The main panel no longer has an issue with the 120% rule. The main service is now being fed by the 100 amp breaker located in the sub-panel. The sub-panel is being used as the combiner for the two inverter 20 amp breakers and is connected directly to the bottom of the meter base.
What you are calling the subpanel is now actually the service panel, and vice versa. The service disconnecting means (there are three) are now located in the panel on the right side of the picture.
Another concern is what is the combined amperage at the conductors and bus-bar of the sub-panel being it is connected directly to the meter base of the main service?
This is not a concern in the current setup. The house cannot draw more than 100A load regardless of source. The solar cannot output more than 40A. These do
not add together. The panel won't see more current than 100A.
The sub-panel now becomes an issue without an main disconnect, concerning the 120% rule.
I see now this has been discussed, but I'll expand on it anyway...
The panel on the right is the service panel now, and the solar is connected as supply side connections, and therefore not subject to the 120% rule. Read the 120% rule again carefully; it refers to the sum of solar and the breaker protecting the busbar. The 100A breaker is NOT protecting the busbar; it is protecting the feeder to the original panel and everything beyond that.
My concerns are:
1-voiding the listing of a listed assembly by removing the factory installed conductors between the meter socket and the main disconnect in the original main service ;
2-the grounded conductor is not installed with the un-grounded conductors to the sub-panel, which is now the service panel?
3-service raceway between the existing main service and the "new" main service is not service bonded.
4-neutral bus-bar in the "new" service is not bonded to the panel.
5-neutral bus-bar in the old main service which is now the (sub-panel) needs to be isolated from the ground bus-bar.
6-a 100 amp overcurrent device is required at the "new" main service to protect the bus from not more than 120% of the rating of that bus-bar which is 125 amps.
7-the "new" main service must be service rated.
Don't need to repeat everything that's been said, I agree with electrofelon, but a couple more comments.
1) This could depend on what the manufacturer or NRTL says.
2) This represents an actual inductive heating problem. Not good. Violation of 300.20(A).
5) Might be problematic from the listing point of view, too.
Not sure I agree that service conductors have been run with non-service conductors, but it's either that or the grounded service conductor has not been brought to the service disconnecting means as required by 250.24(C) (item 2). It depends on whether you regard that neutral brought to the new panel as the feeder neutral or the service neutral. Whichever it is, the other is missing.