Bests & Worsts Reviews from Amazon

I'm using this with an EasyAcc 26000mAh power brick. My first test of the panels was on a mostly cloudy day when my power brick was charged in the 26-50% range. It charged up to the 51-75% range after about 4 hours of indirect sunlight, using both cables. My second test was on a very sunny day. My pack was drained back down to the 26-50% range and was fully charged after about 4 hours in direct sunlight, using both cables. I do not recommend using the provided pouch on the panels to store your device, as the heat there can be excessive. Get some longer USB cables so that you can move your device away from the panels - they do get quite warm. I did not see the problem some people have talked about where the panels quit charging until unplugged and then plugged back in. On the mostly cloudy day, I did have a few short periods of direct sun mixed in with the clouds. I watched the charge light on the panels and it stayed red the entire time. My EasyAcc brick was receiving a charge the entire time. So far I am very pleased with this kit and would recommend for anyone who might want to dip their toe into solar power. UPDATE: I have been able to actually measure the power output of the panels now, with a Drok USB tester. As you can see in the photos, in direct sunlight I was getting 4.4 to 4.5 amps in direct sunlight, which is a bit higher output than advertised (21w/5v = 4.2 amps). A bit of shade drops the output down into the 2.5 to 3 amp range and complete overcast will produce from .5 to 1 amps. As expected the angle of the panels affected power output as well, with around 45 degrees to the current sun azimuth producing the highest output.