Does anyone know if the lighter socket is wired directly to the fusebox?

I know the lighter socket is only powered when the ignition is on, but I need to add a reverse diode to bypass this so that I can add a solar panel to re-charge the battery when the car is sitting in the driveway (i.e. the power will be going into the battery instead of away from it).

The best place to do this would be in the back of the main fuse box but I dont know if the power goes Battery--Ignition--Regulator--Fuse--Socket.