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.
Fixed ground mounts are similar in appearance, but they don't follow the sun through the day. A fixed mount is more efficient for an off-grid system in Montana as the money spent on the tracker could provide more panels toward winter energy support when you need it most.
Above is a balasted, flat roof system which allows for wind
sheer without making penetrations in the roof membrane.
Above is the rubber boot system which protects penetrations in roof
membrane but avoids the added weight of the balasted system.
By far the most common way to mount solar panels is with aluminum rails lagged to the roof. This is a metal roof with special clamps that fit the corrugations. There are special clamps for standing seam and most common are the asphalt shingle roofs. Cedar shakes don't accept solar mounting structures very readily.
Below is the mounting system for Sunslates™ which is usually done in co-ordination with the project carpenters. This cold roof design is used to ventilate the hot air away from the Sunslates™ so that they work at maximum efficiency.