I guess I was thinking of a much smaller motor being powered by the panels. If all I have to do is turn the water twice during the daylight hours, perhaps a very small pump/motor will do the job? At this point I am just speculating - hard facts must come next.

If you are thinking of a smaller motor, why not just have a smaller motor installed?

Still need the big motor if we run the spa or heat the pool. Might even need it to drive the pool vacuum for an hour or so.

A smaller motor may not use less energy. I know this sounds nuts but the issue with motors is the initial energy draw that they put on the system. The new variable speed pumps are also "soft start" motors. What this means is that the motor slowly ramps up instead of kicking on all at once. This capability really lowers the energy draw on the system.

Also, for the cost of solar it would be far more advantagous to use them to power the house if you keep the single speed pump. Again this is due to the large amp draw on motor start up. Go with a variable speed you will be far happier. Also, keep in mind that there is a trade off based on the pump curves that can allow you to run the pump over a longer period of time at a minimal head based on the electric rates.