your own third scenario analysis shows (grid power $0.1/Wh), if all rooftop options are cheaper than grid, a worse $/KWh would be chosen as long as it saved rel

your own third scenario analysis shows (grid power $0.1/Wh), if all rooftop options are cheaper than grid, a worse $/KWh would be chosen as long as it saved reliance on the grid. You left something out of your analysis: people can have an ethical reason to assign a cost of $0.1/Wh to grid power, because they consider environmental externalities they're not paying for, to be something they actually are paying for. If forced to, they may use the grid, but they might treat its cost higher than the listed cost. You've summarized things well in your second sentence: "In any system analysis, you have to consider all the relevant factors." As both your and my analysis show, it is not simply the dollar per kilowatt-hour that informs purchase decisions. If a certain cheap solar array manufacturing process was extremely toxic to the environment, the environmentalist might not buy it at any price. it's a complicated, not simple analysis.