Types of supporting structures. How to choose the right one?

When faced with the selection of individual photovoltaic components, we first focus our attention on the modules and the inverter, while – which should not be forgotten – the basis of the entire installation are properly selected photovoltaic racks. Therefore, in today’s post, we will focus on this issue, explaining what types of support structures are available on the Polish market and indicating which of them will be appropriate for the needs of a specific implementation. We cordially encourage you to read the article.

What structure should be used for solar panels?

The basic division criterion when it comes to supporting structures for photovoltaic panels is the planned location of the system and the related type of surface on which it is to be installed. In this respect, therefore, stands dedicated to free-standing installations as well as flat or sloping roofs. In the latter case, compared to the other two, you can count on the lowest costs of the project, because the structures placed on the slope use a specific degree of inclination, which significantly facilitates their assembly. However, it should be taken into account that the final installation will achieve optimal efficiency only on buildings with a south, west or east azimuth.

Therefore, it is worth remembering that the basic selection factor related to a specific type of photovoltaic rack is the intended area of installation of the PV installation. As part of e.g. houses with north azimuth, it may turn out that we will be forced to give up the roof supporting structure and instead put on a free-standing variant, which in turn will also affect all other aspects of the project.

Photovoltaic racks depending on the type of roofing

Since we have already discussed the first stage of selecting the supporting structures for PV installations, let’s move on to a bit more specific issues, i.e. the type of substrate within which the system is to be installed. While there are many options available for free-standing installations, in the case of roofs, the choice of a specific solution is closely related to their specificity.

Assuming that we need to choose a frame suitable for a sloping roof, in this respect, we will find models of photovoltaic frames on the market dedicated primarily to ceramic tiles, metal roof tiles, plain tiles, as well as trapezoidal roofs and shingles, roofing felt and seam sheet. Then the type of structure results strictly from the type of roofing, and our choice is basically limited only to determining its orientation (vertical / horizontal).

The situation is slightly different in the case of flat roofs, where the room for maneuver is slightly larger. What structure for solar panels in such circumstances? We have 4 different options to choose from:

• racks attached to the roof deck with concrete blocks – this method provides the installation with maximum wind resistance,
• frames with ballast in the form of concrete blocks,
• consoles made of plastic and filled with gravel or concrete blocks, to which PV panels are attached,
• free-standing supporting structure for photovoltaic panels based on special steel frames and pillars fixed to the roof.

When it comes to flat roofs, in practice, however, our choice will not be completely free. Due to the high risk of overloading them, in the event of choosing an inappropriate type of frame, this issue should always be consulted with a qualified specialist who – based on the specific parameters of the building – will ultimately decide what structure for photovoltaic panels can be used.

The supporting structure for photovoltaic panels and the material used for its production

Biorąc pod uwagę materiał, z którego wykonane są poszczególne rodzaje konstrukcji wsporczych dedykowane modułom PV, najczęściej przyjmuje się jeden z trzech możliwych scenariuszy:

• stelaże wykonane w pełni ze stali ocynkowanej ogniowo – zdecydowanie najtańsze, • konstrukcje otrzymane na bazie stali ocynkowanej ogniowo w połączeniu z aluminium, a także zespoleniami wykonanymi ze stali nierdzewnej – cena wyższa w stosunku do poprzedniego rozwiązania o średnio 10%, • stelaże wykonane wyłącznie z aluminium oraz stali nierdzewnej – najdroższe spośród konwencjonalnych opcji, o kosztach wyższych w porównaniu do modeli z ocynkowanej stali o około 30 do 35%.

Considering the material from which the various types of supporting structures dedicated to PV modules are made, one of the three possible scenarios is most often adopted:

• frames made entirely of hot-dip galvanized steel – by far the cheapest,
• structures based on hot-dip galvanized steel in combination with aluminum, as well as combinations made of stainless steel – the price is higher than the previous solution by an average of 10%,
• frames made only of aluminum and stainless steel – the most expensive among conventional options, with costs higher than those of galvanized steel models by about 30 to 35%.

Supporting structure for photovoltaic panels – which one is the best?

In terms of design features, photovoltaic racks are divided into many heterogeneous groups, of which in most cases it is difficult to indicate the absolutely best proposals. There is, however, an exception to this rule for installations mounted on a flat surface. In such a situation, the two-support models are the best solution. Due to their significantly reinforced construction compared to conventional solutions, they guarantee the highest degree of stabilization, as well as provide optimal protection against strong wind, snow, hail and rain, which ultimately translates into their long-term reliability.

Supporting structures for photovoltaic panels of this type can most often be found in free-standing systems, present in particular within photovoltaic farms, but they can also be successfully used on flat roofs made of very solid materials, such as reinforced concrete slabs.