Solar panels in the backcountry

Hi all
I have a little solar generator I need to operate my CPAP machine while backcountry. I do not function well if I don’t sleep with the CPAP, so I can’t simply leave it behind
My trouble is the solar panel I have. It works well and is pretty rugged, but it’s too big to have on my kayak for expeditions. Does anyone use a flexible or small solar panel they like? I’m looking for one that’s about 100W
Tia!

Goal Zero. Take a look. I have no personal experience. In the hiking and biking communities I am active in, the discussion usually centers on Goal Zero or Anker.

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I’m really interested to see other comments because I am in a similar position.

I too have a CPAP machine and just recently purchased a 160W solar generator, which will power my CPAP for 3 or 4 days. I’ve started to look at 100W folding solar panels as well, something like this:

This fella also uses a CPAP and in this video he shows the solar panel he is using with his CPAP battery set-up: Allpowers 60 watt folding solar panel - YouTube

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I talked with Justine Curvengen (the film maker behind the This is the Sea series, among others) about solar panels. She uses lots of cameras which need lots of recharging. Her take was that the nice days when solar would work well were also when you want to be paddling (and weather days when you take a day off are generally not great solar days). She didn’t know of any way to really waterproof a solar panel on the back deck to charge while paddling. So she just brings lots of replacement batteries or generators (big battery packs) with her.

I do have a Votaic Fuse system that I could put inside a map case and strap to back deck. I think mine is just 10 watts, though. They do say the various parts are waterproof, but I would not trust what they say for conditions that we would find when paddling. That is something I’d watch out for with all brands and models.

That AllPowers 100w folds down nicely! I think that would fit through my hatch opening! I also think that I’d better do a test-pack if my new-to-me kayak before I buy another panel to make sure everything including the battery will fit.

Fair point about charging while paddling. These days I tend to situate and do day trips from one location, so my biggest concern is how to get it all out there. Then again, perhaps if there was a nice way to charge on the go, I’d consider moving daily.

Yes, I have looked at both. Goal Zero is insanely expensive here in Canada at least compared to all competitors. I have a little Bluetti portable power station that works well so far (only 1 season in), it’s just a smaller panel I’m after.

The only one I’ve used is nowhere as powerful as you need. I’ve got a Brunton foldable unit for camera and small electronic battery charging, but it’s only 26 watts (I think). It’s rated as “water resistant” but I’ve had it out in a canoe in the pouring rain and it had no problems. It folds up nicely when not in use.

I’m in Canada too and I also find many of these items to be quite expensive. I picked up a GOLAPS 160W unit for what I think to be a reasonable price.

I’ve also been looking at the price of 60W solar panels and also checking out the folder size. I have an old CD Solstice GTHV, which has a big rear compartment opening, so size isn’t quite the issue for me. The 60W ones I have looked at so far fold down to about 12"x6".

This is someone that I know in Ariz that designs alt power systems. He has folding panels designed for the military.
Might find something interesting on his site.

Rockpals has a 100W panel that folds up nicely. I have had one for about a year, and it has held up fine. Cable ports are well-placed. It folds smaller than the Jackery, and has better cable protection for light rain. About $200. Best Rockpower 100 Watt Portable Solar Panel - Rockpals

Please correct me if I’m wrong, but I read that these panels take a long time to fill the batteries. Even the smaller ones can take a full day in strong sunshine to fill a battery to charge one phone.

That totally depends on the size of the battery (amp hours) and the wattage of the panel trying to fill the battery.
Low wattage panels and large batteries would take a very long time. High wattage panels and a small amp hour battery, it would be filled/charged fast.
It’s all about the right balance.

I work w/ solar panels and a good rule of thumb is 1.5 watts of panel for every amp hour of battery storage. So a 10 amp hour battery should have a 15+ watt panel to charge it in a reasonable amount of time.

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Way too confusing. All I know is from everything I’ve read about reviews of solar chargers for human powered backcountry use is that they are nearly useless for trips under two weeks and all you want/need to charge can be handled with a power bank or two.

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Not sure when we talk amp-hours which voltage we refer to. Lets simplify and talk watt-hours.

How many watts does your CPAP draw? Assuming it is on for 8 hours and you want to recharge on cloudy days as well as sunny, will a hundred watt solar panel suffice? Or are you better off just bringing a second fully charged battery?

For example if it draws 50 watts, you need 400 watt-hours. If a 100 watt panel puts out 40 on cloudy days (I have no idea), then with the built-in inefficiencies of a charger/inverter system you’d run out of daylight. You’d need a 500w panel to do it in a few hours.

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We are talking about two different things here. The amount that the CPAP draws would come from the battery at night, so that means the battery has to be big enough for that draw plus some as you don’t really want to empty the battery totally.
All the panel does is fill the battery back up during daylight hours. Therefore the panel just has to be sized to do that in a relatively short amount of time.

Exactly.

For any decision to make sense, the first thing you need to find out is the CPAP’s draw. Ultimately that times how long you sleep determines minimum battery size and solar capacity.

I know that clean 100w solar cells put out 100w in ideal temps pointing right at the sun on a very clear day; don’t expect that performance in actual use. Battery chargers are maybe 80% efficient. Inverters are maybe 80% efficient. It adds up, and then account somehow for overcast? Unless CPAPs draw a lot less than I think, you are talking some serious solar.

My CPAP draws between 40 and 50w most of the time if I recall correctly. I worked it out before I got my power station (Bluetti AC50S 500Wh/300W Portable Power Station – Bluetti-Ca).
I only used it to power one CPAP this past year, but hoped it would be enough for 2…it will be able to for about 8 hrs. However, that is because my CPAP doesn’t have the ability to run on DC like many do. The next time I upgrade my machine I’ll be getting a specialized one for camping.
I digress. The power station I have maxes out at about 100w while charging, though on a bright sunny day it’s reported 110w from a 100w panel!
My problem is the portability of that panel. It’s ok while in a canoe, though it does act like a bit of a sail at 22"x22". I’m probably stuck with it given the cost of solar, but if there’s a nice foldable option, I’d put it on my “watch for a good sale” list :grinning_face_with_smiling_eyes:

Yes, exactly @LowTech . The 100w panel I have fills my current power station right up on a sunny day, which is enough because I don’t empty it fully each night with only1 CPAP running.

Jeffski, Yes, taking solar power into the back country requires some gear. The three pieces are the solar panels, the solar generator(battery), and the device you want to run. My 300W solar generator recharges in about six hours in good sun with my 100W solar panels. Not a great approach if you are on the move during the day.

If your CPAP machine draws about 40W, it will discharge a full 300W generator in about seven hours, about the same amount of time it will take to recharge the generator. The 300W generator is about the size of a lunch box and weighs about eight pounds.

So you wake up in the morning with an empty generator that needs charging for the next night’s sleep. But you need to stay in one spot with good sun to be about to repeat the cycle. I think these off-grid generator systms work better for off-grid car camping. You can either recharge with the solar panels at a campsite, even setting the panels inside the car windshield to recharge when on a hike to avoid theft. Or recharge when driving to the next campsite.

It would seem smaller solar batteries, typically 1"x4"x8", fully charged might recharge phones and a laptop for a day or two, but the larger systems don’t seem very practical for kayak touring.

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