Hi,
Are you trying to make a Maximum Power Point Tracking MPPT charger?
You cannot regard a PV as a voltage source like a battery, it is a current source and behaves completely differently.
Can you tell us what you want to control, the input voltage or the output voltage.
Thanks.. Tom.. 
PS. Forget about using that sort of CAD, the best CAD is an image of a hand drawn circuit.
Its faster and you don't have to try and draw fiddly zigzags and curlies with a mouse.
Please label pins as well, especially the MOSFET and put its part number on the diagram.