Since other people have already had my idea about solar hats here's the other power production idea for people on the run... literally! kinetic Boots (or pants): by combining some basic things like an generator, circuits, and other gizmos the player could make some clothing that generates power as they walk around, making those long walks through winding mineshafts help recharge their batpacks for some more digging!
Based around an pair of iron pants or rubber boots the kinetic power would be rather low voltage, but would help with charging batpacks and possibly even electric jetpacks, and helps keep off any unwanted pounds that extra porkchop might be putting on!
An approximation of the recipe I had in mind for the basic set, tho advanced generating clothing could be an option? Presuming all this is able to be scripted...