What Size Solar System Do I Need for a CPAP?

The wattage chart is a range, and heated humidity is a second range. An 8-hour night is the example input on this page — replace it with the hours you actually sleep.

Full breakdown: what size solar system.

If you already own the battery and need the recharge rule of about 200 W per 100 Ah, use how many solar panels to charge a battery.

Quick answer: Champion lists a CPAP at 30–60 W, and 60–120 W when it is heated. Held for an example 8-hour night, that is 240–960 Wh. At 4 peak sun hours the bare array is 60–240 W, and Battle Born's 20 to 30 percent makes it about 72–312 W. Measure the machine. Then check sun at your address in PVWatts or the solar size calculator.

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Watt-hours, then array watts

Case	Chart watts	× 8 h	4 h sun: bare / +20–30%	5 h sun: bare / +20–30%	Phoenix Dec 4.75: bare / +20–30%	Source
Low, unheated	30 W	240 Wh	60 / 72–78 W	48 / 57.6–62.4 W	50.5 / 60.6–65.7 W	Champion; hours are the example input; array Battle Born; December sun PVWatts
High unheated, or low heated	60 W	480 Wh	120 / 144–156 W	96 / 115.2–124.8 W	101.1 / 121.3–131.4 W	Champion; hours are the example input; array Battle Born; December sun PVWatts
High, heated	120 W	960 Wh	240 / 288–312 W	192 / 230.4–249.6 W	202.1 / 242.5–262.7 W	Champion; hours are the example input; array Battle Born; December sun PVWatts

The 8 hours is this page's example input, stated so the multiplication can be checked. It is not a sleep prescription. 60 W appears at the top of the unheated range and at the bottom of the heated range, so it is one row, not two machines.

How to size it

Champion gives watts. Battle Born turns watt-hours into array watts. The missing piece — how long the machine runs — is the example, because neither source publishes a CPAP night length.

Pick a wattage inside the chart: 30–60 W, or 60–120 W heated. 120 ÷ 30 = 4, so the top of the heated range is 4 times the bottom of the unheated range. The array scales by that same factor if the hours stay fixed.
Example night: watts × 8 hours. 30 × 8 = 240 Wh. 60 × 8 = 480 Wh. 120 × 8 = 960 Wh.
Divide by peak sun hours. At 4: 240 ÷ 4 = 60 W, 480 ÷ 4 = 120 W, 960 ÷ 4 = 240 W. Add 20% and 30%: the low machine becomes 72–78 W and the heated high becomes 288–312 W.
Repeat at 5 peak sun hours, and at Phoenix December 4.75 (annual plane-of-array for that run is 6.54, which is the wrong divisor for a winter check).
Battery, from the battery article: watt-hours ÷ 12 V. Two days doubles the amp-hours. A 240 Wh night is 20 Ah for one day; a 960 Wh night is 80 Ah.

Battery at the example voltage

Night	One day at 12 V	Two days	Source
240 Wh	20 Ah	40 Ah	Wh ÷ 12 V; two days doubles
480 Wh	40 Ah	80 Ah	Wh ÷ 12 V; two days doubles
960 Wh	80 Ah	160 Ah	Wh ÷ 12 V; two days doubles

About 200 W of solar per 100 Ah is the lithium recharge guideline, not a third CPAP wattage. A one-day bank for the 960 Wh heated case is 80 Ah, so that guideline would point near 200 W of array per 100 Ah of battery — a different question from 960 ÷ 4, and the one the panels-to-charge-a-battery page is for. Size the bank itself on the battery bank sizer.

A Kill A Watt-style meter is the right next measurement: the chart's spread from 30 W to 120 W moves the array from about 72 W to about 312 W at 4 peak sun hours with margin. After you have watt-hours, use the solar size calculator and PVWatts.

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FAQ

How many watt-hours is one CPAP night on this page?

The example input is 8 hours. 30 W × 8 = 240 Wh, 60 W × 8 = 480 Wh, and a heated 120 W × 8 = 960 Wh. Champion's ranges are 30–60 W and 60–120 W heated.

What array is that at 4 peak sun hours?

240 ÷ 4 = 60 W, then 72–78 W with 20 to 30 percent. 480 ÷ 4 = 120 W, then 144–156 W. 960 ÷ 4 = 240 W, then 288–312 W.

What battery does the 12 V example imply?

Watt-hours ÷ 12 V is 20 Ah, 40 Ah, or 80 Ah for one day at 240, 480, and 960 Wh. Two days doubles those to 40, 80, and 160 Ah.

Which wattage should I plan around?

The chart runs from 30 W to 120 W. 120 ÷ 30 = 4, so guessing wrong inside the range multiplies the array by as much as 4. Measure your machine and replace both the watts and the example 8 hours.

Sources

Champion Power Equipment, Generator Wattage Chart — accessed Oct 2, 2026.
Battle Born Batteries, How to Size Solar Panels for a Deep Cycle Battery System — accessed Oct 2, 2026.
Battle Born Batteries, How to Size a Deep Cycle Battery Bank — accessed Oct 2, 2026.
NREL/NLR PVWatts Version 8 API documentation — accessed Oct 2, 2026.
PVWatts calculator — accessed Oct 2, 2026.