I have to bite my tongue every time this question comes up. Things just don't add up. First, the efficiency of the panel (any panel) will be < 40% with all things that effect efficiency at the max like pointing direction, tracking the sun, clarity of the panel glass, heat sinking, etc, etc, etc. Second, the output of the pump is only about 2GPM which is OK if you are filling a water container for your cattle and you've got all day (full sun) to do it. Third, you should probably consider using two 12V batteries as a backup because you will not be able to get significant amounts of water during the peak solar day to do you any good. In other words you will most likely use your solar panel to charge your batteries rather than operating the pump. (Run the pump at night off the batteries and charge the batteries off the solar panel during the day. Even then you should use a timer so that the batteries don't run completely down) Last, high efficient solar panels are very expensive so I doubt you will be getting the latest design, high efficiency panels for the price listed in your link.
Good luck and welcome to CT
