[secabeen]

Eliminating the delivery of kWs doesn't change the grid costs one whit. Grid costs are driven mostly by the number of customers, the max demand that the grid has to support at one time, maintenance, and the distance the lines have to travel to reach you. Just like a water main or sewage pipe, reductions in demand only change the cost of distribution when they are large enough and prolonged enough to allow for smaller equipment and fewer lines.

Having a residential power connection from the grid allows you to demand up to 200Amps of power, at any time of day or night, 365 days a year, with zero notice. The power company has to build the lines to support that potential demand, whether you use it or not. Over all of California, distributed solar probably has reduced the expenditures we would have need to have made on new transmission and generation facilities compared to a world without distributed solar, but that doesn't affect the baseline cost of a ubiquitous grid that serves from Crescent City to the border with Arizona at Yuma, and all points between.