Let’s say you’ve got a nice, big solar system all set up on your roof. While you’ve seen savings, your hot water system continues to guzzle the power you’re generating. If you’re in that situation, your next step might be to upgrade to a heat pump hot water system.

The best models will integrate with your solar system, using a smart controller to maximise your savings. Here, we explain just how that works, and what difference you could expect to see on your hot water bill.

How heat pump hot water systems work – a quick rundown

To understand why you’d want to integrate a heat pump system into your solar system, you’ll first have to understand how they work.

Basically, a heat pump takes heat from the outside air and uses it to heat a tank of water. By contrast, a traditional electric storage system (the most common system in Victoria), uses an electric element to directly heat water.

That’s the basics, but we have a more in-depth explanation available here.

The reason a heat pump can save you money is efficiency. Traditional electric heating is basically 100% efficient, which means 1kW of electricity becomes 1kW of heating power. While we typically think of 100% efficiency as impressive, that’s not the case when it comes to water heating.

A great heat pump can be 500% efficient, turning 1kW of electricity to 5kW of heating power. What would take 5kW with an electric storage system only takes 1kW, which means an 80% reduction in energy costs. That’s impressive, but gets even more impressive with solar.

Why you’d want to integrate solar with a heat pump

The days of high feed-in tariffs are long behind us. While it used to make sense to get a solar system to make money exporting to the grid, this isn’t really possible anymore. Nowadays, the reason to have solar is to spend less. With power prices rising across Australia, that’ll only become more and more true.

Outside of some on legacy plans that still have the high feed-in tariffs of yesterday, most electricity consumers are better off using as much of their solar generation as possible. Power just costs more than the feed-in tariff pays, and that’s not likely to change.

This is where a heat pump hot water system comes in. Some heat pumps feature a smart controller that allows them to integrate with an existing solar system. This allows you to set your heat pump to top up your hot water at times when you’re producing the most solar power, letting you heat the tank for free.

In this way, a heat pump system functions somewhat like a battery – and for much cheaper than an actual battery would cost. Rather than storing your produced power as electricity, ready to be sent around the house as needed, it stores your power as heat energy, reducing the amount you need to use to heat water later in the day. While not as flexible as a real battery, it’s still a way to save money and get the most out of a solar system.

This intelligent control minimises the amount you feed back into the grid, which, in turn, maximises your savings. As you might remember from our article on levelised cost of power, offsetting as much of your energy use as you can is ideal.

Can every heat pump do this?

While every heat pump can help you save (at least compared to traditional systems), they don’t all do it with the same level of efficiency or intelligence.

Take the Reclaim Energy CO2 Heat Pump. The included smart controller gives you five options, including the choice to run 24/7 or during off-peak periods for those who have off-peak pricing in their electricity plan. But the important one here is an option for homes with solar systems. It runs during peak solar production, giving you the benefits we discussed above.

The Sanden Eco Plus has a timer that works much the same. However, if you use all your hot water outside of the set period, the system won’t override it to produce more. The Reclaim will. But these are two premium quality models, and not all heat pumps are created equal.

Some systems without a controller have the option to install one, but others don’t. Even then, less efficient models will struggle When you’re shopping for a heat pump and have solar panels, this is something to keep in mind. Intelligent integration is a great way to save money and maximise the value of your solar investment.

Maximum value from maximum efficiency

Something else to keep in mind is that it’s not all about having a controller. The more efficient your heat pump is, the more you’ll save.

If a decent quality system takes three hours to refill your tank with solar system, you’ll spend three hours drawing from your production. If a premium quality heat pump does it in half the time, then that extra time and energy is freed up for your solar to power the rest of your house, or potentially be fed back into the grid.

We’ve discussed how offsetting your own usage is better than chasing a tariff, but once you’ve offset everything you can, getting a small tariff back is better than none at all. The more efficient your heat pump is, the better your chances of being able to fully power your home and then earn a feed-in tariff.


If you’ve got a solar system, there’s a good chance a heat pump should be your next investment. One that can efficiently turn your generated power into hot water will free up your power for other appliances and, essentially, act as a thermal battery. The more efficient, the more power you save – and therefore the more money you save.

If you want to know the basics about heat pumps, we’ve got plenty of articles you can learn from.

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