The solution here seems to create a zone that is completely inhospitable to the ecosystem that should exist in that spot. In the picture in the article, the bird poop will be highly concentrated in the forest area that is nearby. While there will be some birds that fly over this dead zone, I bet the droppings will be minimal.
Edit: The article mentions a 100 MW installation. At 2.5 acres per MW, that is 40 acres or 0.25 miles x 0.25 miles. While there will certainly be some service roads, no matter what the ecosystem was before, it will be covered with something that doesn't support plant material, insects, etc. that may be consumed directly by birds or the small animals upon which birds prey. Birds will find a more hospitable place to poop.
Edit: The article mentions a 100 MW installation. At 2.5 acres per MW, that is 40 acres or 0.25 miles x 0.25 miles. While there will certainly be some service roads, no matter what the ecosystem was before, it will be covered with something that doesn't support plant material, insects, etc. that may be consumed directly by birds or the small animals upon which birds prey. Birds will find a more hospitable place to poop.