A MOSFET is not going to work as it conducts in both directions when 'on'.
Ideal diode circuit of a MOSFET wires the MOSFET such that the body diode direction matches the desired current direction. Then a control circuit monitors the voltage across the MOSFET to emulate a diode, somehow measuring the current to keep the MOSFET on (bypassing the Vf=0.7V body diode) during forward current, but quickly turn the MOSFET off if the direction of current changes - just like a diode would do. Most obvious way to measure the direction of current is to measure Vds - to maintain a small voltage drop over the MOSFET - just like a diode has Vf. The more accurate the control circuit is, the lower this drop can be, but drop is still needed.
So now we have a complex, more expensive MOSFET circuit, which needs external supply voltage, and which
still has Vf drop - maybe just 0.1V instead of 0.3V that of a schottky diode.
This drive complexity, requirement of external power supply, and minuscule gain to be had, are the reasons why this is not being done on solar panels.