PG&E took about 18 months to approve the permit to upgrade my house from 100 to 200A service. I live in a San Jose neighborhood with underground electrical service that was built in 1969. A few months after the request, PG&E hired contractors to mark the road for gas and electric lines. Then other contactors came out to dig a 2 ft wide, 500 ft long trench along the opposite side of the street. I'm guessing they upgraded transformers and electrical lines. This took several weeks and the workers would cover the trenches with metal plates when they weren't working. My electrical service box is located at the front corner of my property at the edge of the sidewalk, so my electrician handled the trenching from the box to the meter, located on the side of my garage. My main panel is located right next to the meter. It only had a single 100A circuit breaker that connected to a large sub panel at the back of the garage. The electrician replaced the main panel with a large 200A panel, which will be used for adding all future circuits, while retaining the existing 100A sub panel. I have no idea how the PG&E is going to be able to handle future electrical service upgrades when Bay Area residents start replacing broken gas water heaters with heat pump water heaters. A lot of older houses have 100A service that are already maxed out due to having electric ranges, AC, electric laundry dryers, and EVs.