Photovoltaics is important both for the economy and the natural environment, and at the same time is a sustainable solution to the growing demand for electricity. Today, the offer of Polish companies operating in this field is impressive.
Due to the country of origin, 65% of the added value in the average photovoltaic installation came from Polish companies in 2018, and for some installations this share was 70% (in the case of using Polish inverters). These figures include the value of any license fees or foreign intellectual property rights. Apart from PV panels (which account for approximately 32% of the total costs incurred by the investor of a solar power plant in its life cycle), the rest of the elements are of Polish origin. And so, in particular, 100% Polish added value currently includes Polish companies that make the following elements of PV installations: transformer station, construction, fencing, monitoring, project preparation and disconnection to the grid, and Polish companies providing the following services for PV installations: O&M (operation and maintenance ), protection, insurance. Moreover, almost 11% of the total costs in the life cycle of PV installations are received by Polish land tenants and local governments in the form of taxes. At the same time, it is worth noting that we can already buy high-quality photovoltaic panels from Polish producers (e.g. Selfa, Solar Energy, Solar Future Energy, Bruk Bet), and serious discussions are underway regarding the construction of factories by Polish companies with production capacities exceeding 100 MW of annual production of panels (e.g. the KGHM project).
Therefore, investors can now choose solutions that 100% of the investment costs will come from Poland. According to the report of the Institute for Renewable Energy "The photovoltaic market in Poland 2018", there were 16 producers of photovoltaic modules in Poland during this period. As estimated, their maximum production capacity may be 580 MW per year, which is enough to cover the annual demand in Poland, so contrary to popular opinion, there is competition for panels from China. However, it must be realized that achieving a dominant role by Polish producers (without dedicated support) will be difficult. In addition to module manufacturers, other industries will also increase employment to carry out PV investments - developers, construction companies, suppliers of fastening structures, grid connection companies, security companies, etc.
One of the basic problems facing the further development of this industry today is to provide space for new installations in the public space. Building ground-based solar farms is not an optimal solution. It excludes large areas of land from normal use (e.g. agricultural). In addition, it requires individual protection. This type of installation is also not possible to implement in urban areas.
The optimal locations for photovoltaic installations are the roofs of industrial, warehouse and sports facilities. The vast majority of roofs of this type of newly built buildings are covered with sandwich panels with a PIR core.
Installation of photovoltaic panels on sandwich roof panels with a PIR core.
Today, manufacturers of photovoltaic panel fasteners offer a standard range of solutions for sandwich roof panels, used in the case of installation on a roof covered with ordinary trapezoidal sheet metal. So let's take a look at the typical solutions:
The photos above show the system of fastening with a rail screwed to the tops of the trapezoidal hump with sheet metal screws with a sealing collar. An additional gasket (usually EPDM) is used between the rail and the sheet.
The picture above shows the assembly on a multi-slot system mounting rail, which is attached to the roof with trapezoidal grips. Trapezoidal handles are matched to the shape of the sheet and attached to its sides with farmer's screws (six per handle). Also in this solution, a gasket is used between the grip and the trapezoidal sheet.
Both of the above types of solutions are currently the basic solutions used on roofs covered with sandwich panels. The main advantage of these systems is the simplicity and speed of assembly. Unfortunately, this is done with the need to make a large number of holes in the covering sheet. This results in specific requirements that must be met by a sandwich roof panel when using fasteners for photo panels. First of all, the key parameter in this case is the thickness of the upper, outer sheet of the sandwich panel.
As of today, there are no detailed strength tests allowing to precisely determine the relationship between the load capacity of the grip-plate connection as a function of the thickness of the sheet used and the type of steel from which it was made. The manufacturers of fasteners quite generally provide the minimum thickness of the cover sheet in a fairly wide range from 0.5 mm to 0.7 mm. In the case of sandwich roof panels under photovoltaic panels, we recommend that the minimum thickness of the top sheet is 0.7 mm. The thickness selected in this way should protect the contractor against the possibility of twisting the sheet metal screws in the sheet and thus losing tightness and load-bearing capacity of the connection. In addition, a sheet of this thickness will transfer the pressure loads and the tearing loads of the sandwich panel from the PIR core much better.
There should also be restrictions on the location of the fixing points on the roof made of sandwich panels. These points should not be established in the places where roof panel joints occur (longitudinal and transverse lock). The location of the handles in these places may cause the roofing to become unsealed. Remember that in the case of a sandwich panel, we do not have any additional protection in the form of an initial covering layer that occurs in classic roofs. This imposes an obligation to pay special attention to the quality of assembly of the elements of photovoltaic systems.
On the horizon, the need to introduce to the market a comprehensive offer of sandwich panel manufacturers in terms of photovoltaics becomes more apparent. From the customer's point of view, the safest solution would be to purchase a complete roof system with solar panel mounting elements from one supplier. This would allow a complete testing and certification program for such a kit to be carried out. It would also allow the customer to deal with possible proceedings resulting from the warranty provided by the manufacturer (one supplier - one warranty). We hope that this market gap will be filled in the near future.