Certainly the physical distribution of the radiation sources are important, but I didn't think that was worth mentioning in a simple summary comparison. Sieverts already attempt to correct for biological effects, but yes, if the radiation source is something that can internally bioaccumulate, it will have more complex and serious effects. That is beyond a simple single-measurement comparison, however.
the worst location in the continental U.S. is only a factor of two worse than the best solar location.
Solar is dead. Most of the US doesn't get enough sun to make solar feasible.
This article has a good solar efficiency study for the entire US. In summary, there's not a lot of difference in the contiguous US - about the only place where solar is significantly worse off is Alaska.
Although personally I do prefer "drone". It does afterall refer to "an unmanned aircraft or ship guided by remote control".
I have a number of pictures here (somewhat low quality), and several short videos from the same areas.