Regalis made shuttles possible to drive as main vessels in campaign mode, but didn't gave any way for restoring energy in batteries.

Any glitchless solution for default shuttles?

I just found out the only solution is to get the shuttle into alien ruins and connect powered artifact holder to docking port. More testing need for more solutions.

Regalis must update the game, since I tried to dock to cities themselves, and it's not working. He must add possibility to recharge batteries in less difficult way, than connecting to artifact holders. Make batteries rechargeable by placing items into them, which disappears after use, so credits in campaign mode must be limited.

You kind of get a warning for using a shuttle as main, though. You can use them this way but it's definitely not the proper choice. It kind of feels like it's added so you can test them, at least for now.