It is important to ensure the succulent receives indirect sunlight. If the succulent is kept indoors, ensure that it receives adequate sunlight. The sap of the plant can cause skin irritation. Your succulent will turn yellow if it is overwatered or submerged. Too much water is the main reason why succulents turn yellow. Don't winter it during the afternoon because the scorching sun could deny the roots an opportunity to absorb as much water as possible. After repotting your Sempervivum, do not water it for several days. Before you repot it, let it dry completely.