I am in charge of an indoor public swimming pool. Its size is 50m x 25m and every month approximately 3500 swimmers use it from 07:30 to 22:00 daily. For now only oil is used for heating the pool and for the other water uses (shower etc.). I am looking for a different way of efficient heating the water using the sun to save on our energy costs. Please give me information about this. Thank you in advance for your tips and advice.