I have a solar batch water tank that supplies my garden shower that I am Very Happy with. I'm kicking around putting together a panel air heater, or 2, to heat my shop. This will have a PV cell to power the small fan that will circulate the air. I'm no design/tech wizard but would think it would be an easier/cheaper/smaller project to put together an 'air panel' Go back over past postings, there are a number of links/pics that will have you laying awake at night, thinking. Good Luck.