New to this realm.. but i want to setup a solar charging station for summer camp.

[ScottRollins]

Our scout troop got a 25watt solar panel donated and i was wondering what I need to also get for it to charge phones and other items. I myself bring cpap batteries, but im sure i can find a outlet somewhere during the day. One person had the idea to get a auto power inverter, but a from things i read already thats not always the best way forward. Being a 25watt panel is it even doable? Will any inverter do?

Thank you for any help

[SunEagle]

Hello ScottRollins and welcome to Solar Panel Talk

To answer your question, a 25w panel will do little to charge a battery that has been discharged. It should keep a small battery on float charge but will not provide more than 1.5 amps which is next to nothing.

I built a small solar/battery system using an 80 watt panel and a 65Ah battery. I really should have gone with a 100 watt panel but at that time it was expensive and out of my price range.

For basics you need to know how many watt hours your loads will use each day to determine the size of the battery, panel wattage and charge controller. On top of that you will need an inverter to power AC loads from the battery.

If it was my money I would go with a small portable power bank that is rated 20000mah. Those are relatively cheap and can recharge a cell phone. They can be charge back up from a laptop or another USB 5volt source.

Even a small experimental solar/battery system can cost you hundreds of $ and provide next to nothing. Just something to think about.

[chrisski]

D4E3CEEE-EEA0-433D-8BA3-19385B7F7D0D.jpegFor scouts, I had a 10 watt solar panel to charge a phone. It took half a day to do so.

I don't know what your devices are rated to, but I have two 10 watt USB plugs on a PWM charger controller. Those are 5 volt 2 amps per USB attachment. A 25 watt panel may look like it works for that, and you could probably try it, if you have a car battery you can sacrifice for it, but would probably drain the battery down quicker than it could be replenished in sunlight. I built a solar generator like that. I have a 100 watt panel that I hook a that PWM charge controller I described earlier. Because a PWM charge controller is inefficient, I think I could probably run 20 watts with this and safely say with a good long day of summer sunshine it would charge my battery and power a few devices.

I'm not the best to be making recommendations, but I'd figure 10 watt hours of power from a battery for each cell phone you want to charge each day. Laptops and tablets, I'm not sure. One thing I saw says a phone charger is 5 watts, and iPad is 10 watts, so the number I mentioned earlier is a bit conservative.

From these scout camping trips, I remember 7 of us adults had USB devices to charge, and to do this, we would have to go the the dining area and plug into power. We tried that 10 watt solar panel I talked about, but unless you left your phone at camp all day, it would not get charged. We had a doctor and a lawyer in the group, and those guys did not get time off and used their phones a bit.

Edit: This is the solar generator I talked about. It's a 100 watt panel with a 400 watt inverter and a 95 ah battery. The battery is not an ideal due to not being deep cycle. With this, I would feel comfortable charging four devices at a time, but at the end of the seven day trip, I suspect my battery may be toast. Also the inverter is way overrated and I would get a smaller 100 watt or even 50 watt and then plug two USB chargers in the two plugs. The next two USBs get plugged directly into two ports on the charge controller. Not the most efficient device, but if you value your cell phone charging, then something like this may work. I remember the camp discouraged scout leaders from using phones, but they were nice for those who really had business that needed to take care of and the one or two scouts that needed that call home to Mom with the first time separation.

I can't upload the pic. huh.

[peakbagger]

I have seen a few setups for cell phones that use those cheap USB 12 volt cigarette lighter plug style power adapters. I used to see them free at trade shows with logos on them (pre CV-19) The input voltage range on them seem to be quite wide. I have never tried it and cant comment on the efficiency but possibly a cheap experiment (preferably with an old cell phone in case it smokes).

[inetdog]

A 25W panel could theoretically provide enough power to charge or even fast charge one phone or slow charge four or more. But not if you have a multistage conversion along the way, such as panel to charge controller to battery to inverter to wall wart. The inefficiencies at each stage will kill you.
On the other hand, a "direct" system from panel to USB charger will only allow you to charge phones one or two at a time and only while the sun is shining.