Here is what I did. I ran a Tee with a valve off the line that feeds my returns, they have valves in-line down stream of this. I hooked up two 2' by 20' solar mats which I got on eBay for aout $175. I have an Intelliflow variable speed pump. During the day I valve out the returns and open this line and run the pump at about 1100 RPM. I get plenty of flow through the mats and the pump uses about 100 watts of power. At night I run the pump at a high flow rate through the main lines. This works double well since I have time of day power pricing and it much cheaper to run at night. I have a 20x40 IG pool and these two panels plus the solar cover are enough that the pool stays between 80-85 degrees except in April and Sept when I need to run my heat pump a little.