What does it actually cost to run?

A bedroom split system rated at 2.5kW of cooling draws about 0.5kW of electricity, which is roughly 16 cents an hour at 32 c/kWh. A living-room unit rated at 5kW draws about 1.32kW, or around 42 cents an hour. A ducted system serving a whole house draws about 4kW flat out — close to $1.28 an hour — though it drops to a third of that once the house reaches temperature.

Because the number on the box is cooling capacity, not electricity consumption. An air conditioner moves heat rather than creating it, so it delivers three to five times more cooling than the power it draws. A unit sold as 5kW uses about 1.32kW of electricity. This is the single most common error in published appliance tables, and it overstates air-conditioner running costs by three to four times.

Over a year it is usually heating and cooling, which is around 40% of a typical Australian home's energy use. But the biggest single item on many bills is electric storage hot water, at roughly 8.5 kWh a day for a family — more than a fridge, a dishwasher and a television combined. In homes with a pool, the pump is often the second largest.

A single-speed pool pump drawing 1.1kW for eight hours a day uses about 8.8 kWh, which is roughly $2.82 a day or just over $1,000 a year at 32 c/kWh. That is commonly around 18% of the electricity bill in a house with a pool. A variable-speed pump doing the same job draws about 0.45kW and costs well under half as much.

No, and anyone telling you otherwise is overselling it. Power you use from your own roof costs you the feed-in tariff you gave up by not exporting it — a few cents per kWh rather than nothing. At a 5 c/kWh feed-in rate against a 32 c/kWh grid rate, you are still about 27 cents better off per kWh, which is where the real saving comes from. It only applies to the hours the appliance runs while the sun is up.

Dishwashers, washing machines, dryers, pool pumps, heat pump hot water and EV charging — anything whose timing you control. Moving those into daylight is the cheapest saving available to a solar owner because it costs nothing to do. The catch is electric storage hot water, which is often wired to an overnight controlled-load tariff, so solar never touches it until that is changed.