Solar hot water in Australia

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Solar hot water refers to water heated by solar energy, a renewable energy source derived from the sun. This process involves thermal collectors, often called solar panels, which absorb solar energy to increase the temperature of the water. The heated water is then stored in a reservoir tank for future use. Solar hot water systems are utilised for a variety of purposes, including domestic and commercial water heating, contributing to heating and cooling systems, and providing process heat for industrial applications.

In residential settings, solar hot water systems are typically installed in one of two configurations. The "close-coupled" or "thermosiphon" setup integrates the thermal collectors with the hot water storage tank on a rooftop, allowing heated water to rise naturally into the tank. Alternatively, the "split system" separates the thermal collectors from the storage tank, requiring a pump to circulate water between the collectors and the tank. This configuration provides more flexibility in system placement and is often used when roof strength or aesthetics are considerations.^[1]

Solar hot water systems are designed to reduce energy consumption, a significant source of greenhouse gas and carbon emissions; If the state of Victoria switched from electric to solar hot water, Australia's total greenhouse gas emissions would be cut by 20%.^[2]

The penetration of solar water heaters in the Australian domestic market is at about 4% or 5%, with new dwellings accounting for most of the sales.^[3][4]

During the 1950s, Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) carried out world leading research into flat plate solar water heaters.^[5] A solar water heater manufacturing industry was subsequently established in Australia and a large proportion of the manufactured product was exported. Four of the original companies are still in business and the manufacturing base has now expanded to 24 companies.

Heating of water is the largest single source of greenhouse gas emissions from the average Australian home, accounting for around 28% of home energy use (excluding private vehicles). The Australian government estimates that installing a climate-friendly solar-powered hot water system could help households save $300 to $700 of electricity bills each year.^[6]