Khách sạn bãi biển tại Wannsee,

"The hotel is the top floor of light rail train station “Wannsee” hence is very well connected to the lake as well as to the railway downtown. Don’t expect a luxurious room but it’s clean and very reasonably priced, especially for Berlin. Parking is free between 18:00 and 9:00, otherwise free for an hour with a “Parkscheibe” (the blue thingy that should be in your car), but the spots are scarce. However with luck and good timing you can get a spot, especially in the evening. No breakfast, but...