Scottg - unless you know the loss specification, of the feeder at Orford, YOUR calculation is meaningless rubbish.
Clue, the Co-ax used is as thick as a large drain-pipe, designed to take 600kw of RF power.
The loss in fact, is VERY low.

The only real limiting power factor, will be OFCOM, & finance - remember, the Solar cells only work in daylight.