So, you put all that high voltage electricity generated by those solar cells on the fence. You will still have to use conventionally generated electricity to electrify the fence at night because solar works only during daylight hours.
Finally, the electric fence idea is a short circuit to failure. And the higher the voltage on that fence, the bigger the blowout when that ground clamp is applied. It should take out at least a few transformers in the string.
A better way is the use of Predator Drones outfitted with Small Tactical Munitions to kill border crossers. Of course, what kind of reaction you would create with that type of action is anyone's guess. A few dead children, old women, little girls, who knows, you might risk starting a war with Mexico and perhaps retaliatory terrorist activity.
They work great!!!!
BTW, there is NO RISK OF WAR WITH MEXICO.