We hired an Iridium Sat Phone when we were doing a self-drive safari in Namibia and Botswana, which involved being way off the beaten track, and they have the look-and-feel of an '80s 1st generation mobile phone, and a power consumption to match.
They charge OK from a vehicle 12v supply, but a teensy solar array is not really going to cut it.
You'd need a solar array the size of a football pitch, or carry a small generator and some jerry cans on your bakfiets!