The answer cannot comprehend all cases; your technician will know where to face it and how many degrees it has to be raised in order to work correctly “in your area”. From a personal interest point of view, the panel has to face the sun in the position this has at 12:00 midday.

The sun should hit the panel at a 90 degrees angle; to achieve this, the panel need to be elevated from a horizontal position of a certain amount of degrees depending on the latitude of your home and on the season you want to give priority (since the sun changes elevation every day).

The further North or South you go, the higher the panel needs to be. Should you live at 40° either North or South, the panel should be elevated 33° from horizontal facing either South or North respectively. As a general rule, solar thermal panels are raised from a horizontal position of an amount of degrees equal to the latitude plus 10.