But what you are doing is adding the PV as if it is a load, limiting it by combining it with the other loads not exceeding the bus capacity. Not even looking at actual loads but each breaker capacity.
705.12(B)(3)
(3) The sum of the ampere ratings of all overcurrent devices on panelboards, both load and supply devices, excluding the rating of the overcurrent device protecting the busbar, shall not exceed the ampacity of the busbar. The rating of the overcurrent device protecting the busbar shall not exceed the rating of the busbar. Permanent warning labels shall be applied to distribution equipment displaying the following or equivalent wording
Even using this method you will not get a net metering in excess of usage for POCO to owe customer.