How to size a solar system for your Australian home in 2026.

The 30-second take

• 6.6 kW suits 2–4 person households with average daytime usage — the most-installed size in Australia.
• 10 kW future-proofs for a battery or EV. The sweet spot for most owner-occupied homes.
• 13.2 kW is the largest size that fits comfortably on most three-phase homes. Single-phase grid limits apply in most areas.
• Installed pricing moves with the certificate market and by site — our solar panel cost guide carries the current bands.
• Match system to daytime usage + planned future load (EV, battery, heat pump).
• Bigger isn’t always better — feed-in tariffs are low and falling, so excess production exported at 5–10c/kWh isn’t the value it was in 2015.

The 6.6 kW sweet spot — and why it’s changing

6.6 kW has been the most-installed system size in Australia for the past decade — and for good reason. It fits the standard 5 kW inverter limit on a single-phase home (you can oversize panels by 33% over the inverter rating per CEC rules), it is the size most installed price bands are quoted against, and it produces roughly 25–30 kWh per day on average across most of Australia.

For a 2–4 person household running a fridge, hot water, and normal appliance load during the day, that’s a solid match. The problem in 2026 is that feed-in tariffs have collapsed (5–10c/kWh in most states, vs 20–60c a decade ago), so the value of exported excess solar is much lower than it used to be. That changes the maths in favour of either right-sizing for self-consumption, or going bigger and pairing with a battery.

When to step up to 10 kW

10 kW (24–26 panels) is roughly a 50–80% step-up from 6.6 kW in both array size and cost — current installed price bands are in our solar panel cost guide. The reasons to do it:

• You’re planning a home battery in the next 1–3 years. A 10 kW system gives you the headroom to charge a 10–13 kWh battery during the day and still cover daytime household load.
• You’re planning an EV in the next 1–3 years. A typical EV uses 10–20 kWh per 100 km. Charging at home on solar saves you 30–50% of EV running costs.
• You have or are planning a heat pump hot water system, ducted reverse-cycle air-con, or pool. These all add daytime load that a larger system covers.
• You have three-phase power. 10 kW fits naturally on three-phase without grid-export restriction issues.

When to go 13.2 kW or larger

13.2 kW (30–32 panels) is the largest size that fits comfortably on most three-phase residential homes. On single-phase, grid export limits typically cap you at 5 kW or 10 kW depending on your distributor (Ausgrid, Energex, etc.) — so even if you install 13 kW of panels on single-phase, you may not be allowed to export all of it.

This size makes sense if you have three-phase, a large household load (EV + battery + pool), or are running a small home business. Outside those cases, 10 kW often delivers better $/kWh value because the extra production is either exported at a low tariff or curtailed by your inverter.

The simple sizing framework

Roughly: 1 kW of solar produces 3.5–4.5 kWh per day on average across Australia (more in Zone 1, less in Zone 4). Multiply your system size by 4 for a daily kWh estimate.

Then check your daytime usage. Your electricity bill shows total kWh per day — about 30–40% is typically daytime for a working household. Match the daytime portion to your solar output and you’re self-consuming the highest-value kWh (saving 30–40c/kWh retail) rather than exporting at 5–10c.

Read next

• How much does a 6.6 kW system cost?
• How much does a 10 kW system cost?
• Average electricity usage per day in Australia
• See solar panels (brands + pricing)
• Federal STC rebate calculation
• Home batteries — pairing with solar

Sources

• solarchoice.net.au — system price comparison
• cleanenergyregulator.gov.au — STC zones