It is basically is latitude of Pakistan and it has been calculated that latitude of a place is the angle that gives optimum output for solar panels.
When tilt angle is 2° , area under the graph (green line) is lowest as compare to other tilts but we can attain maximum output in summers. Area under the graph represents the output power through out the year more the area under the graph more the output power.
When tilt angle is 45° area under the graph (green line) is better as compare to 2° but its is not optimum and gives good output from module in winter only.
When tilt angle is 30° area under the graph (green line) is optimum (max) and we can achieve optimum output in both seasons as graph shows.
For more information visit this website: https://www.pveducation.org/pvcdrom/properties-of-sunlight/solar-radiation-on-a-tilted-surface