Power switch between two sources using mosfets
Well I finished it, basically I had to switch the source instead of the drain using comparators to prevent the transistors of acting like resistors and draining power. For those interested here falstad simulation the actual circuitry what we choose/created is placed.

It basically switches either one of them (by means of a comparator, op amp in circuit, - I simply forgot active items when placing this question). It switches based on some reference values. Experience in practical comparators dictated now that the source for the comparator always should have a higher voltage than both inputs - thus the inputs should simply be halved. Also from experience we had to add a "pull up" resistor. But other than that the circuit worked.

The digital schematics are there to provide hysteresis as the solar cell array can only provide power for half the time (values of current source &amp; capacitor bank are adapted to be able to simulate without waiting hours).