And 70 degrees is 20 degrees away from vertical 90 degrees so the lower efficiency by having a flat panel vs. angled is 94% so isn't that much (i.e. just a 6% loss in efficiency). Like I said, I think this "angling" difference will only be an issue for you if you live way, way north in Canada, but at least now you have the tools to know for sure.

As Carl says, the angle of the sun at noontime depends on the time of year. The main reason to have the panels angled isn't so much for the summer solstice time as it is for the beginning and end of the swim season when you more desperately need and want solar heating of the pool. At such times of the year (spring and fall) the sun is lower in the sky (at noontime). Those that live at the equator don't worry so much about these problems, but I suppose they've got other things to worry about!

Richard