We too added solar panels to the roof potentially saving about 12% of our energy use for common areas. Beauty of this project is :
No penetration of roof waterproof membrane as installer used Schletter clip / unclip system where the panels are clipped to an aluminium frame which itself sits on a few strategically placed hard rubberised tiles ( so no penetration of roof waterproof membrane and free flow of rain water under the panels to the drains ) and the panels withstand gusty winds by strategic placement of specialised concrete bricks ( they call it “mounted ballasts” ) behind on the aluminium frames after determining their angle and number after using GPS tracking technology from Schletter German HQ. Recent gusty winds in Sydney did not move a single brick or frame.