The Spar Valve is upstream of the engine. It is a DC motor Hot Battery Bus powered. The engine mounted EFSOV is fuel operated, solenoid controlled Battery Bus powered. That is as complicated as you want to make it, don't go into it any deeper than that. You will be vastly overqualified and not concentrating on the right stuff while you are learning to fly the plane, and not a bundle of laughs to fly with! The EFSOV is definitely Battery Bus powered. Beware using outside agencies for official Tech stuff. FCOM B Systems 12.20.2