2nd meter was installed by PG&E. We now get 2 bills - 1 for each meter. I was under the impression that we would get 2 lines, but PG&E said they would only do 1 service drop so we had to connect both panels using a hot gutter.
I don't know which 200A panel was used, neither do I know the cost for install as it was part of the bundled cost. But I paid around $1600 for the hot gutter for material and $2000 to install it, I will PM you the name of that electrician. If you upgrade 100A to 200A they might ask you to move to meet code. If you don't upgrade, the city cannot make you change existing non-compliant items related to the main house as per the state ADU laws.
My architect had put the location of the new panel on the plan which the city approved. The city then gave us a meter release. PG&E also asked for pictures of the location where the 200A will be installed, they approved that location and then the electrician installed the panel.
I called PG&E renovations dept and they opened a case for me and assigned a technician, those guys are good
Since water and gas is not split, I just charge the tenants extra for utilities