Recently bought and tested the Goal Zero Nomad 10 on a mostly cloudy day using the Goal Zero Flip 20 and am very satisfied with how quickly it charged the device given the less than ideal conditions.For context, I live at 4900 ft above sea-level in a high desert, so the UV even on a cloudy day is very high. The Nomad 10 fully charged my Flip 20 (which was completely dead) in just under 6.5 hours. The first hour of charging was clear and sunny conditions, while the rest of the charging time there were thick to partly cloudy conditions. I checked the charging progress on the Flip 20 (it has 4 LED lights to indicate the power level) every hour and even with the cloudy conditions, it was charging to some extent, but, the best charging occurred not surprisingly during the first hour when there were no clouds overhead. I haven't a chance to test it out on a perfectly clear day yet, but, judging from how quickly it charged the Flip 20 the first hour, my guess it would fully charge in 4 to 5 hours in direct sun.Overall, I'm very satisfied with the Nomad 10 so far. After doing a lot of research on portable, low weight solar options, and having great experiences with other Goal Zero products like the Flip 20, I opted for the Nomad 10 because it strikes a good balance of wattage, size, durability, weatherproofness, and weight and I'll be using it primarily for backpacking, bike packing, car camping, and emergency use.The only improvements I think Goal Zero could make would be to find a way to make it fully waterproof (the USB connection point is the only place where water could wreck a power bank or other device that is being charged) and to reduce the weight even more by using titanium for the bracket that holds the Goal Zero brand power banks as well as the adjustable stand. It would add more cost, but the weight savings, especially for backpacking and bike packing where ounces can really matter would be worth it.