Heat Pump Hot Water — A Buyer's Guide
Heat pumps use one unit of electricity to make three or four units of heat. Here's how to choose one and how it interacts with your solar.
Hot water is typically 20-30% of a household electricity bill. A heat pump hot water unit uses 60-75% less electricity than a standard resistive electric element to heat the same volume of water — and it's the perfect dispatchable load for soaking up daytime solar.
How they work
A heat pump hot water system is a small fridge running in reverse. It pulls heat from the ambient air and pumps it into the water tank. Coefficient of Performance (COP) is the key metric — a COP of 4 means you get 4 kWh of heating for every 1 kWh of electricity. Most modern units sit between COP 3.5 and 5.0 in mild climates.
Performance drops in very cold air, which matters in the Limestone Coast in July. Quality units (Sanden, Reclaim, iStore, Stiebel Eltron) maintain a strong COP down to ~5°C ambient.
Pair it with solar
Every heat pump worth buying has a programmable timer. Set the unit to heat only during your solar export window (e.g. 10am-3pm). That converts what would otherwise be 4-5c export to 40c worth of avoided grid imports overnight. On a typical SA household this single change is worth $400-$700/year.
Smart controllers (Catch Power Green Catch, Paladin) can dynamically modulate the heater to track solar surplus in real time — useful on cloudy variable days.
Sizing & install notes
270-315L is the standard family size. Smaller (160-200L) for couples and units. Larger (400L+) for big families and electric-only homes.
Heat pumps need airflow and they make some noise — typically 35-50 dB at 1m. Avoid installing under a bedroom window. Outdoor split units (Sanden, Reclaim) are quieter than integrated units.
Most STC-eligible heat pumps qualify for a significant federal rebate (typically $800-$1,400). Some SA retailers and energy upgrades programs add a separate incentive on top.
Key takeaways
- COP 3.5-5.0 — heat pumps use a quarter of the electricity of a resistive element.
- Timer them onto your solar window for the best return.
- Sanden, Reclaim, iStore and Stiebel Eltron are the units we recommend.
Sources & further reading
This article is general information only. Figures change with policy, tariffs and product pricing — for a current quote tailored to your home, start an assessment or contact our team.