Lots of shit different back in the day, including my hairline..Back in 'That Day', I may have had a couple of these in my bag of tricks. 'That Day', was a ways back, like 53 years or so, before they got all sophisticated and shit.
I was checking with my kid the other day on a panel upgrade from 100A to 200A for a solar install, about $ 3,500. BUT, that's only to increase the buss rating to at least 125A, if the solar was large enough to require a 50A breaker.
The home I was inquiring about, had an UG service, which in order to increase the conduit size to accommodate increasing service capacity to 200A, would easily more than double that cost.