Okay,

I've been studying some of the Heat Output vs. Temperature curves for various heat pump manufacturers, and I've come up with a rough estimate that heat pumps will be about 25% less efficient in my area due to lower humidity and the lower average operating temp compared to published COP values. So yes, everyone here is right, heat pumps will definitely work and heat my pool in my area.

However, with my current local energy rates, calculation of energy costs for my specific situation shows that a heat pump with a COP of 4.3 produces heat at an equivalent cost of a 95% efficient gas heater (Again, specific to my situation only). Any heat pump with a COP of greater than 4.3 will start to show energy savings compared to gas. Since most heat pumps are in the COP range of 5-7, yes a heat pump does make sense compared to NG heater.

However, once I started to make calculations for solar, the cost calculations seem to skew in favor of solar. The problem with solar is that it will provide a fairly limited amount of heat, and cannot increase it's heat production based on demand. Also, it won't heat my spa, so I'll have to include the cost of a small gas heater anyway. I'm building a spreadsheet to help with my cost analysis, so maybe someone can help me with one of my variables that I can't seem to get a handle on.

I need to know how much heat it will take to maintain a temperature for my pool throughout the pool season.

So say for example, my pool is going to be 650 Sq Ft., 24k gallons, and I want to maintain a temp of 82deg.

Say it is 25% shaded, and I will not be using a pool cover. If the pool season will be from the beginning of April to the end of Oct (6 months), how do I determine how much heat (BTU's or therms) I will require for the entire season?

Without this critically important piece of information, it's kind of to make an informed decision. Can someone please help me with this variable?