Yes, the distance could kill all hopes of making the system work for both the pump and the house, but if the system was designed and installed to serve the pump needs, then there may be other limiting factors also.
Was your designer competent? if so, then he likely knows all the variables, and you might get a better
answer if you simply asked him the question directly. I think Most system designers would be willing to explain those things to the home owner.
Maybe the right question to ask him would be something to the effect of "If I wanted to use excess energy from these panels at my house, what would I need, and what would it cost." Contractors are happy (usually) to talk about more work. Then you could post what he thinks the considerations would be and we could have a better idea of whether it seems like he's really on the ball or just giving you a run around.