What size power station do you need to run a CPAP with heated humidifier overnight?
Short answer: 791 Wh of rated capacity — that's the ~1 kWh — mid-size class. The heated humidifier nearly doubles a CPAP's draw — size for it, or plan to run passover-only.
The math, appliance by appliance
Appliance
Avg draw
Hours used
Energy
CPAP (heated humidifier)
70 W
8 h
560 Wh
Energy needed over 8 hours
560 Wh
÷ 0.85 inverter efficiency
659 Wh
× 1.2 headroom (ageing, cold, overrun)
791 Wh
Recommended: ~1 kWh — mid-size class. Output check: 70 W continuous, 70 W surge.
Fridges and freezers use their average cycling draw for energy and full compressor draw for the output check — that's why the numbers differ from the label.
The bare energy need is 659 Wh after inverter losses; the extra 20% covers battery ageing, cold weather, and outages running long. A smaller unit works on a good day — this size works on a bad one.
What about output watts, not just capacity?
These loads draw 70 W continuously with no motor surges — any unit big enough on capacity is big enough on output.
Could solar keep this running indefinitely?
Roughly 560 W of panels replaces a day's usage with ~4 hours of decent sun at real-world (75%) efficiency. Half that solar doubles your runtime instead of sustaining it.