When you look around and see solar installations there are three preferred installation styles, roof, pole and ground. Traditionally solar panels were put on the roof of a house or building. Then pole installations became very popular. This is where the solar panels are mounted on a rack that is attached to a pole that is anchored into the ground. Then recently with the rising number of solar fields (or huge empty lots filled with panels) has come the use of ground installations.
Typically you will not see a ground installation in a small installation, these are used in large installations where even though it may not matter if they are not the most efficient but the ease of installation and maintenance is key.
With the rise in building codes for solar installations and as solar installers get more experience they are trying to shy away from roof installations. This is for a very simple set of reasons. Most roofs do not face the best direction for solar gain. If you mess up on the mounts to the roof you could cause leaks and be financially responsible for any water damage to the home, and it is not the safest place to be carrying around large flat panels that wind can catch.
In residential and many commercial installations the pole installation is become the favored style. All that is required is that you have enough ground space to anchor a pole into the ground. then enough clearance around the rack so it can gather solar energy.
Some of the pole mount racks are called trackers, they do just that, by some way they move with the movement of the sun to ensure optimal sun energy all day long. However this can be dangerous in larger installations because of wind it is safer to install a solid rack that does not move.
Now in Mexico the story is much different than in the US. Since there are little to no building codes roofs are favored. This is true in many non developed countries, the roof is the easiest and cheapest option for the solar panels. So they will be mounted to the roof in the easiest way possible. Often it will not even include not even putting in a angled rack. it will just be flat mounted to the roof.
I have worked on all of these installations and I have to say that the pole installation is so simple and has so many advantages the extra cost is very much worth it. They are easier to access and easier to keep away from shade of trees and buildings. But if not done right in a high wind area they can cause more damage than a roof installation.
