Electricity transmission is constrained by line loss, which is proportionate to amperage. To minimize it, voltage is raised to as much as over a million volts, keeping amperage down. This makes for very serious cross-country transmission lines, and electric companies still lose a quarter of the generated power to it. In my opinion, the two great strengths of solar are cleaner power and localizing power generating with its use.
Proportional to the square of current (amperage). Or alternatively, inversely proportional to the square of voltage.
Unless you user superconductors, like cooled aluminium (if I remember correctly). There is a lot of research in this area at the moment. If you cool a conductor low enough, the resistance reduces dramatically and you can transmit electricity with very little line loss.
The problem is that it costs lots of energy to cool things so it's difficult to end up ahead unless we make dramatic advances in high temperature superconductors.