How Many Solar Panels Do I Need? Australian Sizing Guide (2026)

Short answer: most Australian homes need a 6.6 to 10 kW solar system, which is about 15 to 23 panels at today's typical 440 W panel size. Work it out from your bill in three steps, then size up if you plan to add a battery, an EV or a heat pump.

Step 1: Find your daily electricity use

Your bill shows usage in kWh for the billing period. Divide by the number of days. Many Australian households use 12 to 25 kWh a day. Use a full year of bills if you can, because winter heating and summer cooling change the picture.

Step 2: Know your sun

A 1 kW solar system produces roughly this much per day on average, depending on where you live:

These are approximate annual averages, lower in winter and higher in summer. Orientation matters too: north-facing roofs produce the most, while east and west roofs produce about 10 to 15% less but spread output across the day.

Step 3: Calculate system size and panel count

System size (kW) = daily use ÷ daily kWh per kW. A Sydney home using 20 kWh a day needs about 20 ÷ 4.0 = 5 kW to match its use on paper.

In practice, size up. You only use 30 to 40% of your solar directly without a battery, and the cost difference between 6.6 kW and 10 kW is modest. Most installers recommend 6.6 kW as a minimum.

Panels = system size in watts ÷ panel wattage. 6,600 W ÷ 440 W = 15 panels; 10,000 W ÷ 440 W = about 23 panels.

Quick reference

Limits that cap your system size

• Export limits: many networks cap single-phase homes at 5 kW of export (some at less). You can still install more panels than that, often up to 6.6 kW on a 5 kW inverter. Ask your installer what your network allows.
• Roof space: each 440 W panel needs roughly 2 m² of unshaded roof.
• Shading: even partial shade cuts output. See is my roof too shaded?
• Three-phase power allows larger systems and higher export limits.

Why bigger is often better in 2026

Feed-in tariffs are low (often 3 to 7 cents), so extra panels earn little from exporting. But they make a battery fill on cloudy days, cover EV charging and power a heat pump hot water system. If any of those are likely within five years, install the bigger system now. Adding panels later costs more.

Check the payback

Put your system size and a real quote into our solar payback calculator, and read Is solar worth it in Australia? for typical prices and savings by city.

Figures are typical estimates, checked November 2026. Your installer should do a site-specific design.