Heat pump vs solar hot water — which is worth it in Melbourne?

Both heat pumps and solar hot water systems are dramatically more energy-efficient than standard electric or gas systems — but they work very differently and suit different homes. Here's how they compare for Melbourne conditions.

How they work

A heat pump works like a reverse air conditioner. It extracts heat energy from the surrounding air and uses it to heat water. Because it's moving heat rather than generating it, it uses around 65–75% less electricity than a standard electric element. The unit sits on the ground next to or near your home.

A solar hot water system uses roof-mounted collectors (either flat panels or evacuated tubes) to capture heat from the sun and transfer it to a storage tank. A gas or electric booster kicks in on cloudy days or during high-demand periods. The collectors sit on your roof alongside (or instead of) solar PV panels.

Side-by-side comparison

Factor	Heat pump	Solar hot water
Upfront cost	$2,400–$4,500 installed	$3,300–$6,500 installed
Annual running cost	~$150–$300	~$80–$200
VIC VEU rebate	Yes — up to ~$1,000 off	Partial — STCs apply
Roof space needed	No	Yes — north-facing panels
Works without sun	Yes (needs air, not sun)	Booster required
Works in cold weather	Good (modern models to -10°C)	Reduced efficiency
Maintenance	Very low	Panel cleaning, valve checks
Lifespan	15–20 years	20+ years (panels longer)

Melbourne-specific considerations

Melbourne gets around 2,200 sunshine hours per year — less than Brisbane or Perth, but still enough for solar hot water to perform well for most of the year. The main challenge is winter, when overcast skies mean the booster runs more frequently, increasing running costs during June–August.

Heat pumps perform well in Melbourne year-round. Modern units operate efficiently even when the outside temperature drops to single digits, which covers virtually all Melbourne winter nights. The consistent performance across seasons is a genuine advantage in Melbourne's variable climate.

What if you already have rooftop solar PV panels?

If you already have solar electricity panels generating excess power during the day, a heat pump can be configured to run during peak solar generation hours — effectively running on free electricity. This combination is becoming very popular in Melbourne and can reduce hot water running costs close to zero. A solar hot water system alongside solar PV panels adds complexity and additional roof equipment.

Important: If you're installing new rooftop solar PV panels and also want solar hot water, discuss both systems together with your plumber and solar installer. There may be roof space trade-offs to consider.

Which is better for Melbourne?

Our recommendation

For most Melbourne homes, a heat pump is the better choice — lower upfront cost after rebates, consistent year-round performance, no roof access needed, and it pairs beautifully with existing solar PV panels. Solar hot water makes more sense if you have excellent north-facing roof space, no existing solar PV, and want the absolute lowest long-term running costs and don't mind a higher upfront investment.