Because there isn't really a good pie yet, they take far too long to pay off and can be dangerous to air traffic and wild life if they are A. in the wrong place, or B. installed incorrectly.
Oh, and if they don't have overspec'd components, they can cause a phenonom called "flicker" which is destructive of delicate electronics like your fridge, washing machine, A/C, and computer.
- Pilots have sunglasses.
- Wildlife have no problems with a flat piece of silicon that doesn't move. (Cars kill them by the millions though).
- And your electric circuit should have a fuse and other safety features that prevent fluctuations in the power.
How many of you trolls are volunteers, and how many are paid to troll by the coal/oil/gas lobbyists? This is just another scare tactic, just like everybody is now convinced that wind turbines kill birds, when in fact it is cats that kill birds.
Now move along, there is really nothing to see here.