For anyone on the fence regarding buying a small portable solar panel — take a good look at the Renogy E.Flex5 — relatively inexpensive, $23.98 on Amazon — mine arrived yesterday.

The panel is a small, lightweight, simple design with no moving parts. There is a single USB port mounted on the rear with an output of (5 volts x 1 amp =) 5 watts max, which with good sun should be enough to charge most cell phones — when I hooked up my iPhone 6s Plus just now it immediately went into charging mode. I’ll run it up to ~90% and unhook it. Rough charging rate with the iPhone: it charged from 65% to 72% in 20 minutes — ~1% every 3 minutes in good sun. That should be excellent in an emergency.

After I charge the iPhone, I’ll hook up my Anker PowerCore+ Mini, 3350mAh Portable Charger.

The panel is hyper-portable, small, thin & lightweight. It should be great for emergencies, or to have while hiking and sensitive to extra ounces. This may become my primary hiking set-up for small, lightweight power — small solar panel to keep a small power bank charged, or hook-up directly to the cellphone or GPS (if it can take a USB input).

Note: I unhooked the phone at 82%, 50 minutes from 65%. So 17% in 50 minutes is still still about 1% every 3 minutes with an iPhone 6sPlus. The percentage charge should be quicker with the smaller flip-phone I carry when out & about. YMMV