Putting Solar Panels in England or Seattle is basically worthless. In extremely high clearness Ratio areas (El Paso, Phoenix, San Diego, etc) putting them on buildings is fine. But like wind, it best to put things where the resource is.
A few years ago, I calculated how many panels we'd need to power ourselves with Solar Panels, if we wrapped them around the earth at the Equator. It was about 200-250 miles wide. But you're right, it doesn't take into account the transmission losses.
One thought has been that instead of using the solar power directly, you use it to create a transportable fuel. Hydrogen is always the one discussed, but I don't want to open THAT can of worms here.
Seriously, it is RAINING energy, but we don't really have the right bucket to capture it.
Panels need to drop in price to about 1/4 of what they are to make them commercially viable in this part of Texas.
Here are the maps:
