88045 Friedrichshafen: 570 apartments, 40,000 sqm living space, 4.2 million euros for solar technology = 5,500 euros additional investment per apartment = 83 euros/sqm living space, research project of ITW, Stuttgart, solar coverage ratio is of 50 % (heating and hot water), 4,056 sqm solar collectors, 12,000 cubic meters storage (33 m diameter, 20 m high)