| Panel count (typical) | 20 panels at ~440 W each |
| Inverter | 5 kW |
| Typical retail price | $6,300–$8,600 |
| Annual generation | ~9,570 kWh / yr |
| Daily generation | ~26 kWh / day |
| Roof area needed | About 33 m² of north-facing roof |
| Suits | 3–4 people, $300–$600 / quarter |
| Typical payback | 3–4 years |
Federal STC rebate on a 6.6 kW system, by state
The federal STC rebate scales with system size and STC zone. Here's what a 6.6 kW install attracts in each state in 2026:
| State | STC zone | Federal STC rebate | Net price (low end) |
|---|---|---|---|
| New South Wales | Zone 3 | $1,386 | $4,914 |
| Victoria | Zone 4 | $1,189 | $5,111 |
| Queensland | Zone 2 | $1,386 | $4,914 |
| South Australia | Zone 3 | $1,386 | $4,914 |
| Western Australia | Zone 3 | $1,386 | $4,914 |
| Tasmania | Zone 4 | $1,095 | $5,205 |
| Australian Capital Territory | Zone 4 | $1,189 | $5,111 |
| Northern Territory | Zone 1 | $1,627 | $4,673 |
Add state-specific rebates on top where applicable. The ACT and NSW stacks typically reduce net cost another $1,600–$2,500.
How a 6.6 kW system performs day-to-day
On a clear summer day in Sydney or Brisbane, a 6.6 kW system produces around 35 kWh. On an overcast winter day in Melbourne, it might produce 13 kWh. Annual average is about 26 kWh per day.
For most homes, around 30–40% of that generation is consumed at home in real time. The rest is exported to the grid (and earns the feed-in tariff). Adding a battery typically pushes self-consumption to 80–90%.
Who a 6.6 kW system actually suits
We get this question on every specialist follow-up. Quick rule of thumb based on quarterly bill size:
- 5 kW — Under $300 / quarter · 1–2 people
- 6.6 kW — $300–$600 / quarter · 3–4 people
- 8 kW — $500–$800 / quarter · 4–5 people
- 10 kW — $700–$1,000 / quarter · 4–6 people
- 13.2 kW — $900+ / quarter · Large families, all-electric homes, or EV households
These are starting points. Other factors that bump you up or down: daytime usage (pool, EV, electric hot water), planned future loads (EV in the next 2 years pushes you up a size), shading, and roof orientation.
Battery pairing
A 6.6 kW system pairs naturally with a 10 kWh battery. The federal Cheaper Home Batteries Program pays about $258 per usable kWh on the first 14 kWh, tapering above — so the federal rebate alone covers about $2,580 off the battery price. Add NSW's PDRS per-kWh battery incentive or WA's Residential Battery Scheme on top where applicable.
Full Cheaper Home Batteries explainer →
Common questions about 6.6 kW solar
How much does a 6.6 kW solar system cost in 2026?
Fully installed, a 6.6 kW system costs between $6,300 and $8,600 retail before rebates. After the federal STC rebate (around $1,386 in Sydney/NSW, varying by state), most households pay roughly $4,914 to $7,214 net.
How much electricity does a 6.6 kW solar system generate?
A 6.6 kW system generates roughly 9,570 kWh per year on average in Australia — that's about 26 kWh per day. Output varies ±20% depending on location, roof orientation, and shading.
Who is a 6.6 kW system suitable for?
3–4 people households with quarterly bills in the $300–$600 / quarter range. You need roughly About 33 m² of north-facing roof. The most-installed system size in Australia. The 6.6 kW + 5 kW inverter setup hits the sweet spot of federal rebate value, real-world generation, and DNSP approval ease.
What inverter pairs with a 6.6 kW solar system?
A 5 kW inverter is the standard pairing. The "oversized DC" approach (panels rated higher than the inverter) is legitimate — it captures more STC rebate (which is calculated on panel capacity) without significant real-world clipping.
Should I add a battery to a 6.6 kW system?
A 10 kWh battery is the natural pairing for a 6.6 kW system. The federal Cheaper Home Batteries Program pays about $258 per usable kWh on the first 14 kWh (tapered above), knocking roughly $2,580 off the battery price.
Get matched with a 6.6 kW installer
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