Split bus on a MLO residential main service panel

[pv_n00b]

Unless it has a single main breaker it " is" outdated, yet still legal.( having one main is safer all around.) In a neighboring jurisdiction, they make you replace all zinsco panels if you have to alter or add a new breaker. I did not agree with them, but it's in the Coty ordinance, which is allowed to be more restrictive. In my last AHJ they disallowed supply side connections. Perfectly within. The AHJ's rights, to do so. Especially since they have proven not to be as safe. Legal but not the safest or the best for the utility.

Since when have supply-side interconnections been "proven" to be unsafe? What is this proof you speak of? How is it unsafe for the utility? You can't just make a statement like that and not expect to be called out on it.

 

[pv_n00b]

Thank you all, my original call was for the PV company to provide load calcs, as I require with all supply side connections. In the 2020 nec. This particular panel would be illegal. I informed company that our jurisdiction would from now on require MPU's if they encounter this panel. I have an entire subdivision with them.

CA is on the 2019 CEC, not the 2020 NEC so that's not relevant. Increasing the amount of available current in this panel has zero effect on the load so a load calc provides no information relevant to the PV system installation. There are zero reasons to require a MPU upgrade to have a code-compliant PV interconnection here. It's a textbook supply-side interconnection that has no code issues. All the roadblocks you are putting up have no basis in the CEC so I really have to wonder about your motivations.
Now, if this were a load side interconnection in a panel with a main CB and the installer wanted to reduce the main rating to free up some capacity for the PV a new load calc would be a good idea to verify the new CB rating met the code requirements for the load.