As it was said in the movie Apollo 13. “Days? They don’t have days. POWER. Everything is power. Without it, they don’t thrust, they don’t power up the LEM. They don’t communicate. Without power, they’re dead, in hours. Not days.” When prepping, some type of power supply, as well as how long it is feasible to maintain needs to be a priority right up there with food, water, defenses (ammo). I can’t imagine prepping for any scenario where my families and my very survival does not rely on some form of power supply. As well as for a somewhat extended period of time for a plan B to be found based on the particular apocalypse. As long as I’ve got juice, I’m pretty sure I can hold my home if SHTF