solar users are using the grid, and are NOT independent of all the infrastructure. They are using existing power plants and transmission to provide electricity ON DEMAND.

Currently solar customers are being subsidized by non-solar customers for these costs (which are in the billions when you include original investment)

The charge is a demand charge, a charge to cover the costs to allow Solar customers to have electricity even when the sun does not shine. Too many people confuse fixed charges (ie power plants, transmission systems, and all the other infrastructure which allow customers to have electricity with the flip of a switch), with energy charges which are the actual kwh's that used.

Rate making allows an entity to receive both a return OF their original investment, and a return ON their investment. Otherwise utilities would never go into the business and never make the original investment