Big Off-Grid Solar Design Mistakes Around Ballarat (Read This Before You Build)

People moving to acreage around Ballarat often prioritise the house, fittings, shed and garden—and leave the off-grid solar system to last. A dream home turns into a nightmare the moment the power runs out.

Generators in winter? Yes, you can rely on one—but in practice it’s painful and unreliable. Forget to add fuel or it needs a service and it becomes a constant hassle.

Energy is the #1 investment. Make the energy source your top priority. Whatever system the installer offers, **multiply it by two—ideally three—**if you want a comfortable life.

System design (no compromises)

  • Base load: 10 kWh just to cover the house (no people).
  • People load: add 5 kWh per person, and always size for at least four people—even if there are only one or two of you now, the house may be on the market one day.
  • Comfortable daily use: ~30 kWh/day. Ignore the “Australian average” of ~20 kWh/day—you’re not on the grid.

Battery and solar sizing for Ballarat conditions

  • Battery bank: 90 kWh for three days of autonomy (ideal, not a compromise).
  • Winter reality: in Ballarat (and Gippsland) you can have ~2 hours of usable sun in winter.
  • Solar array: design to recharge 90 kWh in ~2 hours → about 45 kW of solar (usually rounded to 50 kW).

Inverter and topology

  • Inverter power: around 25 kW to comfortably pair with ~50 kW of panels.
  • Peak demand: ~50 A peak covers most homes.
  • Redundancy: build two parallel systems for reliability.

Ideal off-grid setup for a Ballarat home

50 kW solar + 90 kWh batteries + 25 kW inverter, built as two parallel systems.

Cost guide (with current rebates)

  • Shed/roof mount: $80k–$90k out of pocket if your shed can take ~100 panels (each about 1.9 m × 1.16 m).
  • Ground mount: $95k–$120k, depending on ground conditions.