Most people think that the sun always shines. What some don't realise is that they sleep away the dark hours of the night. If they stared out the window all night, as they do in the daytime, they would soon realise the correct ratio of sunshine and darkness.   The main problem with solar heat is that when the sun is hottest in the middle of the day, no one needs the hot water. Hot water is needed between 6pm and 9pm in the evening and after that there is no more sun to heat the water for the next morning. Now the first thing that pops into mind would be to install a much larger storage tank so that you don’t deplete all the water during the evening and still have some for the next morning. Now by doing this you are not installing a standard solar system and by installing larger storage, more solar collectors will be required on the roof.