The wear on these components are based on usage, so should be rolled into whatever per kWh NEM rate they are going to propose. It doesn't make sense to pay for this as a fixed rate, especially not as an installed capacity rate (should be based on kWh input/output on the grid, as that is the actual wear, not the installed capacity, which is a number few people get close to generating even at ideal seasons). This is putting beside the point that solar users may reduce some of that wear by contributing to neighborhood energy demand, thus reducing the wear upstream.
This type of cost is what the minimum delivery charge is supposed to pay for, if it's not high enough, that should be raised (and should be raised for all rate payers, not just solar). But I highly doubt the $8/kW based on installed capacity is a fair rate for that, given that labor cost doesn't change based on installed capacity (it should be the same for everyone, regardless of solar capacity).