Solar power systems are available in both ground and rooftop configurations, and each option has advantages and disadvantages. Note that the solar panels themselves do not change, and the main difference lies in how the racking system is mounted.
Ground-mounted solar systems tend to have lower installation costs, since there is no need to take all the system components to a rooftop. However, rooftop installations allow a more efficient use of land and are less likely to be shaded by surrounding objects.
Rooftop solar installations are normally used by homeowners and businesses, since they can be deployed on existing properties without using up additional ground space. Land is a very expensive asset in urban locations, and the installation savings of a ground-mounted solar array do not compensate the cost of the additional land required.
Even when the solar system owner has the funds to buy additional land, it will normally be used to build a larger house or to expand commercial spaces. If a solar array is being considered, it will end up as a rooftop installation anyway.
Rooftop PV systems also have a technical advantage over ground installations. Since they are mounted above a building, they are exposed to less shadows from surrounding objects – keep in mind that shading is among the most detrimental factors for productivity in solar systems. In a residential area, for example, a solar PV system on the ground is more likely to be shaded by trees around the property or by neighboring houses.
Another factor that favors rooftop installations is safety. Photovoltaic technology is environmentally friendly, but that does not mean it can be handled safely by anyone. The wiring and connections between solar panels and inverters should only be touched by trained personnel, and rooftop installations are less likely to be tampered with.
As previously mentioned, a solar power system has a lower installation cost when mounted on the ground. However, this approach is only viable if the project developer has access to large extensions of unused and affordable land.
Ground-mounted solar arrays are typically used by companies who are dedicated exclusively to power generation. Since selling electricity is their only commercial activity, they have little to gain by developing new constructions in the land intended for the photovoltaic system. Also keep in mind that these projects are normally located far from urban areas, where there is no market for commercial spaces.
Another advantage of ground installations is flexibility, since solar panels can be easily adjusted with the optimal tilt angle to maximise electricity output. On the other hand, rooftops often have fixed angles, and there is less freedom for solar panel orientation. Ground installations also offer better compatibility with solar trackers, since many rooftops do not have the structural capacity to bear the additional weight of these mechanisms.
Industrial electricity consumers sometimes follow a mixed approach when deploying solar power. Photovoltaic arrays are normally deployed on the rooftops of industrial properties, but ground-mounted arrays may also be viable if the company owns a very large extension of land.