Good question, will the panel be in a location where it will get full sun? Will the day be sunny? (that is the hard part, I know, I have 6320 watts of solar, of that only 1480 is battery back up.) How much power does your pump use in watts? What type of charge controller is it, PWM or MPPT? The latter will get you the most power but it costs far more. How many AH deep cycle battery will you have.
Basically, you have a couple of options. The first is to have 2 such batteries, use one while you charge the second on house current. Another is to have a back up plan to charge the battery if there is not enough sun. Remember, especially if you have just 1 battery that it will be drawing power all day and all night. In the daytime whatever the solar generates, first goes to run the pump, only the excess goes to charge the battery. Many producers on this site use 12V deep cycle batteries to run a pump but I'm not aware of any that use a 250 watt solar panel and CC to maintain the battery.
If your charge controller (CC) was 100% efficient, which it is not, a 250 watt panel in full sun under test conditions will generate 250 watts per hour. On my 1480 watt system I have very rarely seen even a brief moment where I got 1480 watts coming in. The few that came close or even exceeded the 1480 watts were when the temperature was quite cold (the panel will generate more power at -20F than at +40F in full sun). However I'll guess that on the good days (sun wise) you should be ok, on a rainy day you will still run for 24 hrs but won't have enough energy left to get you thru the second night. Give me the pump, battery and the CC specs and I'll try to get more specific.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.