How this is calculated
Energy per night is average watts × hours, times 1.15 if you run through an AC inverter — the conversion loss plus the inverter’s own idle draw. The manufacturer’s 12V/24V DC cable skips both, which is why it’s the first thing experienced off-gridders buy.
The wattage presets are averages across a night at typical pressure settings; your machine’s data sheet lists exact figures, and higher pressures sit at the top of each range. The battery figure is usable watt-hours — energy that actually comes out of the pack — times your nights of autonomy.
The humidifier is the whole story. The blower itself sips ~10W; the heater plate multiplies that by four or more. Off-grid, many users switch to a waterless heat-moisture-exchanger (HME) filter or run the humidifier passively (unheated) — same mask, a quarter of the energy.
- This is a medical load: size for your worst stretch of weather, not the average — and keep a charged backup path. The medical & critical loads guide covers layered backup properly.
- Registered CPAP users qualify for priority restoration with many utilities — worth doing even after you’re energy-independent.
- Cold bedrooms raise humidifier draw (bigger temperature lift) — insulate the hose before upsizing the battery.
Building a bedroom-scale kit around it? The power station calculator adds the phone, lights and fan on top.
Quick answers
How many watts does a CPAP use?
~10W with the humidifier off; 30–50W with a heated humidifier; 50–60W with a heated tube too.
How long will a 300 Wh power station run one?
About three 8-hour nights with the humidifier off — or barely one night with it on. Turn the heater off and the same battery quadruples.
How much solar makes it indefinite?
A 50W panel covers a humidifier-off night in average US sun; 120–200W with the humidifier on. Two nights of battery buys cloudy-day margin.