A few comments on panel size:

As Carl points out, if you only need a few degrees heat rise, then you probably don't need many panels.

However, the more panels you get, the faster the pool will heat and the higher the temp difference.

One advantage of a large solar panel is that it can extend your swim season if that is something you are looking for.

This is why I went with 85% area coverage. This year it really paid off. We had a few warm days in March and I was able to bring the water temp up very quickly to the high 80's. With a solar cover, I have been able to maintain 85-90 since then so when the air temp is warm we can swim right away instead of having to wait several days for the water to warm up.

I can get over 15 degrees of heat gain with my panels and I have easily extended our swim season a couple of months on each end. This is useful for where I live but may not be so important where you are.

So it really is all about what you are looking for in performance.

As for pump head, most in-ground pool pumps can easily handle solar panels even if they are on the roof. On the roof, the pump will temporarily experience static head which is the water lift to the top of the panels during the priming phase. So if the upper most part of the panel is 25 ft high, that is 25 ft of static head. After the panels are primed, the water falling on the other side cancels this out so you are left with only the dynamic head increase which is usually much less than 8 PSI (20 ft of head increase).

A decent rule of thumb is that the pump should be handle twice the height of the panel so the priming is fast and the vacuum release valve is closed quickly. For a 25 ft. high panel, at most only 50 ft of maximum head is need. Nearly all inground pumps provide this.