary heating
  • Design and configuration of hot water storage tank
  • Means of freeze protection
  • Means of avoiding excessive loss of water at times of very high solar heating


The Supplier

There are a number of suppliers of different solar hot water systems. Each system will have a number of different manufacturing and performance characteristics. To choose the system that meets your situation you may find this check list useful:

Does the supplier:

  • hold Accreditation for the Supply and Installation of SWH Systems from the Solar Association? Only Accredited Suppliers have been independently vetted as complying with the solar Code of Practice, which assists to ensure that their products have been tested and their service is satisfactory.   
  • have an Approved Installer in your area who has been trained by a product distributor or the Accredited Supplier and is experienced and familiar with their range of products. Can the Approved Installer show you documentation that shows that he/she is fully trained to install this distributor 's systems? More than 85% of solar performance issues are related to poor installation.  
  • provide you with satisfactory answers to your questions?  
  • provide you with a clear specification of what equipment they will provide, who will install it, the relationship with other trades people, access requirements, layout and installation aspects?  
  • provide you with good clear documentation of what energy performance you can expect from their system for your house design, location, direction, and for each of the seasons? For energy performance information click here.   
  • have a quality system for supply and installation that is demonstrable? (such as ISO9002)  
  • have a history of supplying and installing sound efficient systems?  
  • confirm that the system has been built and will be installed to the Solar Association Code of Practice?
  • undertaken to obtain the Building Consent required by your local Council. A Building Consent can be costly to obtain unless the Building Inspectors can be assured that the installer knows what they are doing and that it is actually done?  
  • have documentation (such as owner's manual) showing on-going maintenance requirements? 
  • have a design that will meet any frost, electricity supply interruptions, overheating safety events?  
  • provide a written guarantee?  
  • undertake to provide you with an owners manual after installation?  
  • have a record of being a sound business that is likely to be around to fulfil their guarantee obligations?  
  • provide references to other successful installations that you can follow up?  
  • have a price that is right for you?