Here in the desert, covering the pool or uncovering the pool would make a major difference when heating it up. Swamp cooler effect is major here. My solar cover is about toast after only two seasons, but I refuse to buy one until next year. I probably lost 2 weeks of swim time by only partially covering the pool. It's kinda crazy. I have no heater so it's over for 2021.. we are down to 72F now...I'd say the best it could do is calculate how much energy a gas or heat pump run would use but it would only give a very rough estimate of temperature rise because there are many other factors that dictate pool water temperature that would vary greatly between pool types and ambient atmospheric conditions. Might be ok to add the the "Effects" section. Later on, with addition of automation tracking, it could be added to the list of Log items
I don't know how you'd accurately would calculate that out without more inputs than you'd want to enter on a phone app.