Cost bado utalipa. The pump won't run all the time because the sun isn't up all day. You'll need a big battery and all associated electronics to store all the energy. You could also buy a tank and then pump all the water into the tank during the night and release it on demand which in my opinion is the safest option.
The pump to do this doesn't necessarily have to be a solar pump, could be diesel or just a simple induction motor. Now you need to sit down and calculate the cost of all these expenses and choose which one is cheapest.