Determining Bus-Bar Rating for PV Installation
Originally I was wondering if the Mains 225A max. from the label inside the panel box was the rating of the bus bar. Since it seems there are/can be addition labels on the panel interior itself (the black plastic holding the breakers and bus bars), I wasn't sure if I'd have to pull the meter and main breaker to confirm.

Researching Schneider's website, I noted that for 42-space single phase interiors in QO plug-on neutral style there appear currently to only be 225A bus bar ratings available for purchase. While that seems to be a pretty good indicator, I still wanted to confirm a bit more if possible.

I contacted Schneider's technical support to ask if they could confirm that they've only ever sold 225A bus bar interiors for the style/size/phase of my box. The representative wasn't able to do that. But representative proceeded to say in our chat:


  But if you look at the wiring diagram label (should be on the inside of the box on the right or left endwall), it will have a rating along the lines of "Mains max" or somewhere along those lines. That will give you the rating of the bus. It is most likely 225 A, but I can't say for sure without knowing the actual part number


So it appears that you can determine the bus bar rating from the panel box interior label without needing to find a label on the breaker holding interior itself.