Why 100 watts are not equal to 100 watts?
No small portable solar array will be able to charge much of anything. For comparison, my 330W full size panels, each only produce >150W for maybe 4 to 6 hours per day. On a typical sunny day (June 3rd for example, in NJ, 175 degrees, 20 degrees) one of my 37 330W panels produced at most 2.06kWh across the entire day -- from 6am to 7pm.