There are many ways to mount solar panels. Every situation is different. There are flat roofs, sloped roofs of all degrees, pole mounts, trackers, and ground mounts. The latest solar in Europe is south facing walls or "facades". The facade solar panels are building integrated (BIPV) as are solar shingles or Sunslates™. BIPV means that you are dealing not only with a power producing solar product but also a building material such as a window, a shingle or a concrete siding material all of which happen to have solar laminated to or imbedded in.
Generally speaking, the solar panels are fastened together with aluminum rails then they are bolted to roofs or poles in order to get them secure in the south facing aspect where there is no shading during the major part of the day. Each system is unique to the site and the power needs. There is much engineering that goes on in the design process from roof load to pole size and depth to proper clamps, nuts and bolts.
The image above demonstrates the latest passive tracker. This is the most efficient way to install grid-tie solar because it earns extra sun credits in the summer months and is adjustable for winter. The tracker moves by the weight changes in heating and cooling freon with shadow plates. There are no motors using power to run the tracker. We have installed over eighty of these trackers and they work like a dream. However, due to the drop in the price of solar panels, the cost of tracking has become prohibitive making fixed mounts more cost effective.