By Dave Miller · off-grid sparky · 22 years wiring solar, batteries and sheds in central QLD
“After losing two batteries to a DC fridge's 20-amp surge in a central QLD heatwave, I learned to size my bank for peak amps, not just daily watt-hours.”
By Dave Miller · off-grid sparky · 22 years wiring solar, batteries and sheds in central QLD
“After losing two batteries to a DC fridge's 20-amp surge in a central QLD heatwave, I learned to size my bank for peak amps, not just daily watt-hours.”
Let's cut the bullshit. If you're off-grid in Australia, your fridge better have a DC compressor. AC fridges on inverters? Waste of battery and money. Done.
Forget the rest. These are the only DC compressors worth your cash. No exceptions.
Models: SDN, SDC, VD. Common in Aussie off-grid fridges.
Pros: Cheap, reliable, easy to fix. If your fridge dies, you can get a Secop compressor for $300-$500 (but you'll buy a fridge, not the compressor alone). Works fine in 90% of off-grid setups.
Cons: Uses 10-15% more power than Danfoss. Gets hot in summer.
Models: BD, BDV, BDV2. Used in premium off-grid fridges.
Pros: 10-15% more efficient than Secop. Runs cooler. Better for long-term battery savings.
Cons: Costs $200-$300 more for the fridge. Harder to get parts if it fails.
Efficiency Verdict: Danfoss saves you $150-$250 in battery costs over 3 years. But Secop gets the job done without breaking the bank. If you're on a budget? Secop. If you've got cash and want to sleep easy? Danfoss.
Off Grid Solutions (offgridsolutions.com.au)
Secop fridges: $850-$1,200 (100L). Danfoss: $1,100-$1,600 (100L). They'll tell you exactly what you need. No upsells.
Solar Direct (solar-direct.com.au)
Secop: $750-$1,050. Danfoss: $1,000-$1,450. They do the work, you just plug in.
Local Solar Shops (e.g., Solar World, Brisbane)
Prices vary. Always ask: "Is this a true DC compressor?" If they say "yes" but it's a dual-voltage model – run.
Don't pay $2,000 for a fridge that's just a Secop compressor in a fancy box. You'll regret it.
Secop: Get it. It works. It's Australian off-grid standard. Danfoss: Worth the extra cash if you've got it. But don't overpay for "efficiency" on a $500 fridge.
Bottom line: Buy a decent DC fridge from Off Grid Solutions or Solar Direct. Don't mess around. Your battery bank will thank you.
Worth a watch: Should You Buy a 12V DC Refrigerator? · An Old Retired Guy
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.
