Is it the default specification that even if the base is offline, damage can be applied to items that can be placed on the foundation such as wind turbines, solar panels, and SAM sites?
Is there a way to prevent these from damaging?

I too came here for this reason as well.

yes you need to add any prefabs you want to protect to the config section.. See below an example where I added Quarries
"prefabs": [
"door.hinged",
"door.double.hinged",
"window.bars",
"floor.ladder.hatch",
"floor.frame",
"wall.frame",
"shutter",
"wall.external",
"gates.external",
"box",
"locker",
"mining_quarry"
],

Fantastic, thank you!

Thank you for teaching us! I'll try that setting.