On a new main 3 wire panel where do I connect green from MC lite(BX) wires?
Since this is an upgrade of the service panel the grounding and grounded conductors really don't matter the side they are on. Both neutral and grounds can be on the same buss. If it is a sub panel the neutral and ground need to be isolated and the grounds on 1 side and the neutrals on the other to be code compliant.