In reply to cmr132: and tjin
mobilesolarchargers.co.uk panel and batteries (power banks) specs look great and plus 25 w.
My experience is on expeditions/outings that the sun is seldom (never) shining. And if it there is sun you don't need power. When there is no sun then you need most of power for your satellite phone (mind the plug) which is a drain. So go big and turn it of power consumption is enorm.
But first of all: make less or no calls. (Others will do though for you! We split the costs.)
Goal zero 17 w is good with power bank. I used before Burton flexible panel also 17W? no power bank, and had weak connector points, but light weight. Would go now for bigger. mobilesolarchargers.co.uk stuff looks quite sturdy? on the picture.