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Of course domestic PV are connected to the grid shitfer. How else can power be exported? One reason they are disconnected on power failure/outage to prevent them feeding back into the grid and electrocuting whoever is making the repair.
BTW, the ones on poles are not "obviously connected to the grid" I can think of several reason why this might nor be so. All of them to do with money.
Micro-power generation is beneficial because it can be connected to the grid without needing to enlarge/modify the grid, the power generated is used locally. Also it is more secure, if one generator goes down,it's neither here nor there.