Does the Smart weather sensor have to be aligned exactly towards the south?

No, the Smart weather sensor does not need to be precisely aligned. The position of the sun (direction and height) is calculated exactly. The Smart weather sensor knows the date and the exact time through the built-in DCF receiver or through the time of the Premium gateway. In addition, the geographical position is transmitted to the Smart weather sensor once by the gateway, and the position is calculated from this information.
The Smart weather sensor should nevertheless point approximately in the direction of the south, as otherwise the housing may cause unwanted shadows.