Before you begin, consider your climate and reduce your expectations.Nighttime temperatures tend to undo daytime gains, even during sunny weather. A pool blanket is absolutely essential at night as this is when the majority of heat loss takes place – when the air temperature is much cooler than the water. An in ground pool will lose heat faster than an above ground pool as the ground area below 3′ in most areas is cold even during the summer. Do you have space for solar panels to receive direct sun most of the day? Will you remove the panels prior to high wind storms and perhaps each winter? Will the reduced water flow still clean your pool or is running your pump for more hours acceptable? That said, the low cost and ease of installing your first panels may make it feasible for you to experiment. In most situations plastic solar panels will increase your comfort during the regular swimming season however they are not likely to increase the length of the swimming season unless you supplement with gas heating also. No prior planning can substitute for the experience of trying it out.