If you have solar panels, the middle of the day is when your home makes the most electricity, and often when it uses the least. Most of that power goes back to the grid for a small feed-in credit. Solar soaking means using it to heat your hot water instead. A heat pump is one of the best ways to do it.
What is solar soaking?
Solar soaking is running your hot water system during the hours your solar panels produce the most power, so the tank heats on your own solar rather than on electricity from the grid. The hot water tank then acts like a battery: the energy goes in during the day, and you use it as hot water in the evening and the next morning.
Why a heat pump suits solar soaking
A heat pump heats water by moving heat from the air into the tank, so it uses much less electricity than an element heating the water directly. That matters for solar soaking in two ways.
First, it draws less power while it runs, so a typical home solar system can cover more of it without topping up from the grid. Second, it needs less energy overall to heat a full tank, so a few good hours of sunshine go further.
Step 1: check how your hot water is wired
Many Victorian homes have their hot water on a controlled-load circuit, sometimes called off-peak hot water. On controlled load, your electricity distributor decides when the circuit is switched on, and for many homes that has meant overnight.
If your hot water is on controlled load, you may not be able to choose when it heats. Moving it to solar hours can mean changing the wiring at the switchboard and changing your electricity plan. This is a job for a licensed electrician, and worth talking through with your retailer first.
Step 2: set the heating times
A timer is the simple option. Many heat pumps have a built-in timer that lets you set the hours the system is allowed to heat. Where the unit does not have one, an electrician can fit a timer at the switchboard. Set the heating window to the middle of the day, when your panels are producing the most.
What about a solar diverter? Solar diverters are made for tanks with an electric element. They send surplus solar into the element, often at reduced power, as it becomes available. A heat pump works differently, so for most heat pumps a timer is the better fit. Some newer heat pumps and inverters can switch the heat pump on when there is surplus solar; we can tell you whether your equipment can.
Victoria’s Midday Power Saver
Since 1 October 2026, the Victorian Midday Power Saver has given households that sign up, and have a smart meter, free electricity from 11am to 2pm, up to 24 kWh a day. Other rates on that offer can be higher. That window is a good fit for a heat pump on a timer, even on days when your panels are not producing much.
Two things to check before you switch:
- The free period covers your general supply only. If your hot water is on controlled load, it keeps its own tariff, and moving it onto general supply is switchboard work for a licensed electrician.
- Rates outside the free window are different from your current plan. Compare the whole tariff, not just the midday hours.
Winter and cloudy days
Your solar panels produce less in winter and on cloudy days, and your household probably uses more hot water. A heat pump will still heat the tank when the timer allows it; on a dull day more of that power comes from the grid. A longer heating window in the cooler months, or a short top-up window later in the day, helps keep the tank hot without going back to heating overnight.
Solar soaking with a home battery
If you also have a battery, the hot water tank and the battery work together. The heat pump can take the midday solar first, and the battery stores what is left for the evening. Getting the timing right means your solar does as much work as possible before anything goes back to the grid.
How Helcro Electrical can help
We install solar panels, batteries and heat pump hot water systems from iStore, Sanden and Haier, so we can look at the whole setup: your solar system, your switchboard and how your hot water is wired. Our heat pump hot water installations come with a 5-year workmanship warranty, and our solar and battery installations with a 10-year workmanship warranty.
Helcro Electrical is an authorised retailer on Solar Victoria’s list, a VEU Accredited Provider (A003039) and a New Energy Tech Consumer Code (NETCC) Approved Seller for solar and batteries. Read our guide to heat pump vs electric hot water, or see our heat pump and solar pages.
If you are in Melbourne’s South East and want your hot water running on your solar, call us on 1300 201 358 for a written quote.
