Why tilt equals latitude
A panel produces most when sunlight strikes it square-on. Averaged over the year, the sun's path sits at an angle set by your latitude — so a fixed mount tilted near your latitude collects the most annual energy.
True vs magnetic direction
Phone compasses point to magnetic poles, which differ from true poles by your local magnetic declination (2–4° in Pakistan, more elsewhere). Correct for it during installation, or your "south" may quietly cost you output.
Which direction should solar panels face?
True south in the northern hemisphere, true north in the southern. Up to 10–15° of east/west deviation costs little; facing the wrong hemisphere can cost 15–25% of annual output.
What tilt angle is best year-round?
Approximately your latitude. Karachi at ~25° latitude performs best near 25° tilt on a fixed structure.
Is seasonal tilt adjustment worth it?
Adjusting twice a year (latitude −15° in summer, +15° in winter) typically adds 3–5% annual yield — worthwhile only if your mounting makes it easy and safe.