Hi iw,
I'll be glad to do this Had no such fun from long time.
I need the nominal voltage and maximum current values of the panel or just the model.
I noticed the lack of general decoupling diode in your circuit. Is needed for reverse current protection. May be the panel have such internally.
Also a small input filter will be good idea, because the input current of the buck is trapezoidal and is very stressful for the panel.
So the preferred converters are boost (when is possible) or sepic. The input currents there are triangle in continuous mode.
I allowed myself to check your CQ on the net. How far you've come with SG3525 inverter ? I guess it will work with this converter .... ?

Regards