Panels per system size
Residential panels sold in 2026 are mostly 440 W, so divide the system size by 440 W and round up. The count sets the roof area at about 2 square metres a panel including the gaps between rows, and the price column is the national standard installer offer from the October 2026 index.
| System | Panels | Panels as kW | Roof area | Price, standard offer |
|---|---|---|---|---|
| 5 kW | 12 | 5.28 kW | 24 m2 | $5,550 |
| 6.6 kW | 15 | 6.60 kW | 30 m2 | $6,774 |
| 8 kW | 19 | 8.36 kW | 38 m2 | $7,983 |
| 10 kW | 23 | 10.12 kW | 46 m2 | $9,810 |
| 13 kW | 30 | 13.20 kW | 60 m2 | $12,465 |
A 6.6 kW system is 15 panels on a 5 kW inverter: the panels are oversized by a third because the STC rules allow it and the inverter is the cheaper part. That is why 6.6 kW, not 5 kW, is the size to price first on any roof with room for 15 panels; the 6.6 kW guide has the city prices.
The count by state: output per panel from Hobart to Darwin
One 440 W panel makes 562 kWh a year in Hobart and 707 in Darwin, from the Bureau of Meteorology solar exposure for each capital. The table gives the system size and panel count that generates 4,000, 6,000 and 8,000 kWh a year, which are a small, typical and large household's annual use. It is a generation match, not a bill match: without a battery about 35 per cent of that output is used at home and the rest exported, so most households size above their annual use rather than to it.
| State (capital) | Yield per kW | For 4,000 / 6,000 / 8,000 kWh a year | 6.6 kW makes |
|---|---|---|---|
| New South Wales (Sydney) | 1,424 kWh | 2.8 kW, 7 panels / 4.2 kW, 10 panels / 5.6 kW, 13 panels | 9,398 kWh |
| Victoria (Melbourne) | 1,314 kWh | 3.0 kW, 7 panels / 4.6 kW, 11 panels / 6.1 kW, 14 panels | 8,672 kWh |
| Queensland (Brisbane) | 1,533 kWh | 2.6 kW, 6 panels / 3.9 kW, 9 panels / 5.2 kW, 12 panels | 10,118 kWh |
| South Australia (Adelaide) | 1,533 kWh | 2.6 kW, 6 panels / 3.9 kW, 9 panels / 5.2 kW, 12 panels | 10,118 kWh |
| Western Australia (Perth) | 1,606 kWh | 2.5 kW, 6 panels / 3.7 kW, 9 panels / 5.0 kW, 12 panels | 10,600 kWh |
| Tasmania (Hobart) | 1,278 kWh | 3.1 kW, 8 panels / 4.7 kW, 11 panels / 6.3 kW, 15 panels | 8,435 kWh |
| ACT (Canberra) | 1,570 kWh | 2.5 kW, 6 panels / 3.8 kW, 9 panels / 5.1 kW, 12 panels | 10,362 kWh |
| Northern Territory (Darwin) | 1,606 kWh | 2.5 kW, 6 panels / 3.7 kW, 9 panels / 5.0 kW, 12 panels | 10,600 kWh |
Read your annual kilowatt-hours off the last four bills, pick the column, then round up to the next standard size, because the step from 5 kW to 6.6 kW costs $1,224 nationally and adds 3 panels.
Roof, shade and the direction the panels face
A north-facing pitch gives the yields in the table. East or west faces lose part of the annual output but spread it into the morning or afternoon, which raises the share used at home; a split array across two faces is common on 23-panel systems. Shade from a chimney, a neighbour's tree or a parapet for part of the day costs more than the shaded panels alone on a string inverter, which is the case for microinverters or optimisers on a complicated roof. The roof reader on this site measures the usable faces of an address from aerial imagery and reports the panel count that fits.
Network rules also cap the count in practice: most distributors allow 5 kW of inverter per phase to export without conditions, so a single-phase home above 6.6 kW of panels usually needs an export limit or a three-phase upgrade, costed in the three-phase guide.
Panel count questions
How many solar panels do I need for a 6.6 kW system?
15 panels at 440 W, which is 6.60 kW of panels on a 5 kW inverter and about 30 square metres of roof.
How many solar panels do I need in Tasmania?
11 panels (4.7 kW) generate 6,000 kWh a year in Hobart at 1,278 kWh per kW, against 9 panels in Brisbane, because Hobart has the lowest yield of the eight capitals. A 6.6 kW system of 15 panels makes 8,435 kWh a year in Hobart.
How many panels is a 10 kW solar system?
23 panels at 440 W (10.12 kW of panels) on about 46 square metres of roof, usually across two roof faces.
How many solar panels do I need for a family of four?
10 to 13 panels in Sydney, for a household using 6,000 to 8,000 kWh a year, which is the usual range for four people with electric hot water or air conditioning. Most such homes buy 15 panels (6.6 kW) or 23 (10 kW) and export the surplus.
How much roof space do solar panels need?
2 square metres a panel including gaps: 30 square metres for 6.6 kW and 46 for 10 kW, on faces that are north, east or west and clear of shade for the middle of the day.
What size solar system do I need for my bill?
2.8 kW generates 4,000 kWh a year in Sydney and 5.6 kW generates 8,000, so read the annual kilowatt-hours off your bills, find the state row in the table, and round up to the next standard size. Sizing above your use is normal because only part of the output is used at home.