By Dave Miller · off-grid sparky · 22 years wiring solar, batteries and sheds in central QLD
“After losing a full day's power when my inverter overheated in the 45-degree heat, I learned that a 90% efficiency rating means nothing without proper shade.”
— Dave. Measure twice, buy once.
ArticlesCalculatorsSite PlannerShopForget the marketing fluff. If you're off-grid in Australia, your inverter isn't just a box—it's your battery's worst enemy. Here's the raw deal on what actually matters.
Forget the marketing fluff. If you're off-grid in Australia, your inverter isn't just a box—it's your battery's worst enemy. Here's the raw deal on what actually matters.
Most inverters suck power even when you're not using anything. That's idle draw. It's the reason your batteries die over winter when you're not home.
Look for under 5W idle draw. Anything above 10W? You're paying for a heater, not power. The big brands (Victron, Epsolar) hit 3-4W. Cheaper Chinese units? Often 15W+. That's 120Wh per day wasted. Over a year? 44kWh. Your solar system could've powered that.
Induction stoves, fridges, and power tools need a surge. Your inverter must handle 2-3x its continuous rating for 1-2 seconds. No bluffing.
Example: A 1000W inverter must surge to 2000-3000W. If it can't? Your kettle dies mid-boil. Cheap inverters often list "surge" as 1000W (same as continuous). That's a lie.
Modified sine wave inverters (common in $300-$500 units) will fry sensitive gear. Your phone charger, laptop, and LED lights will hum, overheat, or die. Pure sine wave? Costs 20% more but is non-negotiable for anything beyond a torch.
Price check: A 12V 1000W pure sine wave inverter (Victron, Epsolar) is $600-$850. Modified sine wave? $250-$400. Don't be cheap here. Your $1000 fridge is worth more than $200 in "savings".
Victron Energy (Venus GX, MultiPlus) - $1,200-$2,500 for 12V/24V pure sine wave. Best for serious off-grid. $1,500 for 1.5kW. victronenergy.com
Epsolar (Pure Sine Wave Inverters) - $600-$900 for 1000W-2000W. Reliable, Australian stock. $720 for 12V 1000W. epsolar.com.au
Renogy (Modified sine wave) - Avoid. $350 for 1000W. Will ruin your gear. $350. renogy.com
Bottom line: Pay $700 for a pure sine wave inverter. Save $300 and lose your fridge. We've seen it. Don't be the bloke with a dead $1,200 fridge because he bought a $300 inverter.
While many off-grid projects are achievable as DIY, certain situations require licensed professionals:
Always check local regulations and obtain necessary permits before commencing work.
Worth a watch: EPIC OFF GRID SOLAR INSTALLATION - VICTRON - PYLONTECH - SOUTH AUSTRALIA · Deionno Electrical
