Heat Pump Hot Water Running Costs: Real Numbers for 2026

The single biggest variable in heat pump running costs is what you pay for electricity. Australia has a wide range of tariff structures, and the right one can halve your hot water costs.

Standard flat rate (28-35c/kWh): Most households are on a flat rate tariff where you pay the same price per kWh regardless of time of day. At 30c/kWh with a COP-3.5 heat pump, annual hot water costs for a 4-person household are approximately $300-$400.

Time-of-use with off-peak (15-22c/kWh off-peak): Many retailers offer time-of-use tariffs with cheaper rates overnight (typically 10pm-7am) or during shoulder periods. If your heat pump runs primarily during off-peak hours, costs drop to approximately $150-$250/year. Most heat pumps have timers that make this easy to configure.

Controlled load / dedicated circuit (12-18c/kWh): Some retailers offer a dedicated "controlled load" tariff for hot water systems on a separate circuit. The retailer controls when the circuit is energised (typically overnight). This gives the lowest per-kWh rate but removes your control over timing. Costs: approximately $130-$200/year.

Solar self-consumption (0c/kWh): If you have rooftop solar and run your heat pump during daylight hours, the electricity is essentially free (you would otherwise export it for 4-8c/kWh). Costs: approximately $50-$100/year (for cloudy days and winter shortfall only).

The optimal strategy depends on whether you have solar panels:

If you have solar panels (3kW+): Run the heat pump during the day (10am-3pm). The marginal cost of solar self-consumption is near-zero, and you are using energy that would otherwise be exported at a low feed-in tariff (4-8c/kWh). This is the cheapest option by far. Annual cost: $50-$100.

If you do not have solar panels: Use off-peak or controlled load tariffs. Set the heat pump timer to run overnight when rates are lowest. Annual cost on off-peak: $150-$250.

The least efficient approach: Running the heat pump during peak tariff hours (3-9pm, typically 35-50c/kWh on time-of-use plans). This still costs less than gas, but significantly more than off-peak or solar. Annual cost on peak rates: $400-$550.

Electricity prices vary significantly across Australian states, which affects heat pump running costs.

In every state, heat pump running costs are 60-75% lower than gas storage. The savings are most dramatic in Victoria and South Australia, where gas prices are highest.

South Australia has the highest electricity prices, but its excellent solar resources mean that solar self-consumption can offset much of this. SA homeowners with solar panels can achieve among the lowest hot water costs in the country.

Hot water consumption scales with household size. Here are realistic annual running costs for heat pumps at standard flat-rate electricity (~30c/kWh, COP 3.5):

Larger households save more in absolute dollars, which means the payback period for a heat pump is actually shorter for bigger households. A 5-person household saving $750/year can pay back a $3,000 net investment (after rebates) in just 4 years.

Here is the complete picture, comparing all four hot water system types on a like-for-like basis for a 4-person household:

Heat pumps offer the best balance of low upfront cost, low running cost, and low emissions. Solar thermal has slightly lower running costs but is significantly more expensive to install and more complex to maintain (roof-mounted panels, glycol fluid, pumps).

Electric storage is cheapest to install but the most expensive to run, making it the worst long-term value. Gas storage will not be available as a replacement option in Victoria after May 2027.

Total cost of ownership (TCO) is the only fair way to compare hot water systems. Here is a 10-year scenario for a 4-person Melbourne household:

Heat pump (315L, after VIC rebates):

• Install cost (after rebates): $2,800
• Annual running cost: $320
• Maintenance (anode check x2): $300
• 10-year total: $6,300

Gas storage (170L, if it were still available):

• Install cost: $2,200
• Annual running cost: $950 (and rising ~5%/year with gas price increases)
• Maintenance (annual service): $800
• 10-year total: $13,500

Electric storage (250L):

• Install cost: $1,500
• Annual running cost: $950
• Maintenance: $200
• 10-year total: $11,200

The heat pump saves $7,200 over 10 years compared to gas storage and $4,900 compared to electric storage. Factor in that gas prices are rising 4-6% per year and electricity from renewables is stabilising, and the gap widens further in years 5-10.

If you add solar self-consumption to the heat pump scenario (running cost drops to $80/year), the 10-year TCO drops to $3,900, saving over $9,600 compared to gas.