I dont think you want water in plastic sitting in your attic..The idea of solar mean you need direct sunlight ...If you want a good pool heater then get an AquaCal heat pump w/ titanium heat exchnger......They are the best...... I had one put in when I had my pool installed. My pool dealer never heard of Aquacal until i asked for it. Now they sell more of them than any other heater. Couple that with a good solar cover and you'll be quite happy....Just make sure you prtect your solar cover when its on the reel, get the cover for the solar cover or it will fall apart in a year or two.