The economics of flexible hot water

How much does hot water really cost?

Hot water needs the same amount of energy either way. What changes the cost is when that energy is used.

12 kWh / day4,380 kWh / yearAll figures ex GST

The same amount of electricity. Very different underlying economics.

Mercury

$1,267

4,380 kWh at Mercury’s 28.92c/kWh
variable energy rate.

Heatr

~$98Projected

4,380 kWh shifted into lower-cost
wholesale periods.

$89.47 actual+$8.26 forecast

Wholesale energy cost against a retail energy rate: it shows the underlying economics, and is not a retail savings forecast. How this is calculated ↓

How this is calculatedThe evidence behind ~$98

Cumulative wholesale energy cost through each year

202420252026 actual2026 forecast
$0$200$400$600JanFebMarAprMayJunJulAugSepOctNovDec2024$5482025$386$89.47 actual at 29 Sep2026 PROJECTED~$98$0$200$400$600JFMAMJJASOND2024 $5482025 $386$89.47 actual at 29 Sep~$98 PROJECTED

The load

12 kWh a day: 4,380 kWh a year.

Each day’s hot-water energy requirement is shifted into the lowest-cost suitable wholesale periods available that day, within the heating capability of the cylinder.

The prices

Electricity Authority final energy prices at the PEN0331 pricing node.

What’s included

Heatr figures are wholesale energy only.

What’s not included

GST, network charges, metering, levies, retailer costs and margins, and fixed charges.

The Mercury comparison uses its 28.92c/kWh ex-GST variable retail energy rate only.

Why timing matters

Electricity is cheap when you can choose when to use it.

Electricity prices vary depending on when energy is consumed. A hot-water cylinder gives us something valuable: storage.

We shift when the water heats — not when you shower.

  1. Lower-cost electricity

    Heating is scheduled for when electricity costs less.

  2. Heat

    The cylinder’s element turns that electricity into heat.

  3. Stored hot water

    The insulated cylinder holds that heat for hours.

  4. Used later

    Showers and taps as usual — nothing changes for the household.

The storage already exists

Don’t use an expensive battery to heat your hot water.

Your hot-water cylinder is already a thermal battery.

Hot-water cylinder cutaway: hot water in red at the top, cold water in blue at the bottom, with a Heatr controller mounted on the side.
Stored heatthe “charge”Heatr controllerdecides when to heat

If the energy is ultimately needed as hot water, it can be stored directly as heat rather than first storing electricity in an expensive electrical battery and later converting it to heat.

That physical thermal storage is already installed in millions of homes.

Heatr makes that storage intelligent.

Heatr understands how much useful energy is stored in the cylinder and controls when it heats, while maintaining the hot water the household needs.

See how Heatr works →
Flexibility for your household

Want cheaper electricity at home? Meet Shifted Energy.

Heatr provides the load-control technology. Shifted Energy is where that flexibility could show up on a household bill.

Explore Shifted Energy Continues to the Shifted Energy website.
Example bill · Concept
shiftedWeek 07

Here’s your week’s power.

$43.32Week ending 15 Feb 2026
Your last 6 weeksavg $43.03/wk
W02W03W04W05W06W07
Your week, by cost161.32 kWh
Heatr Hot WaterIllustrative line item
$10.00
Other electricity
$15.46
Network costs
$12.21
Subtotal · GST
$37.67 · $5.65
Total
$43.32

Illustrative concept showing how intelligently shifted electricity could appear on a household bill.

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info@heatr.ai