My electrician suggested a 400 amp panel. He suggested that a solar connection would reduce the amperage rating somewhat. I really was unsure of the need but I went with it. In the end the 400 amp panel required a transformer upgrade from PG&E that head a lead time of more than 2 months. Although the project ran out to the electric date anyway it was a bummer not to know this earlier.

I since have talked to several contractors who said that 400 amp panels are becoming more normal and desirable because of future proofing with electric HVAC and cars. So at first I was unsure but feel like it was the right move for new construction. That said my neighbor has a 200 amp panel with an 11Kilowatt system and has no problem.