PV can be competitive with other sources in terms of generation costs during daily peaks, just when it gives most (the market effect currently observed in Germany), but good point about saving the distribution charge with self-consumption. On one hand, self-consumption can be enhanced by focusing on rooftop solar (both rsidential and industrial), though the Japanese feed-in law doesn't focus on that. On the other hand, if surplus cannot be fed into the grid, then generated electricity will be wasted or needs storage, and in both cases real generation costs will increase, so grid connection is a key. I have nothing against solar streetlights, but they are beans compared to total consumption, hardly something to be the main focus.

_{*Lunatic*, n.
One whose delusions are out of fashion.}