About 40% of Australian dwellings have rooftop PV, which is the highest rate in the world. Australia generates more solar electricity per person than any other country, from rooftop PV and solar farms.
A fully installed 10 kW system in Australia costs around $10,000 and lasts about 20 years. For many homeowners, the required rate of return on investing in rooftop PV is the house mortgage rate (6%), which equates to a tax-free real interest rate of about 2% after subtracting inflation. Real world annual output is approximately 1,300 kWh/kW per year.
These numbers translate to $0.05/kWh, which is far below retail tariffs.
Australian rooftop PV is much cheaper than in most countries. Reasons include the large scale of the industry, high skill levels, the absence of tariffs on Chinese solar panels, and Government regulations that are highly standardized and very smooth. Solar companies spend very little on advertising – rooftop PV is visible everywhere, which is its own advertisement.
The fraction of dwellings with rooftop PV is increasing by about 3% (absolute) per year. Many older systems are being upgraded. New rooftop PV systems have an average size of 11 kW. Many years ago, rooftop PV was kick-started by subsidies and attractive feed-in tariffs. Now it is driven by its compelling economic advantage.
In South Australia, the number of dwellings with rooftop PV has passed 50%, which means that half the population enjoys low electricity prices. Rooftop PV provides one quarter of annual electricity demand. It exceeds 100% of demand on sunny days, with the balance being exported eastwards. The grid remains very stable. South Australia is tracking towards 100% of its electricity from solar and wind on average in 2027. The wholesale spot market prices (corrected for inflation) is unchanged in the past decade.
Rooftop PV unlocks private money to produce vast amounts of clean electricity for houses, businesses and the grid. Government support is not required once the industry gets going. The grid remains highly stable even with high fractions of rooftop PV. Other countries can study Australian deployment methods and low-friction regulations.
An all-electric home has zero bill for natural gas or vehicle fuel. Energy storage is available in heat-pump hot water storage tanks (10-15 kWh), home batteries (10-40 kWh), and EV batteries (40-80 kWh). Simple timers can move operation of storage-charging, dishwashers, clothes washing & drying and house pre-heating & pre-cooling (via heat pumps) to daytime.
Rooftop solar combined with storage allows high energy resilience. If grid power fails, then the homeowner can carry on indefinitely with nearly normal house operation.
Uptake of EVs and heat pumps for water & space heating/cooling is starting to take off, strongly driven by the latest war in the Middle East.
Recently, the Australian Government implemented a very successful program to encourage the uptake of large (10-40 kWh) home batteries, usually coupled with new or expanded rooftop PV. Although the installed cost is quite high (around $350/kWh) and the payback period is long, many people enjoy the feeling of energy independence, and resilience if the grid goes down. Currently, about 3% (absolute) per year of Australian dwellings are installing home batteries.
Rooftop solar in Australia provides the cheapest, cleanest and most reliable domestic energy in history.
Authors: Prof. Ricardo Rüther (UFSC), Prof. Andrew Blakers /ANU
ISES, the International Solar Energy Society is a UN-accredited membership NGO founded in 1954 working towards a world with 100% renewable energy for all, used efficiently and wisely.
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