No, the environmental sensor does not need to be precisely aligned. The position of the sun (direction and height) is calculated exactly. The environmental sensor knows the date and the exact time through the built-in DCF radio receiver or through the time of the HomePilot. In addition, the geographic position is transmitted once to the environmental sensor by the HomePilot, and the position is calculated from this information.
The environmental sensor should nevertheless point approximately in the direction of the south, because otherwise it can happen that the housing leads to an unwanted shadow formation, if the sun is in the east in the morning or in the west in the evening.