No, you have no panel protection diode. there must be a diode right after the panel, before the point C. It is essential.
If the sun goes down and you have no load at the moment, the input capacitor will return current which can destroy the junctions in the panel.
Diode D1 protect only the buck from the battery. Also the input capacitor is good to be bigger. At least 2200uF in my opinion.
Plus ~1uH inductance after the diode - will help a lot against noise. Few turns on the fly.
SDR sounds interesting, it is something new for me.