How to determine the Solar-panel power requirement battery
First you need to know the amount of daily working hours of the motor. 
How many days do you plan to run it without sun ( cloudy days)?
Even deep cicle batteries suffer from deep discharge. Put in your calculations that you shouldn't discharge frequently the battery, no more than 30% ( for depp c. battery)
THe solar panel should be able to charge the battery on sunny days.
So make the calculations for the solar panel depending where you live.
Use this for the calculations.
http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php#