Solar Generator Sizing Calculator (Australia)
Size a portable solar generator for Australian camping, 4WD touring and outage backup. Calculate battery Wh, inverter W and panel input W with AU sun-hour data.
Prepared by the Solar Calculator HQ editorial team. Review our formula, source and limitation standards.
Solar Generator Sizing Calculator
How to use this calculator
The Australian solar generator calculator above turns a load profile into the three numbers every spec sheet lists: battery capacity in Wh, inverter continuous power in W, and solar input in W. Enter average load, daily runtime, peak surge and Australian peak sun hours — outputs update instantly.
- Average load (W) — sum the running wattage of everything you’ll run at once. A laptop runs 50 W, a 12 V Engel/Waeco fridge 50–80 W, LED camp lights 5 W each, a CPAP 30–60 W. Phone chargers disappear into the noise.
- Runtime per day (h) — actual run-time. A fridge cycles 8 of 24 hours; CPAP runs the 8 hours you sleep.
- Days of autonomy — most of Australia is sunny enough that 1 day works April–October. Plan 2 days for winter Tasmania, southern Victoria, or wet-season tropical north.
- Peak surge load (W) — the largest single load you’ll start. A 1,500 W kettle, 1,200 W induction cooker, 12 V compressor start 1,500–2,200 W. The calculator multiplies by 1.25 to size the inverter.
- Peak sun hours — BoM / PVGIS averages: Darwin and Alice Springs 5.5–6.2, Perth/Brisbane/Adelaide 4.7–5.3, Sydney 4.5, Melbourne 4.0, Hobart 3.5.
How the math works
Three first-principles formulas:
Daily energy:
daily_Wh = avg_W × hoursBattery capacity (Wh):
battery_Wh = daily_Wh × autonomy / (DoD × inverter_eff)80 W × 6 h × 1 day at 90% DoD and 90% inverter efficiency: 480 / 0.81 = 593 Wh. Round up — 700–1,000 Wh class units are the Aussie touring sweet spot.
Inverter continuous (W):
inverter_W = peak_W × 1.25Solar input (W):
solar_W = battery_Wh / (PSH × charge_eff)At AU average 4.8 PSH and 85% MPPT charge efficiency: 593 / 4.08 = 145 W. A 150–200 W folding panel covers it.
What a solar generator costs in Australia (Q1 2026)
Pricing from EcoFlow AU, Jackery AU, Bluetti AU, Anker SOLIX AU, Outbax, JB Hi-Fi and Bunnings portable-power categories:
| Use case | Battery Wh | Inverter W | Solar input W | Total kit |
|---|---|---|---|---|
| Weekend camping (phone + lights + CPAP) | 300–500 | 600–1,000 | 100–200 | A$500–950 |
| 4WD touring (Engel + LED + small appliances) | 700–1,200 | 1,200–2,000 | 200 | A$900–1,800 |
| Power outage essentials (fridge-freezer + router + lights) | 1,000–2,000 | 1,800–2,400 | 300–400 | A$1,500–3,000 |
| Whole-home critical loads (fridge + pump + lighting circuit) | 3,000–5,000 | 3,000–5,000 | 800–1,200 | A$3,200–6,500 |
| Off-grid expandable (modular packs) | 6,000–18,000 | 4,000–7,200 | 1,200–3,600 | A$6,500–18,000 |
Portable solar generators are sold with GST included; no STC discount applies (those are reserved for CEC-accredited fixed installs).
Where most Aussie solar generator buyers under-size
Three common patterns from the Caravanners Forum, ExplorOz, EcoFlow Australia community and Outbax customer reviews:
- Sizing on running wattage, ignoring surge. A 1,000 W inverter handles a 700 W toaster but trips on a 12 V compressor start. Aussie fridge-freezers and air compressors regularly hit 1,500–2,200 W surge.
- One-day autonomy in southern winter. A 500 Wh kit + 100 W panel works in NT in May. The same kit in Hobart in July gets one 2-hour charge window and dies on day two.
- Cigarette-lighter recharge as primary. A 12 V car port outputs ~120 W. A 1 kWh unit needs 9+ hours of idling to refill — usually faster to spec a proper folding solar panel and DC–DC charger.
Pair this with the off-grid system calculator, battery bank calculator, and caravan solar calculator
This calculator gives the headline three numbers for a portable solar generator. The off-grid calculator scales the same logic to a fixed shack or remote homestead. The battery bank calculator drills into Ah capacity at 12 V / 24 V / 48 V for DIY caravan and 4WD installs. The caravan calculator picks roof-mount panel wattage for fixed van builds.
Sources
- Bureau of Meteorology (BoM) — Solar radiation — peak sun hours by location
- Clean Energy Council (CEC) — accredited installer scheme and approved products
- SunWiz industry analysis — Australian solar market data
- Australian Energy Regulator (AER) — network reliability and outage statistics
- AS/NZS 4509 — Stand-alone power systems — Australian standard for off-grid PV design
- Renewable Energy (Electricity) Act 2000 — STC scheme — federal small-scale certificate framework