right now solar panels provide power for the day transitioning to generators through the night only using batteries when they both fail. ( solar > generator > battery) we can call this "backup mode" it is good for charging vehicles, but for a base with a good solar array this is a waste. the extra solar power is lost with the generators charging through the night

what I propose is "solar mode" (solar > battery > generator) using this mode will significantly decrease how much your generators consume when you have sufficient solar panels. in this mode batteries will actively provide power (like a solar panel) while not actively demanding power (only unused solar can recharge them) by doing this the power not used from the solar panels during the day will be used during the night until empty. then the generator can take over (or not because it's day again) and by setting it per battery vehicles can still be charge normally

as for how to represent it in build mode you could replace the ⛽ icon with ☀