There are four basic types of solar panel mounting structures, each with their own pros and cons:
Roof mounts typically keep the wire run distances between the solar array and battery bank or grid-tie inverter to a minimum, which is good. But they may also require roof penetrations in multiple locations, and they require an expensive ground fault protection device to satisfy article 690-5 of the National Electrical Code-NEC.
Top-of-pole mounts are relatively easy to install (you sink a 2-6 inch diameter Schedule 40 steel pole up to 4-6 feet in the ground with concrete). Make sure that the pole is plumb and mount the solar modules and rack on top of the pole. Top-of-pole mounts reduce the risk of theft/vandalism (as compared to a ground mount). They are also a better choice for cold climates because snow slides off easily.
Side-of-pole-mounts are easy to install, but are typically used for small numbers of solar modules (usually no more than 4 modules), i.e. for remote lighting where there already is an existing pole to attach them to.
Ground mounts are great when you have a good amount of land – you can face the panels more easily in the direction of the sun, in case your house/roof isn’t perfectly south facing. And you don’t have to mess with the roof on your house. These ground mount solar arrays, however, require fairly precise foundation setup, are more susceptible to theft/vandalism and can have excessive snow accumulation at the bottom of the array.