[rcxdude]

It's somewhere in-between: residential solar, when feeding back into the grid, is only using a small fraction of the transmission compared to a commercial solar plant (in terms of length of wiring and number of transformers used to transmit a given amount of power). In fact, it will generally be (unless in a neighbourhood where nearly every house has solar installed) reducing the overall load on the grid. So it's not reasonable to expect that the value of that electricity is the same as that of the same amount coming from a large utility, but it's still probably not worth retail prices, either (though maybe it is, in certain circumstances. In cases with a very overloaded grid it may conceivably be worth more!)

[s1artibartfast]

the grid is a fixed cost, which is needed unless we are willing go without power every night and winter. Once it is in place, it costs the same if it is sitting idle or being used.

There are absolutely no savings from an unreliable local power source.