Australia's Federal Government has developed a small-scale renewable energy scheme (SRES) to support residential and commercial properties generating less than 100kW of solar power.
This works by creating a small-scale Technology Certificate (STC) for solar panels installed from now until 2030. These certificates are tradable, and they vary in price based on supply and demand. In 2017 their price averaged around $34 — rising as high as $38 and falling as low as $28.
Depending where your live, different calculations are given. In 2017, in United Energy's zone (zone 4), a 5kW system typically generated 82 STC certificates, reducing the cost average by 82 x $35 ($2870) for each 5kW system installed. If you installed a 10kW system, the amount saved would have been $5740.
Each year, the amount reduces. In 2018, a 5kW system was expected to drop to 77 certificates produced.