My super pump is 2 speed and I run it at low 95-99% of the time--with solar panels. But my pump is close to the pool, and the panels are the deck around the pool (nice! The deck stays cool to walk on !)

I don't know all the math but I suspect a 2.5hp pump is too darn big for most pools--but the spas may need it.

With 26k, you can go with a 1.5 superpump 2 speed and STILL get great performance in low speed.