If you want to swim year round you need either a heat pump or gas. Heat pumps take time -- like several days and may still not be able to warm up a cold pool in the winter. They generally can't heat a spa. Solar will work in the spring summer and fall depending on number of panels, sunlight and orientation. Anything will require a good cover. If you don't have a cover you will end up heating your yard.
One variable is how hot do you want your pool. If you want to swim at 81 that is much easier to maintain (or achieve) than 91. 78 would be even less difficult.
A heat pump is better at maintaining a temperature than achieving one. So if you are going to turn thre heater on for a week then off for a week you should be thinking gas.
Generally most folks don't swim in their pools in the winter.
One variable is how hot do you want your pool. If you want to swim at 81 that is much easier to maintain (or achieve) than 91. 78 would be even less difficult.
A heat pump is better at maintaining a temperature than achieving one. So if you are going to turn thre heater on for a week then off for a week you should be thinking gas.
Generally most folks don't swim in their pools in the winter.