In order to fit thicker 3 8 bolts into the 1 4 holes on the hightec solar panel we drilled out the hole with a 3 8 bit.
Fitting solar panels to roof rack.
I live the van life full time out.
The solar panel mounts are bolted onto the rack so we can swap in new brackets if we want to upgrade our panels or remove them completely and have a cargo rack.
Your installer would temporarily remove the tiles install the hooks underneath into the roof then put the tile back over the mount and rack the system from there.
The second option is called a comp out where your installer will remove the tiles where you intend to put solar then lay down composite shingle to install the array.
To secure the solar panels to the unistrut crossbars we used 3 8 bolts external tooth lock washers and nylon unistrut cone nuts.