solar

How much power does your sleep machine consume?
Does it take AC or DC power?

There should be a placard listing out the wattage (or possibly voltage/amperage). With that, you can calculate the watt-hr used.
- If it uses say 50w, you sleep 8hr and it runs constantly, you will need 400w-hr. (volts * amps = watts if it lists amps)
- If it takes 12v DC power directly, you don't need an inverter but you will need a suitable 12v outlet.
- If it takes 120v AC power you will need an inverter.

Assuming 400w-hr, you will need around 100w of panels assuming no other electrical loads. Typically, if you multiply the rated wattage of the panel by 4, that will be a good estimate of the watt-hr generated per day. You might round up to 125-150w panel, so you have a little fudge factor to account for inefficiencies.

You will also need a battery bank capable of storing that much but you can only use around 50% of a lead acid battery capacity without damaging it so figure 800 watt-hr...round up to 1000watt-hr to account for losses. That's going to be about 85 amp-hr battery bank (@ 12v).

Update with the actual wattage and use duration along with anything else you are running and it's pretty straight forward to update my calculations.

This comes up a lot, and it seems a lot of CPAP machines can run off DC, so you can avoid an inverter if you have the correct machine. And I'm not familiar with machines, but energy consumption seems to vary drastically depending on whether you use a warmer, etc.

In short, we need more details about your setup before we can provide any tuned recommendations.

Assuming you're doing your sleeping at night, I think you need to be concerned with how many batteries you have.

jshupe wrote:
T And I'm not familiar with machines.

I'm amazed at how many people are using them.

If your unit is a Phillips Respironics these adaptors can be used with many to avoid the inverter being needed.
If a different brand or model check the mfr website.
As to power usage, most are 50-70 watts with the higher wattage being for those folks who use the humidifier option.

Do an energy survey to determine how many average amps you use per day. You will need at least double that in battery amp hour storage. Then the panels need to have at least one watt per battery amp hour.

Hi Jack,

Here is a plain English series of articles on solar.

https://freecampsites.net/adding-solar/

Start with an energy audit.

100 watts minimum for the effort. You will need a controller.

Inverter is needed to have 120vac. What are you expecting to plug in?

The 12 Volt Side of Life

The cost of panels is almost nothing nowdays. To me it's more the time to buy and set things up, and because of that, you only want to do it once. Put 200 or 300 watts up there and be done with it. Your batteries will thank you.

Bill