Personally I think it's a great Idea, it will be far easier to service the panels that are on the ground and your solar panel "field" could be easily expanded to accommodate more panels than you could possiblity put on your roof. So long as the panel field isn't too far away from the house, the voltage drop shouldn't be significant, but perhaps you should run heavier guage wire to the panel field than required to support additional panels and to protect against voltage drop.

The only thing that would concern me would be security. Copper thieves are ripping piping out anything they can get there hands on. While the black market for Solar panels isn't exactly matured yet, believe me as it catches on more in the future there will be more enough people looking to cash in on expensive solar panels. You might want to consider planting small trees around it (but not high or close enough to shade them) to shield it's visiblilty from the road.