Let say S is the balanced point so current flowing through galvanometer is zero. This is because the potential difference across PS is the same as potential difference across solar cell so no potential difference means no current flowing.
1) If I want to compare the potential at a point, is it correct to say V at P = V at A and V at S = V at B?
2) There is potential difference between point A and B (which is the same as the emf of solar cell) so why no current flows from B to A or A to B?
3) If point S is moved to the right (towards Q), then potential difference across PS > emf of solar cell then current will flow through galvanometer. How to determine whether the current will flow from A to B or B to A? And I think PS and AB are parallel and in parallel connection the potential difference will be the same but VPS ≠ VAB, what am I missing here?