Guide
Estimate AU$ cooling cost before changing solar, batteries, or thermostat settings.
Australian air conditioning cost is mainly a summer-runtime problem. A reverse-cycle split system can be efficient, but long hot spells, duct losses, poor insulation, and high retailer tariffs can still push cooling into the largest household load. Estimate kWh first, then decide whether solar, shading, insulation, or tariff changes are the next step.
Solar ROI Explained
Electricity rates
Australian Energy Market Operator (AEMO)
Use your retailer bill first; cents/kWh varies across NSW, VIC, QLD, SA, WA, TAS, ACT, and NT.
Appliance efficiency
Energy Rating Label
Use rated cooling capacity and COP or seasonal efficiency where available.
Climate context
BOM and AEMO demand data
Summer cooling demand varies sharply by state, heatwave exposure, and home insulation.
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The Energy Rating Label and product datasheet are better than guesses because they separate cooling capacity from electrical input and efficiency. If the label lists COP or seasonal efficiency, use it. If it lists input power, use that as a cross-check against the calculator result.
A 3.5 kW reverse-cycle split system at COP 3.5 uses about 1.0 kW while running. At 30c/kWh, six running hours costs about AU$1.80. Over a 120-day hot season, that is roughly AU$216 before supply charges and other household loads.
Annual household kWh can hide the AC problem. In QLD, NSW, SA, WA, and NT, summer cooling can dominate monthly demand. In VIC, TAS, and the ACT, reverse-cycle systems may matter in both summer cooling and winter heating. Model hot-period runtime separately before sizing solar.
Air conditioning often runs during daylight, so rooftop solar can offset part of the load directly. Evening cooling still imports from the grid unless battery storage, pre-cooling, or tariff timing changes the usage pattern. Use the AC result as a load input before trusting solar ROI.
Check ceiling insulation, external shading, filter cleaning, duct sealing, thermostat setpoint, and zoning. In many Australian homes, reducing heat gain can lower runtime more than buying a larger unit.
Open the AC Running Cost Calculator