Thanks for the suggestion but the pack top solar power panels I have looked at typically weigh well over a pound. For the way I use a cell phone on the trail (music, Kindle app and Inreach keyboard) I need about one charge per week. I already have a rechargeable 6400 mAhr battery pack that will give me two full recharges. It weighs 4.4 oz. and gives me about three weeks of phone use starting with a fully charged phone. I am hoping to lighten from that. Two non-rechargeable lithium cells weigh about 1.5 oz and should recharge an iPhone at least once. I am hoping to find something that weighs around 2.5 oz with lithium cells. There are roll-your-own chargers in this range: I’m hoping for a manufactured version. The solar arrays are too heavy for my level of phone use.