I would strongly recommend getting a grid-tie system. You may want to consider contacting a local solar installer who can guide you through the process. Generally, to connect to the grid, you're going to have to have the system professionally installed and inspected (you MUST have it professionally installed if you want the tax rebates).
Also, you should stay away from string inverters and go with micro-inverters (one inverter per panel). Micro-inverters give you a lot more flexibility in building the array and dealing with shading and/or growing the array.
Make the grid big enough and you can not only run your pump, but your whole house. My array is 5.62kW and, as of this writing, it is generating 4.71kW (the house normally consumes about 1-1.2kW at any given moment).
For the month of March, I produced 715kWh. That's not too shabby. And the tax rebate money is rolling in now.
See my other thread on the topic if you want more details about my array.
i could not find a switch ( assuming that is what it would be ).
They are called ATS (automatic transfer switch). The obvious thing to look for is a model that can handle the load of the motor (including startup currents) and that allows to give priority to one of the inputs (in your case the solar panel).
Less obvious but just as important are: - sensitivity for detecting good/clean power (some ATS may not like inverter output power and therefore often or permanently switch to the utility grid). - constraints on failover switching: the ATS I have at work will only failover if at the time of the power failure frequency and phase of the two power sources are identical (when phase or frequency drifts the failover is disabled). Such a restriction would not work for your scenario.
I agree with ke4pym that a grid-tie solar panel may be the better option for you (unless utility power is very unreliable). -- Got some spare cpu cycles ? Join Team Helix or Team Starfire!
grid is reliable, just wanted to see if i could do it. i have been playing around with a few micro solar pumps and some plug and play solar lights. -- ummh union bad, ummh union bad, please tell me what else to regurgitate
A grid-tie system would be the most logical thing to do.
Even when the solar panels don't put out enough power to run the pool pump, they can still feed a few hundred watts back into the grid and offset some of your electricity costs, instead of sitting there doing absolutely nothing.
Also, if you run the pool pump at full speed 24/7, maybe consider running it on a timer instead for additional energy savings. It does not need to be running all the time.