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.
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