I have a 100A old-style circuit breaker main (~1970, 2 conductor & ground) in the basement.
I want to upgrade the circuits in the garage to allow for solar panels and PEV cars, so my thought was to install a new 200A service main outside the basement, turning the old main into a subpanel, and running a new 100-150A subpanel to the garage.
So the garage components, being new would need to conform to NEC 2017 code.
The question is about the old 100 main that would then become a subpanel. Since it wouldn't conform to newer codes, would I need to replace / upgrade it as well to separate neutral and ground. See attached picture below. Neutral and grounds are together on the same bar, and a braided bare copper wire bonds the box to the neutral bar at the inbound conduit. Also there is no copper grounding rod electrode outside at my house.
My gut tells me I have to upgrade this box to new code, but I thought I'd ask.
All responses very helpful, hard to select just one.