takedownca, after you get on the roof, check if each panel has a little box (poweroptimizer) attached that has a serial number on it. This may help. My installer, a third party, made a map with the stickers from the poweroptimizer to create the layout. Unfortunately, I am still waiting for the power company to place the meters so I can operate. By Tuesday the 9th, everything should be operational so I will know more.