pv magazine Spotlight: A PV mounting systems for bigger format solar modules

There is a trend to larger PV module sizes. What did you have to change to adapt your flat roof mounting systems to these larger formats?

Due to the increasing demand for more powerful PV modules, which ideally should not be more expensive, the dimensions are currently changing very quickly. This is because more power usually means a larger module area or the use of high-performance modules, which would make systems in the commercial sector much more expensive. Accordingly, increasingly large modules are being used, especially in the commercial segment. This is why we have designed our new IBC AeroFix G3 mounting system in such a way that there is considerably more leeway when it comes to module lengths and widths, and larger modules can also be installed. To achieve this, we have now equipped each support with a sophisticated tilt joint. This ensures mechanically stress-free support of the modules. In addition, we have also enlarged the supports, as the installation angle should not change despite the increasingly wide modules. More information on the tilt joint and its function can be found in the pv magazine Spotlight on September 23.

On which construction detail does the mechanical stress on the PV module depend? And how much mechanical stress is allowed under the terms of the module warranty? Furthermore, is there evidence that mechanical stress induced by the mounting system sometimes leads to performance losses?

Of course, a module's durability depends primarily on the module itself. For example, it depends on how rigid the frame and the glass of the module are. There are quite serious differences in the market. To enable consistent flexibility of the module and not to bend the frame over a rigid support edge, the aforementioned tilt joint comes into play. Thanks to this, the module rests on the mounting rail without tension. This in turn minimizes the risk of cell damage and associated power losses.

The various design options of the AeroFix G3 also facilitate an increase in the maximum possible module load. However, this varies between module types. That’s why we test the maximum approvable load for each module and design variant individually by means of our in-house tests in the SUNLAB test laboratory. The customer can rest assured that IBC Solar modules and brackets are perfectly suitable for each other and that together they deliver maximum performance and service life.

Apart from the adaptability to various PV module sizes, is there any other feature you added to the new mounting system?

Yes, for example, we have optimized the cable installation. The wide base rails have integrated cable ducts that can accommodate up to 28 6 mm² cables. The top supports are equipped with an extra shelf to attach a small cable duct or cable clips.

The wide and more affordable narrow eco base rails can also be combined as required for the first time. However, the roof construction and the maximum possible surface loads on the covered roof area must be suitable for this purpose. If this is the case, the combination of the profiles achieves even higher construction cost efficiency.

Did you have to conduct new wind tunnel measurements? If no, why not? If yes, please elaborate on the findings. Is there anything surprising compared to smaller modules?

Detailed tests in the wind tunnel are not a requirement. Although there is the Eurocode DIN EN 1991-1-4:2010-12 which regulates the effects on structures, PV systems are not taken into account. As a quality provider and guarantor, IBC Solar is not prepared to be content with this. Therefore, dedicated tests in the wind tunnel are part of the standard procedure when we develop new products. This is the only way to determine realistic wind loads acting on the product. With these findings, we are able to design the AeroFix G3 as efficiently and economically as possible. This enables us, for example, to calculate the required ballast as low as possible and to design an aerodynamic system that usually does not require any screws or drilling and therefore does not penetrate or damage the roof cladding.

In addition, the system also meets the latest requirements of the Wind Technology Society.

In general, the aerodynamic systems segment is still very young. However, the knowledge base has increased over the past few years and the requirements for the tests are becoming increasingly precise. For example, there has been a change in the definition of roof zones. Previously, there were only three defined roof zones, on which the wind acted in varying degrees. Today, up to nine zones can be defined on the roof.

Is there a difference in installation time when using 500 W PV modules instead of 350 W modules, for example? Is there anything else to consider in terms of installation?

The capacity of a module is initially of secondary importance for the mounting and there is no difference in the assembly time per module. However, if the module becomes too long and too wide, you may have to install additional base rails and supports. This, of course, costs time and money. In addition, it must be noted that large modules can no longer be carried by a single installer due to their weight.

What is the market penetration of large-scale PV modules in the rooftop segment in different target markets, and how do you expect it to develop?

The regulations in Germany differ considerably compared to other European countries. While modules with a surface area of more than 2 m² may not be installed on roofs in Germany, for example, these modules are popular and permitted in other European countries.

In Sweden, black modules with a surface area of 2.2 m² are already being installed in the domestic sector. Next year, we expect an increase to approx. 540 Wp (2.5 m²). The reason for this is that in Sweden, the regulations stipulate that two people must work with one module on the roof. Therefore, it is more efficient if these modules are as large as possible.

Similar trends can also be seen in Spain and Poland. It is estimated that mainly modules with a capacity of 450 or 540 Wp will be used in the commercial sector next year. Depending on the manufacturer, this corresponds to an area of 2.2 m² or 2.5 m².

Overall, we expect that these large modules will make up 30-40% of the roof-mounted sector in the foreseeable future.

Are there roof types where it makes sense to keep using smaller-scale PV modules?

Every roof is different. If, for example, the roof has a lot of disturbing objects such as continuous roof lights, ventilation, or similar, it may be advisable to use smaller modules. In such cases, these allow better use of the area and it may even be the case that one module more per row fits on the roof. This means that the system may have the desired higher nominal output despite using smaller modules.