You can get solar chargers and battery banks separately, which is usually recommended because you have more flexibilty to swap out either one in order to charge more or hold more. Then you can get those all-in-ones that are usually not recommended because (from what I’ve read):
The solar panel(s) are too small
You have to angle them just right toward the sun
Not waterproof (you wouldn’t necessarily want to strap it to your kayak/canoe)
They often just stop charging after a while, or stop when it’s cloudy and then don’t restart
Add your reason here…
For keeping a few basic items charged (e.g. phone, camera, headlamp) some people just avoid them and carry mutliple battery banks for extended off-grid adventures, but that can potentially leave you with zero power.
Sure, there may be some good units out there to help deal with the “will I have enough power?” question. Still, most solar battery banks suck, but WHY?
I’ve tested several now and it is all about the small amount of voltage produced by the panels and how long it then takes to charge the battery. The ones with multiple fold-out panels are better, but you won’t find anything terribly credible for under $100. Pro tip: Put it in a clear dry bag and strap it to your deck.
I just feel that to make a purchase worth it, I’d have to spend $$$, have at least 6 flaps, keep it mostly dry, paddle in sunny California, and avoid going under bridges and trees. Then maybe I’d get one full charge onto my phone.
In order to have any meaningful charging capacity you need several hundred watts worth of panels. Some cruising sailboats have up to 1000 watts if they can fit them. I don’t have panels on my current boat but I had two 65 watt panels on my old boat and they were definitely small for the size of the battery bank that they needed to charge.
Keep in mind these are for backup emergency power only. They are NOT designed to power a phone or anything else all day. They are for backup battery power in a pinch. Your phone will drain the battery faster than the sun can charge it.
It is a simple energy balance. Energy out is the use of your devices and all the inefficiencies (voltage conversions, charging and discharging, battery drain, resistance). Energy that goes in is a function of solar cell efficiency, sun intensity, angle to sun, shading, array size and hours of available sunshine.
All the factors can be improved to some degree by using more expensive components and/or finding better sun spots and possibly adjusting the panels to be perpendicular to the sun rays. Conversely, cheaper components and smaller array size, will make things worse. Temperature will impact battery capacity.
If your unit isn’t “good enough” it is too small and/or not in a good location and/or not made of good components. Or you are in a cloudy area.
