The performance of PV panels is affected by the shading effect of surrounding trees and buildings, passing clouds basically anything that casts a shadow on to the panels. The sun light converted into energy by the PV panels shall depend on the amount and duration of the shadow falling on it. Lesser the shadow, more the energy!
Solar panels need to face true south direction for maximum power generation. The reason behind it is that when sun moves from east to west, you get maximum exposure when you face southwards. Irrespective of which part of year it is, inclination will always be towards south. Hence for the optimum harnessing of sunlight, the solar PV panels should ideally face south.
The angle at which the solar panels are fixed is according to your location’s latitude. In general, the angle of tilt will lie between 9 to 12 degrees in southern part of India and 25 to 30 in north India. The angle decreases as the altitude of installation increases to nullify the impact of high speed winds on the installation.