It takes 30-40 minutes to bake sweet potatoes in an electric oven. Wash and dry the sweet potato first, preheat it in the oven 150℃ for 5 minutes, then spread a layer of tin foil in the oven, open the oven at about 200℃, put it in and bake it for 20 minutes, then turn it over and bake it again 10-20 minutes.