6.6kW vs 10kW vs 13kW vs 20kW: Which Solar System Size Is Right for Your Melbourne Home?
A side-by-side comparison of Melbourne's four most popular residential solar sizes — daily output, panel count, power phase and exactly which household each one suits.
As a general guide for Melbourne homes: 6.6kW suits 1-3 person households and smaller homes (~26 kWh/day). 10kW suits 3-5 person family homes with daytime usage, pools or a growing family (~40 kWh/day). 13kW suits larger, high-use homes with ducted heating/cooling, usually on 3-phase power (~52 kWh/day). 20kW suits big households, EV owners, all-electric homes or small home businesses (~80 kWh/day). The right size ultimately depends on your household's actual electricity use, roof space and power connection — which a free site assessment confirms exactly.
Why Getting the Size Right Actually Matters
Solar sizing isn’t about buying “as much as you can afford.” It’s about matching generation to how your household actually uses electricity. A system that’s too small won’t cover your daytime usage, leaving you paying full retail rates for the shortfall. A system that’s too large without a battery or growing usage means more of your generation gets exported at a low feed-in tariff, rather than offsetting your much higher retail rate — quietly slowing your payback period.
The good news: larger systems in Melbourne are usually cheaper per kilowatt than smaller ones, since fixed costs like scaffolding, switchboard work and labour are spread across more panels. That’s why many homeowners size up rather than fit a system precisely to today’s usage — especially if an EV, battery, or all-electric switch is on the horizon.
Side-by-Side Comparison
| Spec | 6.6kW | 10kW | 13kW | 20kW |
|---|---|---|---|---|
| Panel count | ~16 panels | ~24 panels | ~31 panels | ~48 panels |
| Inverter | ~5kW | Sungrow, ~8.5-10kW | ~10kW | ~15kW+ |
| Daily output (Melb. avg) | ~26 kWh | ~40 kWh | ~52 kWh | ~80 kWh |
| Annual output | ~9,500 kWh | ~14,500 kWh | ~19,000 kWh | ~29,200 kWh |
| Roof space needed | ~30 m² | ~46 m² | ~60 m² | ~130-140 m² |
| Power phase | Single-phase | Single or 3-phase | Usually 3-phase | 3-phase mandatory |
| Best suited to | 1-3 person households | 3-5 person families | 4-5 person, high-use homes | Large households, EV, small business |
Daily Output Compared
Approximate average daily generation across the year for a north-facing, unshaded Melbourne roof.
Each Size, Explained
The classic starting point for Melbourne solar — big enough to meaningfully cut a household bill, small enough to suit most roofs and single-phase connections.
One of the most commonly installed sizes for Melbourne family homes — strong daytime coverage for air conditioning, a pool pump, or an EV, with surplus to spare.
Built for high-use households — ducted heating and cooling, a pool, or a large family — usually installed on 3-phase power and an excellent battery pairing.
For big households going all-electric, EV owners, or small home businesses. Requires 3-phase power and sits above the Solar Homes income threshold for most homes.
Single-phase vs 3-phase, quickly
6.6kW and most 10kW systems suit single-phase homes. Some networks cap single-phase export around 5kW, so larger single-phase systems may use export limiting. 13kW and 20kW systems are usually or always installed on 3-phase power — we confirm your exact connection during a free assessment.
How to Decide: 5 Questions to Ask Yourself
Not sure which size fits your home?
Get a free site assessment with your exact recommended size, output estimate and rebates applied.
How Rebates Apply Across Sizes
Most Victorian homeowners installing 6.6kW, 10kW or 13kW systems can access the Solar Homes Program rebate (up to around $1,400 for eligible owner-occupiers) plus the federal STC discount, both applied directly to your quoted price. The Solar Homes income eligibility cap is dropping from $210,000 to $150,000 combined household income from 1 July 2026, so households near the threshold should apply beforehand.
20kW systems can still claim the federal STC discount, but the Solar Homes rebate may not apply if the system exceeds program limits or your household is above the income threshold — we confirm exactly what your system qualifies for in your free quote. If you’re adding a battery to any size system, the federal Cheaper Home Batteries Program currently reduces the installed cost by roughly $3,300 for a 10kWh battery.
Frequently Asked Questions
What size solar system do I need for my house?
Is a bigger solar system always better?
Can I install a 10kW or 13kW solar system on single-phase power?
Does a bigger solar system cost more per kilowatt?
Should I size my solar system for an EV or future battery?
What is the most popular solar system size in Melbourne?
Not sure which size fits your home?
Get a free site assessment with your exact recommended size, output estimate and rebates applied.
