Solar Diverter for Hot Water in Australia: Worth It, or Is a Timer Enough? (2026)

A solar diverter for hot water is worth it in Australia only in a narrow set of homes: those with a big solar system, a low feed-in tariff and an electric storage tank with years of life left. For most households, a cheap timer that runs the tank in the middle of the day gets you most of the benefit for a fraction of the price. If the tank is near the end of its life, a heat pump usually beats both.

The question comes up constantly among solar owners because feed-in tariffs have collapsed. IPART’s benchmark for NSW solar exports fell to 3.4 to 6.5 cents per kWh for 2026–27, down from 4.8 to 7.3 cents the year before. Victoria no longer sets a minimum feed-in tariff at all. Exporting solar is now worth very little, so using it yourself matters more. Hot water is the obvious place to put it: water heating makes up 15% to 30% of household energy use, according to energy.gov.au.

What a solar diverter for hot water actually does

A solar diverter is a controller that sends surplus solar power into your electric hot water tank instead of exporting it to the grid. It uses a current transformer (CT) clamp, a sensor clipped around the main grid cable, to measure how much power your home is exporting. When it sees surplus, it feeds that amount to the tank’s heating element, adjusting second by second.

That proportional control is the key difference from a timer. Say your panels have 1.5 kW spare. A diverter sends 1.5 kW to the element and exports nothing. A timer switches the element on at full power, typically 3.6 kW on a standard tank, and your home imports the 2.1 kW gap from the grid.

Diverters only work with resistive elements. They do not work with heat pumps, gas or solar thermal systems. Most let you set a timed boost from the grid so the tank still reaches temperature on cloudy days.

Solar diverter hot water prices in Australia

Most diverters cost about $450 to $1,000 for the unit, plus installation by a licensed electrician. As of September 2026, the main products sold in Australia list at these prices on their manufacturers’ Australian sites:

Product	Type	Supply price (Sept 2026)	Made in
myenergi eddi	Proportional diverter	$995	UK brand
Paladin Solar Power Diverter	Proportional diverter	$990	New Zealand
Catch Control (formerly Catch Solar Relay)	Solar-aware relay and timer	$447	Australia

Installation typically adds $250 to $350, which puts a proportional diverter at roughly $1,000 to $1,300 fitted. Catch Power also makes proportional diverters, the Catch Green and Catch Blue, with three-phase versions costing more.

The Catch Control is a different kind of device. It switches a load on and off based on solar production, time, or both, rather than feeding it a variable amount. That makes it a smarter timer rather than a true diverter, and it is the only product here made in Australia. Because it simply switches power on and off, it can also control inductive loads such as a heat pump, which a proportional diverter cannot run.

The payback maths: diverter vs timer

A diverter saves the gap between what you pay for hot water now and what you would have earned exporting that solar. On most bills that gap is only about 10 cents per kWh.

Here is a worked example for a NSW household with a 315-litre electric tank on controlled load. The assumptions are illustrative, so swap in the numbers from your own bill:

Item	Assumption
Hot water energy use	8 kWh a day (2,920 kWh a year)
Controlled load rate	15c per kWh
Solar feed-in tariff	5c per kWh
Share of hot water a diverter can cover	70% (less in winter)

Each diverted kWh saves 15 cents but gives up 5 cents of export income, a net 10 cents. Covering 70% of 2,920 kWh saves about $204 a year. A diverter at $1,000 to $1,300 installed pays back in five to six and a half years. Push the feed-in tariff down to 3 cents and the controlled load rate up to 17 cents, and the saving rises to about $290 a year, a payback of around four years.

That is a modest return. Solar owners who run the numbers on their own bills tend to land in the same place, often finding annual savings of $150 to $300. The reason is that controlled load is already cheap. You are displacing 15-cent electricity, not 30-cent electricity.

A timer changes the maths. Instead of keeping the tank on controlled load, an electrician moves it to your main circuit and fits a timer set to run from about 10 am to 3 pm. On a sunny day your panels cover most of the element’s draw. On a cloudy day you pay the full general rate for part of it, which can be double the controlled load price. The upfront cost is usually a few hundred dollars for the electrician and timer. For a household that is home a lot and has 6.6 kW or more of solar, a timer captures much of what a diverter would, at a quarter of the cost.

The trade-off is winter. A diverter squeezes every spare watt into the tank on a weak winter day. A timer drawing 3.6 kW against 2 kW of solar imports the rest from the grid at full price. If you live somewhere with long, grey winters, the diverter’s advantage grows.

How the Solar Sharer Offer changes the answer

If you are in NSW, South East Queensland or South Australia and switch to a Solar Sharer Offer plan, a timer can beat a diverter outright. The plan gives you free electricity for three hours each day: 11 am to 2 pm in NSW and South East Queensland, and 12 pm to 3 pm in South Australia. The first 24 kWh is free, according to Energy Made Easy.

A 3.6 kW element running for the full three hours uses about 10.8 kWh, which covers most households’ daily hot water. Set a timer to the free window and the tank heats for nothing, rain or shine. A diverter’s only remaining edge is the small amount of export income it avoids giving up.

Two catches apply. First, controlled load circuits do not get the free window, so the tank must be moved onto your main circuit. Some distributors charge to remove the old load-control device, so get a quote first. Second, Solar Sharer plans carry higher rates outside the window, and they do not suit every household. Check the whole plan before moving your hot water around it.

Victoria launches its own version, the Victorian Midday Power Saver, on 1 October 2026 with a free window from 11 am to 2 pm. The same timer logic applies there.

Why a heat pump often makes both redundant

A heat pump water heater uses about 30% of the energy of a conventional electric storage system, according to energy.gov.au. That changes everything about solar sizing. A tank that needed 8 kWh a day as a resistive system needs roughly 2.4 kWh as a heat pump. A modest solar system covers that easily on most days, with a simple built-in timer and no diverter at all.

Heat pumps also earn rebates that diverters do not. Air-source heat pumps under 425 litres on the Clean Energy Regulator’s register qualify for small-scale technology certificates (STCs), a federal discount applied at the point of sale. In Victoria, the Solar Homes hot water rebate adds up to $1,000, or up to $1,400 for a locally made product, for owner-occupiers with a combined household income under $150,000. NSW has its own hot water upgrade incentives. We found no federal or state rebate for solar diverters.

Option	Upfront cost (Sept 2026)	Rebates	Best for
Timer on main circuit	A few hundred dollars	None	Solar homes with a healthy electric tank, or anyone on a Solar Sharer plan
Proportional solar diverter	About $1,000 to $1,300 installed	None found	Big solar systems, low feed-in tariffs, cloudy winters, tank with years of life left
Heat pump	$2,500 to $5,000 installed after STCs for most homes	STCs, plus state rebates in some states	Tanks near the end of their life, or anyone replacing gas

The rule of thumb is simple. If your electric tank is less than about five years old, a timer or diverter makes sense. If it is 10 years old or leaking, put the diverter money towards a heat pump instead. Our heat pump hot water cost guide breaks down installed prices by brand, and the heat pump payback calculator runs the numbers for your household.

Traps to check before you buy a diverter

Most diverter disappointment comes from a few predictable problems.

• Legionella and the 60°C rule. Storage tanks must heat water to at least 60°C to control Legionella bacteria. Queensland Health states tanks are required by law to store water at 60°C or more. Make sure your diverter’s boost timer guarantees that temperature on days with little sun.
• Controlled load wiring. Diverters normally run on a circuit billed at your general rate, not controlled load. Moving the tank off controlled load adds electrician time and, on some networks, a fee to remove the load-control device.
• Competing loads. If you also have a solar-aware EV charger or a battery, decide which gets surplus solar first. Two devices chasing the same export reading can fight each other. Most households put the car or battery first and let the tank take what is left.
• Three-phase homes. A single-phase element on a three-phase home complicates things, because the diverter needs to read the net export across all phases. Ask the installer how the CT clamps will be placed.
• Your network’s daytime controlled load. Some networks now switch controlled load on in the middle of the day. Ausgrid moved its Controlled Load 1 switching times in July 2024 to use daytime solar, and SA Power Networks runs a midday “solar sponge” window. That makes cheap daytime heating possible without buying anything, although controlled load is metered separately and your own panels generally do not offset it.

For most solar homes with an electric tank, the practical order is: check your network’s controlled load times, try a timer, and only buy a diverter if your feed-in tariff is near zero and winters are long. Browse efficient replacements on the heat pumps hub when the tank finally needs replacing.