We reviewed the 5 watt size. It also comes in 10, 20, 30 and 60-watt sizes.
From PowerFilm solar comes a great little charger that folds down nearly to the size of a topo map, weighs less than six ounces, and can charge a number of small batteries simultaneously.
Heavy gear gets left home, but you'll bring the PowerFilm charger along. Folded, it'll easily fit in your pants pocket, or the top of a pack. At $80 from a number of suppliers online, it's a good value that makes a good starter pack for fastpackers short on space and weight. The panel made power as advertised, and did okay in light overcast.
Unlike the Brunton's monolithic construction, the PowerFilm offering is a series of flexible PV panels glued on nylon backing. A good tug peeled up one corner of a panel, which might mean delamination problems down the road, especially if used on a really hot day, or left on the dash. Also, the stitching is a single running stitch, which can tear out completely if snagged. The wiring and adapter seemed needlessly bulky, and a lack of reverse-polarity protection means you could conceivably fry the panel if you did something wrong — not likely but still a possible problem. Solar panels work better when they're cold, so why black fabric backing that heats up in the sun?