{"id":93332,"date":"2025-08-05T08:31:59","date_gmt":"2025-08-04T23:01:59","guid":{"rendered":"https:\/\/www.solarquotes.com.au\/blog\/?p=93332"},"modified":"2025-08-06T09:14:03","modified_gmt":"2025-08-05T23:44:03","slug":"heat-pumps-win-the-hot-water-efficiency-war","status":"publish","type":"post","link":"https:\/\/www.solarquotes.com.au\/blog\/heat-pumps-win-the-hot-water-efficiency-war\/","title":{"rendered":"Heat Pumps Win The Hot Water Efficiency War"},"content":{"rendered":"

\"AWhen it comes to efficiency, hot water heat pumps have long had the definitive edge over alternative technologies anywhere south of Brisbane. Our latest analysis further upgrades this advice: heat pumps today are the most efficient way to heat your hot water, no matter what area of Australia you live.<\/p>\n

The Brisbane line once represented the supposed plan<\/a> Australia had to abandon most of the country during World War Two, but in the energy efficiency world it represents a different line of defense entirely: north of Brisbane being the last area where there was at least some competition to hot water heat pumps.<\/p>\n

Heat pumps are more efficient than conventional resistive electric hot water systems as they move heat rather than creating it, consuming way less energy.<\/p>\n

However, efficiency comparisons with solar thermal hot water systems, which use roof-mounted flat plates or evacuated tubes to heat water directly using the sun, haven’t been quite so straightforward.<\/p>\n

Our advice until now is that heat pumps were definitively the most efficient option south of Brisbane, due to lower ambient temperatures and sun hours. But our revised verdict is that solar thermal doesn’t keep up even in the north, especially if the heat pump is paired with solar panels.<\/p>\n

At First Glance, Solar Thermal Still Has The Edge<\/h2>\n

SolarQuotes\u2019 resident fact-checker Ronald Brakels says that surface-level analysis can give the impression that solar thermal hot water panels still have their noses in front:<\/p>\n

\u201cThese days typical new panel efficiency is around 22%. Full sunlight is close is roughly 1,000W per square metre. So one square metre of 22% efficient solar panels will produce 220W of electric power under 1,000W of full sunlight. If we use the rule of thumb that a typical heat pump hot water system uses 1\/3 as much as electricity as a conventional hot water system, that means it will provide 660W of heat energy to the water, making them 66% efficient,\u201d he says. \u201cSolar thermal hot water panels can transfer up to 80% of the energy in sunlight into heat into water, or 800W, so they beat heat pumps.\u201d<\/p><\/blockquote>\n

A Deeper Dive Reveals Otherwise<\/h2>\n

Ronald warns that this isn\u2019t the complete picture, however:<\/p>\n

\u201cBut this is not a fair comparison! The solar thermal hot water efficiency figure is only for directly converting sunlight energy into water heat energy, while the heat pump figure includes losses such as heat loss from the cylinder overnight, which also apply to solar thermal. When put on an equal footing, the average heat pump comes out ahead.\u201d<\/p><\/blockquote>\n

Another factor puts solar PV paired with heat pumps well in front, Ronald says:<\/p>\n

\u201cBut the real killer for solar thermal hot water efficiency occurs when curtailment is considered. This is energy that isn\u2019t used and which effectively goes to waste. In summer, a solar thermal hot water system can produce far more hot water than a household needs. This means much, or most, of the sunlight energy hitting the thermal collectors goes to waste. This can also happen on sunny days outside of summer, depending on hot water use. But with solar PV and a heat pump, if electricity isn\u2019t required for heating water it can instead power the home, charge a battery, or be exported to the grid for others to use. While there are situations in which PV solar can be curtailed, they occur far less frequently than for solar thermal. Once this is factored in it ruins efficiency comparisons for solar thermal hot water, leaving PV solar + heat pumps the clear efficiency kings.\u201d<\/p><\/blockquote>\n

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Another Brisbane line remains in place however: zones 1 and 2 in the map above get a reduced hot water rebate<\/a>, as hot regions typically have lower hot water use.<\/p><\/div>\n

Does Solar Thermal Hot Water Retain Any Advantages?<\/h2>\n

These days, you\u2019re not likely to save money by installing a solar thermal hot water system as opposed to large PV solar system and using a heat pump hot water system or a conventional electric hot water system on a timer.<\/p>\n

Even if you don\u2019t have solar PV you\u2019re not likely to save money, as an electrically boosted solar thermal hot water system uses roughly the same amount of electricity as heat pump hot water. But there are a few advantages:<\/p>\n