Plus those installations can provide a shedload of REACTIVE power, very, very useful for grid stabilization.
They can, but are they? I have only seen residential solar which reacted to grid overload/underload situations (i.e. situations which should never occur in an ideal world), not any which reacted to constant requirements for reactive power. Do you know of any which take part in the standard grid stabilization in normal use, outside of grid emergencies?