A solar hot water system uses specially designed collector panels to convert sunlight into heat for hot water. Water is cycled between the solar collector, which is situated out in the sun on the roof of the building, and a storage tank.

The storage tank can be installed on the roof of the building with the collector, or situated inside the building to reduce visual impact. Water is heated as it passes through the collector and returned as hot water to the storage tank.

To ensure adequate hot water at night or on overcast days, solar hot water systems are 'boosted' with either an electric or gas heater. For gas boosted systems, two types of solar collectors are available for selection:

  • flat plate collectors
  • evacuated tubes

Only one selection is available for electric boosted systems regardless of the type of solar collectors.

You will need to nominate the number Small-scale Technology Certificates (STCs - previously known as Renewable Energy Certificates, RECs) of the solar hot water system.

Note: From 1 January 2011 RECs were split into two types: small-scale technology certificates (STCs) and large-scale generation certificates (LGCs). RECs is still used as a general term covering both STCs and LGCs. STCs apply to domestic solar hot water systems, but some BASIX certificates may still refer to the term RECs.

In some instances, you may find that the BASIX energy score decreases slightly as you increase the STCs of a solar hot water system. Calculations of STCs in BASIX follow the relevant Australian standards and calculation methodology. The methodology generally associates a larger system with higher hot water output and a higher STC.

For houses with lower hot water demand, increasing the STCs may in some cases result in a reduction in energy efficiency of the hot water system, as the system is overdesigned for the likely hot water demand, resulting in a decrease in energy score.