Ethan BrooksBy Ethan Brooks

Updated November 2026

An off-grid solar system australia setup lets you run a home or shed without a grid connection, as long as the panels, batteries and inverter are sized to your real daily energy use. This guide walks you through the sizing math, the main components and the wiring order so you can plan a system that holds up through cloudy days and long nights. For a broader overview, see What Is Meant by Off Grid Solar System? A Plain-English Answer.

Step 1: Work Out Your Daily Energy Use

Start with a list of every appliance you plan to run. Multiply each device’s wattage by the hours it runs per day to get watt-hours (Wh). Add the totals and then add roughly 20 percent for inverter losses and wiring inefficiency.

Shopping for one? See our guide: 6 Best DIY Solar Power System Kit Options for Off-Grid Homes (2026).

For example, a 12 W LED light running 5 hours uses 60 Wh. A 150 W fridge that runs about 8 hours a day (averaged over its compressor cycles) uses around 1,200 Wh. Your total daily load is the sum of all these figures, and that number drives every sizing decision that follows.

Step 2: Size the Panels and Battery Bank

Australia gets strong sun in most regions, but winter days are shorter and cloud cover varies. A common approach is to use your local peak sun hours (check the Bureau of Meteorology or a solar irradiance map for your postcode) and divide your daily load by that number, then add a margin of 25 to 30 percent.

Battery capacity should cover at least one to two days with no sun. Divide your daily load by the battery’s usable depth of discharge. For lithium iron phosphate (LiFePO4) batteries, many manufacturers specify around 80 to 90 percent usable capacity. For lead-acid, usable capacity is often closer to 50 percent, so you need roughly twice the nominal capacity.

Step 3: Choose the Inverter and Charge Controller

The inverter must handle your peak simultaneous load, including motor start-up surges from pumps or fridges. Choose a continuous rating at least 25 percent above your highest expected running load. Pure sine wave output is the safer choice for sensitive electronics.

The charge controller should match your array’s voltage and current. MPPT controllers are generally more efficient than PWM units, especially when panel voltage is well above battery voltage. Check the maximum input voltage and short-circuit current rating before you connect anything.

Step 4: Wire the System in the Right Order

  1. Mount the panels and run DC cable to the charge controller, keeping runs short to limit voltage drop.
  2. Connect the battery bank to the charge controller first, with a fuse or breaker close to the battery terminal.
  3. Connect the inverter to the battery bank, again with a dedicated DC breaker.
  4. Connect the AC output of the inverter to your distribution board.
  5. Ground the system according to AS/NZS 5033 and the local electrical code.

A single line diagram helps you check this order before you start. See Off Grid Solar System Wiring Diagram Australia: A Step-by-Step Guide for a worked layout.

Parts Checklist

  • Solar panels sized to your daily load and local sun hours
  • MPPT charge controller rated for your array voltage and current
  • Battery bank sized for at least one to two days of autonomy
  • Pure sine wave inverter with surge capacity for motor loads
  • DC and AC breakers, fuses, cable and mounting hardware
  • Earthing kit and surge protection
Component Key sizing factor
Panels Daily Wh divided by peak sun hours, plus margin
Battery Daily Wh times autonomy days, divided by usable depth
Inverter Peak running load plus about 25 percent headroom
Controller Array voltage and current within rated limits

Common Mistakes and Tips

  • Sizing the panels for summer sun only, then running short in winter.
  • Ignoring voltage drop on long DC runs, which wastes energy and heats cable.
  • Forgetting that lead-acid batteries lose usable capacity quickly if regularly over-discharged.
  • Skipping fuses on the battery side, where a fault can deliver very high current.
  • Leaving out a buffer for future loads, such as an added pump or air conditioner.

An MPPT charge controller is worth prioritising because it extracts more energy from the array, particularly in cooler or cloudier conditions. View on Amazon

A monitoring shunt gives you accurate state-of-charge readings, which makes it easier to tune your load habits. View on Amazon

FAQ

How many solar panels do I need for an off-grid home in Australia?

It depends on your daily energy use and local peak sun hours. Divide your daily watt-hour load by the peak sun hours for your location, then add a margin of about 25 to 30 percent.

Do I need a backup generator with an off-grid solar system?

Many owners keep a generator as a backup for extended cloudy periods, but a properly sized battery bank can cover most situations. Consider your local weather pattern and how much autonomy you need.

Should I hire a licensed electrician?

Yes, for any work connecting to your home’s distribution board or for earthing and compliance with AS/NZS 5033. Consult a licensed professional to confirm the design meets local requirements.

Conclusion

A reliable off-grid solar system australia installation starts with an honest load calculation and builds outward from there. Size the batteries and panels to your real use, choose an inverter with surge headroom, and wire in the correct order. Check your design against local codes before you energise the system.

Ready to choose one?

Ethan Brooks

About Ethan Brooks

Ethan Brooks is part of our editorial team and reviews and edits our DIY solar power systems guides, checking product details against manufacturer specifications and owner feedback.