[samhass]

You can't possibly pay for the whole system in months. I leave my gas heater on year round and keep the pool around 90 degrees. The worst bill I ever had was the first month. That was around 500.00. Other winter months of very cold weather run around 300. per month. If I took my entire gas bill for the year and attributed it to the pool, it still wouldn't pay for itself in a year. It will take me a minimum of three years for the payback and I'll be happy with a 3 year payback and knowing that I'm being greener. My pool is an odd shape and holds around 8400 gallons of water. Take into account that I will still have to augment the solar with gas in the colder months of Dec-Mar.