30/10/2026
Heat pump + solar: the same hot water for about 3c instead of 29c.
Here's the arithmetic that still stops people. An old resistive element is a one-for-one deal — one unit of electricity in, one unit of heat out — and on tariff 31 that's 28-30c a unit off your bill. A heat pump doesn't make heat, it moves it, so it typically delivers around three units of heat for every unit of electricity. Run it at midday on your own roof rather than exporting that power at 9.276c, and the true cost of a unit of heat lands near 3c.
Roughly a tenth. Same shower.
The catch is timing, and it's where we see the most waste. A lot of the hot water timers we come across are still set to fire at 2am, on the old off-peak habit. On a flat tariff 31 that habit now costs you: the cheapest power a flat-tariff household gets is what's already coming off its own roof between about 10 and 3, and a hot water tank is the easiest battery in the house — no paperwork, no inverter, just a clock change.
What time is your hot water set to heat, and do you know where that timer actually lives?