Heat pump vs solar hot water: which suits your home?

Both systems cut the cost of heating water, but they do it differently. A heat pump uses electricity to pull warmth out of the air. A solar system heats water directly with sunlight on the roof. Which works better for you comes down to your roof, your climate, and whether you already have solar panels.

Heat pump vs solar hot water at a glance

How a heat pump works

A heat pump uses a refrigerant cycle to pull heat from the surrounding air and move it into the water tank. It runs on electricity, but uses far less than an old electric storage system that heats water with an element, because most of the heat comes from the air.

There are two layouts. In an integrated unit, the fan and compressor sit on top of or beside the tank. In a split system, the heat pump is a separate outdoor unit plumbed to the tank, so the tank can go inside. Integrated units are compact and simpler to install, but heavy.

Noise and placement

Solar Victoria’s heat pump planning guide reports noise levels comparable to modern refrigerators. Because the unit can start at any hour, put it outside a kitchen, laundry or bathroom rather than a bedroom, or use a timer so it only runs during the day.

In cold climates

Performance depends on the model’s operating temperature range, which is listed in its brochure or datasheet. Some units struggle near freezing and fall back on an electric element, which costs more to run. If your area gets regular frosts, choose a model that keeps working without a resistive booster.

How solar hot water works

Collectors on the roof absorb sunlight and heat water, which is stored in an insulated tank. On a close-coupled system the tank sits on the roof above the collectors. On a split or pumped system the tank stays on the ground and a small pump moves water to the roof and back.

Solar collectors can’t gather enough energy on cloudy days or through winter, so every system has a gas or electric booster that switches on automatically. In warmer months it may run on sunlight alone.

What your roof needs

Collectors perform best facing north. East- or west-facing roofs can work with a larger collector, but a roof shaded by trees or a neighbouring building is a reason to choose a heat pump. In frost-prone areas, choose a closed-loop system, which protects the collectors from freezing.

Which one suits your home?

• You have rooftop solar panels: a heat pump on a midday timer or solar diverter can run on your own power for much of the year.
• Your roof is shaded: a heat pump, because it doesn’t need sun on the roof.
• You have a large, unshaded north-facing roof and no solar panels: solar hot water is a strong option, with a booster for winter.
• You get regular frosts: a heat pump rated to keep working near freezing without a resistive booster, or a closed-loop solar system.
• The only spot is outside a bedroom: a split heat pump with the tank inside, or a timer that keeps it running during the day.

Solar Victoria’s guide to choosing between the two notes that a heat pump timed for midday could run entirely on rooftop solar for much or all of the year, depending on your household’s use and the size of your solar system.

Costs and rebates

Prices depend on tank size, brand, and how much plumbing and electrical work your home needs, so get quotes for the system you’d actually install. Two kinds of incentive bring the price down:

• STCs, in every state. Eligible heat pumps and solar water heaters create small-scale technology certificates. Retailers usually take their value off the price.
• State programs. Some states add their own rebates or discounts on top.

In Victoria

The Solar Victoria hot water rebate covers 50% of the system’s price after other discounts, up to $1,000, or up to $1,400 for an eligible locally made system. To qualify:

• you own and live in the home, and it’s valued under $3 million
• the combined taxable income of all owners is under $150,000 a year
• the hot water system you’re replacing is at least 3 years old
• the address hasn’t already had a Solar Homes hot water or battery rebate
• you buy through a Solar Victoria authorised retailer.

If the retailer is also an accredited Victorian Energy Upgrades (VEU) provider, you can combine the rebate with a VEU discount. Solar Victoria says combined upfront savings can reach $2,030 for an eligible locally made system, or $1,630 for other eligible systems.

Outside Victoria, check your state or territory energy department for current hot water programs.

Before you replace anything

A new system isn’t the only way to cut hot water costs. Solar Victoria suggests cheaper fixes first: a low-flow showerhead, aerating taps, insulation on hot water pipes, and a tank blanket. Keep stored water at 60°C or more to prevent Legionella.

If you are replacing the system, size it to your household. Solar Victoria’s guide to tank sizes walks through it.

When you’re ready to compare options, you can see hot water retailers that service your postcode, including Solar Victoria authorised retailers if you’re in Victoria.

This guide is general information, not financial or legal advice. Rules, rebates and prices change, so check the linked sources before you decide. Facts checked 18 October 2026.