Costs & savings

How much does a 6.6 kW solar system cost in Australia?

Between about $5,500 and $8,500 fully installed in 2026, with the federal rebate already taken off, and an average close to $6,400. That buys 15 to 17 panels on a 5 kW inverter producing around 25 kilowatt-hours a day. The part worth understanding is why one quote lands at $5,500 and the next at $8,500 for what is nominally the same system.

By Kieron Taylor, Founder, Solar Select · Updated · 6 min read

The 30-second take

  • $5,500 to $8,500 installed for a 6.6 kW system in 2026, rebate deducted. Solar Calculator’s 2026 average is $6,407; the working rule of thumb is about $1,000 per kW.
  • 15–17 panels at 400–440 W each, paired with a 5 kW inverter. 6.6 kW is the most panels the Clean Energy Council rules let you put on a 5 kW inverter, which is why it became the default size.
  • About 25 kWh a day averaged across the year — nearer 28 in Brisbane and Perth, nearer 24 in Melbourne.
  • STC rebate worth roughly $1,700–$1,900 in most metro postcodes in 2026, already inside the quoted price. It drops again on 1 January 2027.
  • Solar Calculator puts typical annual savings at $1,100 to $1,800 for a 6.6 kW system; where you land depends on how much of the output you use during the day.

The 2026 price

Australian solar is priced per kilowatt of panels, and the working number in 2026 is about $1,000 per kW fully installed with the rebate deducted. On that basis a 6.6 kW system sits between $5,500 and $8,500 for good components and a proper installation. Solar Calculator’s 2026 average is $6,407; our own cost guide, which draws on the same published sources, uses $5,000 to $8,500 for the range.

Every one of those figures already has the federal rebate taken off. Australian installers advertise the after-rebate price, so a quote that looks $1,800 cheaper may just be one that has applied the rebate where the other has not. Confirm it before you compare.

What 6.6 kW actually is

6.6 kW is not a round number by accident. Single-phase homes in most Australian networks are limited to a 5 kW inverter, and the Clean Energy Council rules allow panels to be oversized by a third above the inverter rating. Five times 1.33 is 6.65, so 6.6 kW of panels on a 5 kW inverter is the most solar a standard home can install without a network application for something larger.

In 2026 that means 15 to 17 panels, depending on whether the installer uses 400 W or 440 W modules, on roughly 30 square metres of roof. The inverter clips output on the sunniest hour of a summer day and the oversizing more than pays for that with better production in the mornings, evenings and winter.

What it produces and saves

A 6.6 kW system produces around 25 kWh a day averaged across the year in most of Australia. Solar Calculator’s city figures run from 23.8 kWh in Melbourne to 27.7 in Brisbane. That is close to a typical household’s entire consumption, which is where the misunderstanding starts.

A house only uses the solar that is generated while someone is home to use it. For a working household without a battery that is roughly 30 to 35 per cent of the output; the rest is exported at a feed-in tariff of a few cents. Solar Calculator puts typical annual savings at $1,100 to $1,800, and the spread is almost entirely the self-consumption share. Payback at the 2026 price is therefore three to six years for most homes.

“The same 6.6 kW system saves $1,100 a year in one house and $1,800 in the house next door. The panels are identical; the difference is who is home at midday.”

The rebate, by zone

The federal rebate is delivered as small-scale technology certificates. A system earns its size in kW, times the Clean Energy Regulator’s zone rating for the postcode, times the deeming period, which is five years in 2026. A 6.6 kW system in Sydney, Melbourne or Adelaide (zone 3, rating 1.382) earns about 45 certificates; in Brisbane (zone 3 as well) the same; in Darwin or Alice Springs (zone 1, 1.622) about 53; in Hobart (zone 4, 1.185) about 39.

At a certificate price of $36 to $39, that is roughly $1,700 to $1,900 off a metro install in 2026, down from about $2,100 the year before. The deeming period drops to four years on 1 January 2027, which takes another few hundred dollars off. The rebate is set by the installation date, not the quote date.

Why quotes for the same size differ by $3,000

Two 6.6 kW quotes can be $3,000 apart and both be legitimate. The gap is in seven things, and cheap quotes get cheap by trimming the ones you cannot see from the ground.

  • Panel and inverter tier. A 25-year product warranty from a manufacturer with an Australian office costs more than a 12-year one from a brand that may not be here in 2035.
  • Racking and roof type. Tile roofs, steep pitches, two-storey access and coastal wind ratings all add labour and hardware.
  • Switchboard work. Older boards often need an upgrade before solar can connect. Confirm in writing whether it is included.
  • Employed crew or subcontracted at the lowest bid. The Clean Energy Regulator’s inspection programme keeps finding that installation quality, not hardware, is where systems fail.
  • Monitoring, aftercare and a workmanship warranty from a company that will still exist to honour it.
  • Whether the rebate is in the price, and at what certificate price it was calculated.
  • Exclusions. Meter changes, tile replacement, three-phase work. The cheapest quote usually has the longest list.

If your daytime usage already fills a 6.6 kW system, or you are planning a battery or an EV, the next step up is worth pricing at the same time — our 10 kW price guide covers when it makes sense.

Get matched with 2-3 vetted solar installers — typically 2+ years in business, with a track record of decent reviews — ask all of them whether the rebate is already in the price, and let them compete on the comparison rather than on the discount.

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Sources

Every quantitative claim on this page traces to one of the sources below — government, manufacturer, or independent AU industry reference. Last verified 2026-09-18.

We use AI to help research and draft. Claims are traced to the sources below and dated. Where we haven’t got a source, we say so on the page — treat that as a starting point and do your own research.

General information only. It doesn’t take your circumstances into account and isn’t legal, financial, insurance or electrical advice. Rebates, tariffs, network rules and product terms change — confirm anything you plan to rely on with your installer, insurer, retailer or distributor, and see our terms.

Postcode in, up to 3 vetted installers out. Free for homeowners, no obligation. All solar guides · Federal rebates · How it works

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