Short answer: Durability

Long answer: Look VERY carefully at those listings! And maybe post what you're seeing here? AC drives have a direct mathematical conversion. DC units can only be "approximated" or identified as a "horsepower equivalent" - with different manufacturers handling their own ratings differently...

Get that statement from the service company in writing! Then, go back to the original homeowner with the agreement that you have and make a formal demand. BUT KEEP READING!

For an overhead door, the spring setup counterbalances the weight of the unit. Spring sets are color-coded based upon the loads that they can handle. AND most importantly, this is why all of us everywhere only need to buy ONE particular garage door opener to handle ANY wood or fiberglass or steel or composite garage door of any width or thickness!

THEREFORE, don't remove ANY insulation until formal action is corroborated! The CORRECT fix should "simply" be a spring adjustment or upgrade! If you take it upon yourself to do anything else, ESPECIALLY before asserting a formal demand, then all remedies and expenses could now be yours alone to bear!

[EDIT] Just read through some of the other comments and your notes, here, especially on the insulation type, which is NOT going to be out of line for an overhead door! To doublecheck the "balance" for yourself:

That opener should have a pull-cord disconnect near the door attachment when everything is closed. Disengage it and then try to lift the door for yourself. If it feels like the effort is going to require more than ten pounds of heft; or, if the door travels poorly or binds up within it's tracks, then you'll know for certain that it's a spring or service issue and NOT an insulation issue...

The generator/battery and panel manufacturer(s) - or the local distributors of such components in your area - should have connector options available to go from the exterior to the interior...

Generally speaking, it is a BAD idea to use a hole for temporary cable runs between the exterior & the interior. Most likely, too, it's going to violate at least a code or two...

To answer your original question, though: Yes, absolutely, you can drill a hole through that door in that area...

Bear in mind that you'll most likely be penetrating a very thin steel skin, passing through a foam core, and then encountering another very thin steel skin. Use a sharp bit, NOT elbow grease, or else you'll also be smoothing some sheet metal as well. AND make sure that you drill the correct hole size for the proper CONNECTOR that you'll be using, instead!

Wow! Your municipality seems like a good one, just based on that!

Post & beam construction is a great way to build a structure, open or enclosed! If your five-year plan isn't to enclose & incorporate this current structure, then rethink what you're doing! NOT asking...

Also, 4x4 posts are rarely viable for much more than a deck cover or gazebo. For structural stability - and if it were me and my money doing this - I would purchase a full set of prefab plans that suited my needs, which should include specifications and drawings with footer details as well...

This is a structure that is going to require permitting. And then, in the end, insuring. Relying upon unqualified design work and no specifications is highly unlikely to get anyone to the finish line...

Hoists are a whole other issue, by the way, and really should be investigated separately when an architect or engineer isn't involved. Again, in the end, insurability!

[EDIT] To get a feel for what might be involved, overall, take a look at a more contemporary shelter cover build at a public park. Even if the structure is older and light duty, hopefully it will provide some insight on build quality to better manage your expectations...