Anker B012YUJJM8 Anker 21W 2-Port USB Portable Solar Char (Open Box)

I am not an expert when it comes to solar panels. I can only talk about my experiences with this product. As with all products I buy on Amazon I thoroughly check out all the reviews. Good and bad. I also check on YouTube to see if anyone has written a review on the product as well. First thing I notice in some of the reviews on Amazon was that people had a hard time charging the Anker 20100 mah power core with this solar panel. That is the power core I have and why I wanted to get the solar panel. I enjoy the outdoors and wanted a way to keep my power core changed and hence, all my toys that I have for hiking and camping. It seems clouds cause the 20100 power core to drop down to a trickle charge and stays there even if the sun comes back out. People had to unplug and plug it back in for it to resume a full charge. I kept reading the reviews and someone found that the Anker 26800 mah dual inport charge power core does not do this and will resume a full charge when the sun comes back out. I also checked the reviews of this solar panel out on YouTube which has several. There was one review that really sold this solar panel for me. It is called, “Anker vs ....”. I’m not going to put the other solar panels manufacturer here but I’m sure you will find it if you look. This guy really put these things through a lot more then anyone will ever do to them. The competitor’s solar panel only had two panels to the Anker’s three that I thought was a little unfair. Other then that, his test was fair across the board. He through them around and tossed them from a height of 20 feet. Left them out in a rain storm and through them both in a pond. He then lite a fire to dry them out that I was sure was going to melt them. He stomped on them and dropped a ten pound rock on each of the panels. His review is what sold me on this solar panel. So, I bought a the Anker 26800 power core and 21W solar panel together. I have not tested this panel out but two times. Both days were cloudy with some sun. Each time I angled the solar panel torward the sun to get the most of it and left it to charge the power core. The first day was more cloudy then the second. On the first day my power core was down to one light and I charged it for about 6 hours. It had three lights lite up at the end of the test which is a charge of 50 to 75 percent to the power core. The second time I charged my power core it was back down to one light again. This time there was a little more sun but over that time became more cloudy. I only charged it for 4 hours this time. See picture of clouds from the start of my second test. In this time it went from one light to two lights on my power core. The best I can figure is that is a 25 to 50 percent charge to the power core which only has 4 lights. So with the two tests done on cloudy days, as close as I can figure, that is an average of about 12 to 25 percent charge to my power core every two hours. I think that is pretty good but like I said before, I’m not an expert. I have two lights on now which is somewhere between 25 and 50 percent charge on the power core itself. I am waiting for an all sunny day to see if I can charge it up the rest of the way so the power core is fully charged. At which time all four lights should go out indicating the power core is fully charged. I will update this review when I have completed this last test. In all, I am very satisfied with this solar panel. Update- I just finished charging my Anker 26800 power core with the solar panel. It was a clear sunny day. I angled my solar panel torward the sun and started charging my power core at 8:30 in the morning. It had two out of four lights lite when I plugged it into the solar panel and the second light started flashing on my power core letting me it was charging. It took 6 1/2 hours for the power core to be fully charged. Over that time I adjusted the solar panel’s angle twice. As far as I can tell the power core charged anywhere from 50% to 75% in that time frame. That is still an average charge of about 25% every two hours. Not a big change from the two cloudy days before. This is a huge power core and I have not drained it in any less than 3 days. I charge my spotlight, headlamp and, my iPhone 5s from this power core. I have also run my two camp lights that are 100 lumens each overnight for about ten hours and they did not even use 25% of the charge from my power core. See picture of the things I have charged. I am very happy with how well this solar panel preformed. It does not seem to have any trouble charging my Anker 26800. I do not see myself running out of juice to power my toys on multi day hiking and camping trips. In order for that to happen, I would have to have no sun for 3 or 4 days. But, this solar panel seems to have the ability for a slight trickle charge on completely overcast days. I will try that next to see how well it works. I may have to limit my use of some things but I don’t see myself running out of power completely. This solar panel has preformed beyond my expectations and I am very happy with it. If I ever need more then one, this is the one I’m going to buy.