Fragility, in Taleb's sense of the word. And money.

If you're still grid-connected, you're still paying "service charges", a majority of the cost of electricity here.

And whilst notionally you can get paid for feed-in to the grid, in practice its a govt-regulated oligopsony. Here, feed-in tariffs were recently lowered by decree to 1c per kW/h.

A majority of solar systems here are "grid-tied", so if the grid goes out, you go out. I've never seen a transfer switch in this country, I should check the AU Standard but I believe they're as good as illegal, even though very common in Asia.

Off-grid is simply better.

If you're worried about hail, screen with pvc-coated wire mesh. You'll lose maybe 5% peak. Or do what I do and keep spare panels behind the shed.