“There are two principles that govern the orientation of tennis courts. These are:
– The position of the sun.
– The effects of shadows cast onto the court surface.
It is important to avoid players having to look into the sun when facing the opposite end of the court. As the sun moves from east to west during the day, then a similar orientation of the tennis court must be avoided. The effects of the sun are minimised by adopting a generally north-south orientation, such that the sun is to the side of (or directly overhead) the court. The general principle to follow is that, during times of maximum usage, low elevations of the sun should be avoided behind the server (it should be noted that the sun is at its lowest elevations early and late in the day).”
Source: ITF Tennis