And it retains a full charge for. If you don't mind the extra weight and volume for added versatility, I use the Buddipole powermini2, which is a solar charge controller (supports up to 150 W), battery manager (for Li, Li-Ion, LiPo or PBSu) and power distribution. Combine it with a Powerfilm roll-up panel with a bioenno battery. In SHTF you can collect energy from car batteries or extract it from cars in a camp.
You mean power banks with a very small panel? Not. They are too small unless they are for something that is only used very rarely and has very little consumption. For example, if you can leave it in the sun for a week because you only use it once a week. It's not like a calculator where the drain is so low that a small strip can keep it full.
No, tents tend to come out when you put it in the sun after a few years. First check the units so that you know the difference between Wh, mAh, V, etc., the difference between energy and power. Yes, solar panels are generally not worth it. You won't find many hikers using them.
They are heavier, less efficient and more uncomfortable than carrying an external battery. I learned that I would only use a solar panel if I also used an umbrella most of the time to get away from the sun. For solar energy to work properly, it really has to be in the right condition and I have seen too many people think that if they tie a solar panel to their package, it will work. So I could keep it charged, I think forever with the solar panel, but I would have to reduce usage over an extended period of cloudy days.
A solar panel is rarely worth it, but if you are in a static place, with a big sun, with high energy demands and you can charge devices + packs at the same time, Goal Zero also has quite a reputation. If you look at the price of lithium-ion batteries over time, the price drops every year (with a small exception lately due to supply problems), so you'll probably get one eventually, or just use solar energy when buying a home. If you need an off-grid load, you should choose a larger panel (and still suffer from all the problems listed above) such as the Anker PowerPort. Mine has at least one cool LED flashlight that you will never use and a small strap on the compass to make you feel like you haven't been completely ripped off, but the solar panel itself is basically just for decoration and is marketed to trick you into not buying a cheaper or lighter battery, because the panel doesn't give enough charge to do anything.
A lot of theories are published here, but I built two solar chargers for myself and the batteries in my OS camera. But in almost all cases it's not just a weight saver to bring some better power banks, but it's a huge hassle saver if it's just a battery bank while backpacking. I have this solar inverter, several small power banks (Anker), small solar power banks, BigBlu 3 solar charger and some of those USB cables that have 3 or 4 different ends, so I only need 1 cable to charge various types of devices. I look like the nerd with solar panels and a usb extension (to keep my power bank out of the sun), but mine is still running strong 4 years later.
If there is a better alternative like a small windmill to charge a power bank, I prefer to use it if it is SHTF. But for the average PCT user who enjoys spending a lot of time in cities and even stays in hotels from time to time, I would recommend buying a larger external battery. I can say with some certainty that an Anker power bank with iq charging will not fry your switch, but you won't get the Nintendo brand ones because they are a little expensive. I placed the panel on top of my backpack, facing up, and it worked great: I didn't have to charge my external battery or devices at any of the refueling stops.