Enabling change in our Society, Environment and Economy (SEE)

Solar system answers

Courtesy of Peter Masters from the Anglican Church and updated in February 2011 by Ray Prowse, SEE-Change Member

There are two types of solar systems which are used on houses; solar water heating systems (which are not discussed in this article) and rooftop solar electric systems. Rooftop solar electric systems comprise photovoltaic (PV) panels (sometimes called modules) which produce direct current (DC) electricity when the sun shines on them. The DC electricity is converted into alternating current (AC) electricity by an electronic device called an inverter.

The resulting 240 volt electricity can either be used in the house or fed back to the local electricity grid. Most systems feed the electricity back to the grid during the day and take electricity from the grid at night, or when there are clouds.

Federal, state and territory governments recognise the environmental benefits of producing electricity without releasing the greenhouse gases produced when fossil fuels (generally coal) are burnt in power stations. As a result governments have been offering rebates to consumers who install such systems.

However government assistance has changed. They no longer offer rebates but have initiated a scheme where the installation of a photovoltaic system results in the creation of renewable energy certificates (RECs). These certificates are tradeable with the value dependent on market demand.

A rooftop photovoltaic system produces renewable energy certificates dependent on how much electricity it produces on an annual basis. The amount of electricity produced depends on two main factors:

  • size — the larger the system the more electricity it will produce
  • the amount of sun which shines on the photovoltaic panels. This, in turn, depends on the location of the system, the sunnier the location the greater output the panels will have, as well as the orientation (which way they are facing) and the inclination (tilt) of the panels.

The amount of electricity a system produces is measured in kilowatt hours (kWh) or megawatt hours (MWh). Over time a system will produce more and more electricity. Over a year it may produce several megawatt hours of electricity.

One renewable energy certificate is equivalent to 1 MWh of electricity per year.

A greater use of solar energy technologies reduces the need to construct and use even more fossil fuel power stations.

Rooftop photovoltaic systems, along with wind energy systems and all other systems using environmentally benign technologies, are starting to make a contribution to the energy mix in today’s society. They are being taken seriously and the industries are maturing through the assistance provided by such schemes as renewable energy certificates and small-scale technology certificates.

No one said switching to green was going to be inexpensive but can we afford not to?

For more information about RECs visit: www.cleanenergyregulator.gov.au/OSR/REC/The-REC-Registry

With thanks to our


  • ACT Government Environment and Planning
  • The Association of Independent Schools of the ACT (AISACT)
  • Catholic Education Office (Archdiocese of Canberra and Goulburn)
  • Education and Training Directorate
  • ACT Government