Save on Power Bills: Hot Water Diverter for 5 kW+ Australian Homes
Energy costs
If you already have solar panels and a working electric hot water tank, a hot water diverter solar setup is usually one of the fastest, lowest-risk ways to cut your power bill. It suits homes with 5 kW or more of solar capacity and regular daytime export, and it beats a timer on accuracy every time. The main trade-off is upfront cost against a quicker payback, and it’s worth weighing against a battery or heat pump before you commit.
TL;DR:
- Diverters work best with systems of 5 kW or more and households that regularly use hot water during the day, maximizing surplus solar utilization.
- Costs range from budget models to premium smart units, with payback times heavily influenced by hot water consumption, feed-in tariffs, and tank insulation quality.
- Proper installation involves a licensed electrician fitting a CT clamp at the switchboard, wiring the diverter near the tank, and verifying real-time export diversion before completion.
- Diverters are generally more affordable and easier to install than heat pumps or batteries, making them a practical first step for solar owners seeking quick savings.
- Check phase compatibility, element rating, local support, warranty terms, and live export data during purchase to avoid common pitfalls and ensure system effectiveness.
Table of Contents
- What is a hot water diverter and how does it compare to other models?
- How does a solar diverter work?
- Who actually benefits from installing one?
- What does installation actually involve?
- What does a diverter cost, and when does it pay for itself?
- How do diverters compare with heat pumps and batteries?
- What should you check before buying a diverter?
- Why Solar X Energy takes a measured view on diverters
- Sources
- FAQ
What is a hot water diverter and how does it compare to other models?
A solar hot water diverter redirects surplus electricity from your panels, power that would otherwise flow back to the grid for a modest feed-in credit, into your electric hot water element instead. That’s the whole idea. Rather than paying for grid electricity to heat water later, you use free solar power to do the job the moment it’s generated.
Diverters generally fall into three practical categories:
- Basic proportional diverters vary the power sent to the element in real time, matching it closely to available surplus.
- Threshold or dual-output diverters switch power on and off in steps, or split output between two heating elements or two loads.
- Internet-connected smart diverters add app monitoring, data logging, and sometimes weather-aware boost scheduling.
Here’s how the main models sold in Australia stack up:
- Catch Power Green/Blue: Popular Australian-made units, single-phase and three-phase versions available, with the Blue adding app monitoring and load control.
- SunMate: A budget-friendly proportional diverter, single-phase focused, straightforward install with fewer smart features.
- Powerdiverter: Mid-range proportional control with reasonably simple wiring, aimed at retrofit jobs.
- Fronius Ohmpilot: A German-engineered unit that pairs neatly with Fronius inverters and offers precise, accurate load control many installers rate highly for reliability.
- myenergi Eddi: Supports two heating loads and integrates with the wider myenergi ecosystem, useful if you’re already running a myenergi charger or battery.
- Paladin-2: An Australian-designed diverter with a strong track record for tank hygiene management and boost scheduling.
For a full model-by-model rundown with current specs and pricing, SolarQuotes maintains a detailed comparison table that’s worth checking before you commit to a brand.
How does a solar diverter work?
A CT clamp (current transformer) clips around a cable at your switchboard and constantly measures how much power your home is exporting to the grid. The diverter unit reads that signal and does the maths in real time.
- The CT clamp detects surplus export, often within a second or two of it happening.
- The diverter’s controller calculates how much of that surplus it can safely redirect.
- It sends a proportional signal, similar to a dimmer switch, to the immersion element so the exact surplus gets used, no more and no less.
This is the real difference between a diverter and a timer. A timer just switches the element on at a set time and hopes there’s sun. Installer blogs regularly point out that cheap timers give a false sense of savings because they don’t track actual generation, so an overcast morning means you’re heating water with grid power and telling yourself it’s free.
Most diverters also include a grid boost function, which tops up the tank from the grid on a schedule (often overnight) to guarantee hot water and keep the tank hot enough to avoid bacterial growth. Smart units can time that boost to off-peak tariff windows or even factor in weather forecasts to minimise what you pay for it.
Pro Tip: Ask your installer whether the grid boost runs on a fixed schedule or is smart-adjustable. A fixed boost every night regardless of tank temperature can quietly undo a chunk of your solar savings.
Who actually benefits from installing one?
Diverters work best in a fairly specific set of circumstances, and it pays to check where you sit before spending the money.
- System size: 5 kW or more of solar is the rough threshold most installers recommend, since smaller systems rarely produce enough consistent daytime surplus to make a real dent in hot water costs.
- Household size and habits: A family showering morning and night draws down the tank daily, giving the diverter regular work to do; a household that’s out all day and showers once in the evening gets less benefit.
- Roof orientation: North-facing or west-leaning arrays that generate strong midday and afternoon output line up well with typical tank reheating needs.
- Tank condition: The tank has to be a working electric storage unit with a serviceable element. A dying tank is a signal to consider replacing it with a heat pump instead of bolting a diverter onto a system on its last legs.
If you’re leaning toward storing surplus solar rather than converting it to heat, it’s worth reading about solar battery options before deciding between the two.
What does installation actually involve?
A licensed electrician handles the whole job, and for most single-phase homes it’s a same-day install.
- The CT clamp gets fitted at the switchboard, either hard-wired or, on newer models, as a wireless sensor that talks to the diverter unit.
- The diverter unit itself mounts near the switchboard or next to the hot water tank, wherever cable runs are shortest.
- Wiring runs from the diverter to the tank’s immersion element, replacing or supplementing the existing timer circuit.
- On three-phase properties, the job gets more involved. Three-phase diverters cost more and need more complex wiring because the unit has to balance or monitor load across all three phases rather than one.
Expect a compliance certificate for the electrical work, an RCD safety check, and a test of the diverter actually diverting (not just wired in but confirmed to be pulling surplus correctly) before the electrician packs up. Most single-phase installations take two to four hours; three-phase jobs can run longer depending on switchboard access.
Pro Tip: If you’re on three-phase power, check with your solar installer or read up on single-phase versus three-phase differences before getting quotes. It changes which diverter models are even compatible with your property.
What does a diverter cost, and when does it pay for itself?
Installed costs for hot water diverters generally range from budget proportional units to premium smart models with monitoring, and Choice’s buying guide notes diverters sit at the lower end of the cost spectrum compared with heat pumps or batteries, which is part of why they remain a popular first step for solar owners.
The strongest independent evidence on actual savings comes from a UNSW-led study that compared diverters against timers and an intelligent water-heating control system. The diverter used a greater amount of daily excess solar for water heating compared to the timer and an intelligent controller. Diverters delivered the highest average savings of the three, though they carried the highest upfront cost.
Payback speed depends heavily on your circumstances. A household with a low feed-in tariff and high hot water use will typically see a diverter pay for itself faster than one with a generous feed-in rate, since the diverter is effectively replacing a low-value export credit with a full retail-rate saving. Element size and tank insulation also shift the numbers. If you want to model your own scenario before committing, tools for predicting self-consumption savings can give you a more personalised estimate than a generic rule of thumb.
How do diverters compare with heat pumps and batteries?
Each option solves a slightly different problem, and none of them are strictly better in every case.
- Diverters cost less upfront, install quickly, run silently, and have essentially no moving parts to service or replace, since they’re solid-state controllers rather than mechanical systems.
- Heat pumps extract heat from the air rather than generating it directly, so they’re more efficient overall and often qualify for government rebates, but they cost more upfront and involve a compressor that needs periodic servicing.
- Batteries store surplus solar for any use in the home, not just hot water, giving them far broader value, though they cost significantly more than a diverter for the equivalent capacity.
A common and sensible sequence is to fit a diverter now while your existing tank is still working, then add a battery later once budget allows or once your tank eventually needs replacing. That way you’re not paying for storage capacity you don’t yet need, and you’re not leaving free solar hot water on the table in the meantime.
What should you check before buying a diverter?
Run through this before signing anything:
- Confirm phase compatibility. Single-phase and three-phase homes need different diverter models, and getting this wrong means a wasted quote or a mid-install surprise.
- Check the element rating. Your installer should confirm the immersion element’s wattage matches what the diverter is rated to control.
- Ask about local stock and support. A diverter that needs a warranty part shipped from overseas with no local distributor is a headache waiting to happen.
- Get the warranty terms in writing. Ask specifically who handles a warranty claim, the installer or the manufacturer, and how long it typically takes.
- Ask to see export data or a live test. A competent installer can show the CT clamp registering export and the element responding, not just tell you it works.
Watch for a few red flags too: quotes promising unrealistic savings percentages, no compliance certificate offered, no local installer support after the sale, or vague answers about how the grid boost strategy actually runs.
Pro Tip: Get the installer to show you the diverter’s live monitoring screen or app during the install, not just after. Watching the export number drop to near zero as the element kicks in is the simplest proof the system is actually working.
Why Solar X Energy takes a measured view on diverters
Plenty of installers push whatever product they stock hardest. Solar X Energy’s approach with Illawarra homeowners is more of a flowchart than a sales pitch: check your actual export pattern and tank condition first, fit a diverter if the numbers stack up, and only look at a heat pump or battery when you’re replacing the tank anyway or building a longer-term energy strategy.
That order matters because it avoids the common mistake of over-engineering a simple problem. A diverter solves “I have surplus solar and a working tank” cheaply and quickly. Batteries and heat pumps solve bigger, more expensive problems, and they deserve their own separate decision, not a bundled upsell. If you want an honest read on where your system sits, Solar X Energy’s team can assess your solar panel setup and tell you plainly whether a diverter, a battery, or neither makes sense for your home right now.
— Matthew
Sources
- Hot Water PV Diverter Comparison Table
- Solar hot water: How to buy the best system for your home – Choice
- myenergi Eddi product page (AU) – myenergi
FAQ
Are solar hot water diverters worth it?
For most homes with 5 kW or more of solar and a working electric tank, yes. The UNSW study found diverters delivered higher average savings than timers, though they cost more upfront.
What is a solar to hot water diverter?
It’s a device that redirects surplus solar electricity, power your panels generate beyond what your home is using, into your electric hot water element instead of exporting it to the grid.
Can I connect my solar panels to my hot water system in Australia?
Yes, provided you have a working electric storage tank with an immersion element. A licensed electrician fits a CT clamp and diverter unit, a straightforward retrofit on most single-phase homes.
What does a solar diverter do?
It measures surplus solar export in real time and proportionally directs that power to your hot water element, so you use free solar energy for heating instead of selling it back to the grid at a low feed-in rate.
