Review on ECEEN 20W Solar Charger Portable Panel With 2 USB Outputs, Waterproof Foldable Phone Charger For Camping Survival Gear Emergnecy Kit, Tablet GPS IPhone Camera & USB Devices by Christine Turner

Durable for backpacking. In the sun, it charged phones about as quickly as they charge while plugged in at home. Maybe faster. Roughly 1% per two minutes maybe. The phones seemed to charge so quickly they thought they were 100% early but needed to be plugged a while longer lest they drop back down to 90% after 10 minutes unplugged. We used an external battery pack to charge more gradually. On a cloudy/rainy day, we picked up a fair amount of charge from inside our double-wall tent. Not as fast, but I'd guess it'll charge a smartphone 0-100% in 12 hours.The nylon folder-like thing holding it seems a little too heavy for ultralight backpacking, but I admit the durability was nice. While flipping the panel over to plug things in, I had the panel scraping on rocks, and there was no apparent damage to the sleeve or panel. I imagine you could lighten the while thing up by cutting parts of the nylon off, but I might keep it on just for the durability and because I don't know where the wiring is inside. And it's nice to have some rigidity when stuffing this into a packed backpack and dragging it through horrendous off-trail conditions. The little string loops on the four corners are great for hooking to things to keep the panel from blowing over or blowing away in the wind. There are two USB plugs in the back. I suspect those will be the first part to fail.