Solar hot water diverters in Perth: redirect excess solar instead of exporting at 2c

A solar diverter redirects the excess solar power your panels are generating into your electric hot water system instead of letting it export to the grid. In Perth, that swap is worth chasing: under the Distributed Energy Buyback Scheme (DEBS), exporting during the off-peak window (9am to 3pm) earns just 2c/kWh, while self-consuming that same power on the A1 tariff saves 33.26c/kWh. That's a 31.26c/kWh gap, and for most Perth households the off-peak export window covers most of the day's solar output, the hours when panels are producing the most. A lot of "free" energy has nowhere better to go than 2c a unit unless something intercepts it first.

A diverter closes that gap. It watches your inverter output and your household's live consumption, then sends the difference (the amount that would otherwise export) to your hot water element instead. The tank becomes a thermal battery: it stores solar energy as hot water rather than sending it to the grid for next to nothing.

How does a solar diverter work?

Two numbers drive the diversion: how much your inverter is generating, and how much your house is drawing right now. A diverter sitting at your switchboard reads both continuously, and whatever's left over (the surplus that would otherwise flow out to the grid) gets sent to the hot water element at a controlled rate.

The key is that it matches supply, not just switches the element on. A standard hot water element draws 2.4 to 3.6kW flat out. Rather than flicking that on and pulling grid power to make up the shortfall, the diverter uses power electronics to throttle the element down to exactly the surplus available. If you've got 1.2kW of excess solar, the diverter feeds the element 1.2kW, not 3.6kW.

That means the element only ever runs on solar you'd otherwise be exporting. No grid electricity gets imported to top it up. The trade-off is time, not power: the element runs longer at a lower draw to get the same heating effect.

Which solar diverters are actually available in Australia?

1. Catch Power (Green). Australian-designed and manufactured, and the most common diverter brand in Perth. It's a single-element residential product. Installed pricing depends mostly on your supply type: on a single-phase home it typically runs $450 to $650, while a three-phase home needs current monitoring on each phase and more switchboard work, which usually puts it closer to $850 to $900. Most Perth homes are single-phase, but check your switchboard before you budget, and get a firm quote either way. It can be monitored through an app, and local support is good. (The original Blue model has been discontinued, though existing units are still supported.) For a broader look at how the numbers add up across a typical Perth household, see our companion guide to solar diverters for hot water.
2. iBoost (Marlec). A UK-designed diverter with no current Australian distributor, so it isn't a practical option for a Perth installation right now. If you've seen it recommended elsewhere, treat that as outdated: Catch Power and Eddi are the two options actually sold here.
3. Eddi (myenergi). UK-designed, with growing Australian availability. It's part of the myenergi ecosystem alongside the Zappi EV charger, and it's more capable than a basic diverter: it can manage multiple loads (hot water, EV, pool pump) with priority ordering between them. Pricing moves around more than Catch Power's, so treat $600 to $900 installed as a rough guide and confirm the current number with a retailer.
4. SolarEdge Home Battery / Home Hub. If you already have a SolarEdge inverter, you can configure self-consumption routing directly through its platform, achieving a similar effect without a separate diverter device. Only relevant if SolarEdge is your inverter brand.

How much does a diverter cost compared to the alternatives?

A diverter isn't a replacement for a heat pump or a battery. It's a targeted, low-cost fix for one specific problem: exporting at 2c when you could be saving 33.26c on hot water.

Here's how the economics play out for a typical Perth home:

1. A home exporting 5kWh/day of surplus solar earns $0.10/day at the 2c off-peak rate.
2. If a diverter redirects 3kWh of that surplus to hot water instead, it avoids 3kWh of grid electricity at 33.26c/kWh while giving up that same 3kWh of 2c export, a net 31.26c/kWh saving, or roughly $0.94/day.
3. Over a year, that's about $340 on the A1 tariff.
4. Against a single-phase installed cost of $450 to $650, that's a payback of roughly 1.3 to 1.9 years. On a three-phase install at $850 to $900, the same $340 a year takes about two and a half years to pay the unit off.

Against a heat pump: a heat pump hot water system uses roughly three to five times less electricity for the same heating output, depending on the model and the air and water temperature on the day, with around four times typical in Perth conditions. If your existing resistive system is on its way out anyway, a heat pump is the better long-term move: it improves efficiency no matter where the electricity comes from, not just when you have solar surplus to spare. A diverter doesn't change that efficiency, it only changes the source. For a closer look at that trade-off, see our guide to choosing between a solar diverter and heat pump hot water.

Against a battery: a 10kWh battery stores surplus solar for every load in the evening, hot water included, so its value is broader. But the upfront cost is an order of magnitude higher, and payback stretches out accordingly. A diverter makes sense as a standalone low-cost option, or as a companion to a battery if you generate more surplus than the battery can absorb on a sunny day. If a battery is the bigger decision you're weighing, our guide to battery ROI in Perth breaks down that economics separately.

When does a solar diverter make sense?

A solar diverter is a good fit when:

• You've got an existing electric (resistive) hot water system that's in good condition and not worth replacing yet.
• Your solar system is 6.6kW or larger, enough for reliable midday surplus.
• You're not planning to add a battery immediately, so the diverter captures the surplus in the meantime.
• You're on the A1 tariff rather than Midday Saver. Under Midday Saver, the super off-peak rate is 8.85c, so the self-consumption saving drops to 6.85c against the same 2c export, still positive, just smaller.

A diverter is less compelling when:

• You already have a heat pump hot water system. Heat pumps are already efficient, so a diverter adds little on top.
• You're on Midday Saver with heavy evening usage. A battery covering the 55.33c/kWh peak window delivers far more value per dollar than a diverter would.
• Your hot water system is due for replacement anyway, in which case a heat pump is the better place to put that money.

If a diverter is more than you want to spend right now, there's a free option worth trying first: shifting your hot water timer to run during solar hours instead of overnight. It's less precise than a diverter, but it captures some of the same value at zero cost.

What do you need to install one?

• Any standard single-phase electric hot water system with a resistive element. The element itself needs no modification.
• A compatible solar inverter. Most diverters work with any inverter brand via clamp-meter sensing, though some offer direct CT integration.
• A licensed electrician to install it, typically a 2 to 3 hour job.
• Some diverters need a separate current transformer (CT) clamp fitted at the grid connection point.

If your hot water system currently runs on a controlled-load (off-peak) tariff circuit, a common setup in older Perth homes, talk to your installer about how the diverter interacts with that existing meter configuration before you commit.

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Product pricing is indicative mid-2026 and varies by installer. DEBS rates and A1 tariff effective 1 July 2026. Savings calculations are illustrative: actual savings depend on your solar generation pattern, hot water usage, and tariff.