Inverters
5 kW or 10 kW inverter, single or three phase?
The inverter is the box that turns your panels' DC power into the AC your house runs on, and with a battery it also manages charging and backup. A bigger one costs a few hundred dollars more. Sometimes that's well spent and sometimes it buys nothing.
What a bigger inverter doesn't get you
More buyback. Synergy credits exports up to 5 kW under DEBS whatever the inverter size. A 10 kW inverter exports the same as a 5 kW one.
When 10 kW is worth it
- Whole-home backup. A 5 kW hybrid's backup output covers a few essential circuits. To keep the whole house running in a blackout you need a larger unit. See our backup guide.
- High evening load. A battery can only supply as much power as its inverter allows at once. If your house regularly pulls more than 5 kW in the evening (ducted air-con, an induction cooktop, an EV charger), a 5 kW inverter tops up the rest from the grid even with a full battery.
- More panels than a 5 kW inverter can take. Inverters have a limit on how many panels they can run. If your roof and your usage call for more, the bigger inverter is the way to fit them.
If none of those apply, a well-sized 5 kW hybrid is usually the better buy.
Panels vs inverter size
It's normal for the panels to add up to more than the inverter's rating. Panels rarely hit their full rating, and the extra means more output in mornings, afternoons and winter. The federal solar rebate rules allow panels up to 133% of the inverter rating on a solar-only system, and more with a battery, within the manufacturer's limit.
Single phase or three phase?
Most Perth homes are single phase. Newer and larger homes are often three phase. Your meter box or your electrician can tell you which you have.
- Single phase: inverters up to 10 kVA, and a standard connection allows roughly 15 kW of generation.
- Three phase: a three-phase inverter balances power across all three phases and can run three-phase loads like a big ducted air-con. A standard connection allows up to 30 kVA of inverters across the site.
One thing to know with three-phase backup: some three-phase hybrids limit how much backup power each phase can supply on its own. A single large appliance on one phase can hit that limit even when the inverter's total looks big. Ask about the per-phase figure if whole-home backup matters to you.
Western Power has the final say
All of this is subject to network approval. Western Power can limit what's installed at a particular address, which is why every quote should say "subject to site inspection and network approval".
Want the numbers for your house?
Send us your latest Synergy bill and we'll size a system from your actual usage, show every rebate as its own line, and tell you what we can and can't offer before you sign anything.