The importance of ballast systems in photovoltaic installations.
A solution to address flat roofs of industrial buildings.
When the roofs of industrial buildings are completely flat, covered with insulating material, and therefore not suitable for aluminum support structures for photovoltaic systems, or when the project involves fixing photovoltaic modules to the ground, ballasts can be the optimal solution.
What are ballasts?
Ballasts are modular support structures, individual elements, that utilize weight to ensure the stability of photovoltaic modules.
They are placed on the surface in question, and their primary material is concrete, which allows for the creation of elements with different shapes depending on the characteristics to be adopted and thus ensures very low wear over time.
Separation elements are inserted between the support surface and the ballast to eliminate any effects of wear on the surface.
The only constraint to which ballasts are subject is their weight; therefore, a surface capable of resisting the compressive stresses they can generate is necessary.
Gruppo Inveco has installed several systems with ballasted support systems.
Let's take a look at some of them together.
Modulo S.r.l., Umbertide (PG) – 20° ballasts
In this installation, the ballasts have allowed for the utilization of a roof with an irregular shape and a surface unsuitable for the installation of photovoltaic modules with other types of supports.
Ballasts of this type have enabled the tilting of the photovoltaic module to an optimal tilt angle (20° in this case) to leverage the south-facing orientation of the roof.
The L-shaped design ensured a compact weight of the ballast (approximately 60 kg), allowing for navigation around obstacles on the roof, maximizing available space, and avoiding potential shading issues.
Plados S.p.A., Montecassiano (MC) – 15° ballasts
The company Plados S.p.A. is characterized by the presence of two regularly shaped, south-east-facing flat roofs (30° from south for one roof and 35° from south for the other).
The design choice was to maximize the installable power on the available surface of both roofs.
How? By applying ballasted systems to the design criteria.
> Geometric criterion: the layout of the modules follows the geometry of the roof, ensuring regularity and maximizing the occupied surface. Ballasts allow modules to be freely fixed in a given space because they are simply placed on the surface being worked on.
> Manufacturability criterion: given the company's location and therefore the available sunlight hours, a ballast with a moderate inclination (15°) was chosen to limit shading between rows while simultaneously maximizing the hours of sunlight during the day, ensuring optimal system manufacturability.
Rustichella d’Abruzzo S.p.A., Moscufo (PE) – 8° ballasts
Rustichella d’Abruzzo SpA, based in Moscufo, operates a production facility with various types of roofs, including a significant portion comprised of a flat roof with bituminous membrane.
With the goal of maximizing installed power and system productivity, we designed an installation on ballasts with an east-west orientation to broaden the daily production curve of the photovoltaic system, better utilizing the early morning and late afternoon hours of the day and achieving an excellent ratio between the surface area occupied by photovoltaic modules and the available space.
In an east-west installation, continuity between modules can be ensured, avoiding shading between rows.
In conclusion, the three examples presented in this discussion demonstrate the great versatility of ballasted support structures.
They assist the designer in selecting the optimal solution for the type of roof, meeting the needs of the customer.
Gruppo Inveco has other photovoltaic installations planned on ballasted systems, both on rooftops and on the ground.
In-depth analysis by Giuseppe Gallo - Technical Office, GRUPPO INVECO
