Question on solar panel usage. Looking to get a jackery powerbank for a fridge/freezer. For anyone who has powerbank/panels/fridge, do you use the panels to charge the powerbank or your vehicle battery? I'm less interested in USB phone charging potential. Just not sure which power source I need to charge. Is solar even a requirement with a 2-3 day capability of the powerbank? (for a 2-3 day trip, that is).