8) i had built one using two mosfets connected in common source configaration, both source are connected and both gates are connected.
the switch turns on when you apply a voltage from gate to source
ANY MOSFET WITH RATING MORE THEN PEAK LINE VOLTAGE CAN BE USED IN IRF CKT.YOU MUST USE PHOTOVOLTAIC ARRAY.
OTHER THEN PVI 1050 THERE IS CT202D FROM SEMITRONICS.