To start with I am NOT an electrician and have very little knowledge of electrical loads. We are in the process of a complete remodel of our home, and in order to "future proof" our house, our architect suggested upgrading our electrical panel as well. When I initiated the purchase of my solar system from Tesla in May, 2021, I also started a request to upgrade my existing service panel (main panel) to 400 amps from PG&E. Silly me thought that I would have had the new panel in way before Tesla would come to install the system. Tesla installed the solar system in September, 2021 and we got our PTO in February, 2022. PG&E finally gave us the approval for our panel upgrade in May, 2022. We have a 12.24 kW Solar system with 2 PowerWalls that is attached to our existing electrical panel. I can't get a straight answer from my GC, electrician or PG&E as to what our current service panel is? Some say it is 100 - others say it is 125 and others say it is 170. If that part wasn't frustrating enough, now we are in the process of trenching to install our new 400 amp panel and we noticed that the Tesla backup-switch on our meter says it is only rated for 200 Amps. Initially, we didn't know what this thing was, but we have come to find out that this is what provides our "whole house" to be backed up during a power outage. We recently had a power outage and this sucker worked flawlessly so we DO NOT want to be without it. PG&E doesn't seem to have any knowledgeable folks about what this thing does or how to integrate it with the new panel. I have been trying to contact Tesla for 3 months now to find out if I can use my existing "meter collar/backup switch" on a 400 amp service panel. I have called and emailed Tesla at their energy support email ([email protected]) for months and have not gotten ANY replies. I have asked if we could somehow “split” the 400 amp panel into two 200 amp panels, but PG&E will only allow us to have 1 meter – and if the Tesla backup switch/collar goes on that meter, I would no longer have the “whole house” backed up. I’m wondering if anyone else has come across this situation. We went with the 400 amp service panel because we wanted to have 2 Tesla chargers (we have 1 now). We also will have some upgraded appliances (Sub-Zero fridge; wine fridge). If anyone has a solution or suggestions on what we should do at this point or who I can contact, I’d really appreciate it. Some additional facts: We have underground service and we would have had to trench for 200 or 400.