The use of a ballast-free mounting system makes it possible to build a support structure for PV modules without any additional load. In the case of roofs, this system requires the fixing points to be sealed. The connection of the substructure to the roof is carried out with screws, bolts or pins. A PV installation on a ballasted substructure is shown in the following Fig. 1.

Figure 1: PV installation installed on a flat roof using SolTech Service's ballast-free mounting system. Photo used with permission of SolTech Service.

Mounting a photovoltaic system without ballast can be divided into several stages.

• The first stage of installation consists of planning the placement of the angular substructure at the right angle with appropriate distances between its rows to avoid shading. Fixing the substructure to the roof is done with screws, for example. In the case of a sheet metal roof, identify the locations of the rafters where the screws must be screwed in. An example of how to fix a substructure to a concrete roof with screws is shown in Fig. 2.

Figure 2: Aluminium support structure without ballast bolted on a flat roof – installation systems by KENO Sp. z o.o. Photo used with permission of KENO Sp. z o.o..

When the structure is installed on the ground, care must be taken to ensure that there is a suitable foundation, which should form the basis for the entire length of the support structure. It is also permissible to use three-point support by using, for example, prefabricated concrete blocks filled with concrete to a depth of about 70 cm. An example of such a solution is presented on Fig. 3. In this case, the structure is attached to the foundation with concrete screws. There are also used structures screwed into the ground without the need for a concrete foundation.

Figure 3: Assembly of a support structure to concrete precast elements for a photovoltaic system installed on the ground – KENO Sp. z o.o. assembly systems. Photo used with permission of KENO Sp. z o.o..

• In the second step of the assembly, aluminium profiles are attached to the angular substructure, to which the photovoltaic modules are screwed using clamps. The positioning of the clamps is carried out by inserting the appropriate number of sliding grooves into the profiles at intervals equal to the width or length of the panels in the case of vertical or horizontal arrangement of the modules respectively. The installation of the profiles into the angular substructure and the positioning of the clamps is shown in Fig. 4.

Figure 4: Arrangement of a) aluminium profiles on the supporting structure together with b) location of the sliding sockets – KENO Sp. z o.o. assembly systems. Photo used with permission of KENO Sp. z o.o..

• In the third step, the photovoltaic modules are screwed on using clamps. An example photovoltaic installation with a horizontal arrangement of PV modules is shown in Fig. 5.

Figure 5: Photovoltaic panels mounted on a flat roof using aluminium support structure without ballast – installation systems of KENO Sp. z o.o. Photo used with permission of KENO Sp. z o.o..