If one part of installation is a little more prone to shading than the rest of it, does this 'drag the system down' if connected to single inverter? My friend has a typical 30's type property with a bay window and small apex roof bit above the bay that protrudes forward from the main roof. He has been told that shadow from this will effect panels mounted beside it and would therefore be better off with 2 inverters to seperate panels from main array further up roof to optimise performance. Given cost of inverters I would prefer to avoid buying 2 units, or was considering possible fitment of diodes to prevent back-flow to panels not pushing out voltage. Your opinions please.