Cross one off the to-do list
Edit: Looks like my earlier post didn't make it here... So here goes again...
I don't think the setup in your schematic will work very well since there is nothing keeping the PV cell from being pulled to very low voltage (making it produce very little power).
Unfortunately you cannot just hookup the feedback of the controller to the PV side to regulate the PV voltage since the circuits for input vs output feedback regulation work backwards, ie:
For input feedback, you want to pull less current when the voltage drops.
For output feedback, you want to pull more current when the voltage drops.
If you use a chip that gives you full access to the error amplifiers, you can setup the feedback to work whatever way you like, including a proper input feedback. Unforunately, most companies don't make such chips and the only ones I can think of off the top of my head are the super-old and inefficient TL594's (
https://focus.ti.com/docs/prod/folders/print/tl594.html).
Alternatively, you can use a setup like a transistor inverter to invert the feedback chain of the controller.
Well, I did what I suggested earlier. Attached is a spice shot and source for LTSpice. You'll have to change things around a bit if you actually want to build something, but I think it's good enough for a proof of concept.