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Photovoltaic systems - caution during installation and operation

from
Prof. Dr. jur. Wolfgang Weller
Lawyer
Specialist lawyer for construction and architectural law

Give me a call: 0261 - 404 99 26
E-Mail:

Whether as an investment or out of personal conviction, a large number of homeowners are currently considering installing a photovoltaic system on the roof of their property.

In principle, this is possible with a suitable alignment and roof pitch of a pitched roof. However, due to their size, flat roofs of industrial and commercial buildings are particularly interesting. Here, the photovoltaic modules are mounted on additional substructures with the appropriate alignment and inclination.

Despite the economic and ecological advantages, every owner should be aware of the risks and disadvantages for the building fabric, in particular the roof covering, that are associated with this investment. This applies even more if the property owner does not operate the system themselves, but leases the roof area to an investor for the purpose of constructing and operating the photovoltaic system.

Of course, it should still be the case that the supporting structure, including the roof construction, must be checked for suitability before installation. The additional loads caused by the structure must be taken into account statically. In addition, however, static proof must also be provided for the structures themselves. In particular, the wind loads must be checked for the freestanding systems that are regularly used today.

Of course, the additional load must not reduce the calculated reserves for possible snow loads.

The keyword "snow" must be given special consideration when deciding on a photovoltaic system, especially when leasing a flat roof area for a photovoltaic system. Recent winters have shown that snowfall can reach or exceed the static reserves. The pictures of roof surfaces that had to be cleared by hand to avoid the risk of collapse have been all over the media. The actual difficulties of snow removal after the installation of a photovoltaic system are regularly overlooked. The spaces between the uprights are inaccessible, and connecting bridges are an additional hindrance. Unless otherwise specified in the lease agreement, the owner/lessor remains responsible for clearing the snow and has to bear all additional expenses.

Regardless of weather-related damage, it must also be considered that, with fundamental static suitability of the roof surface and the materials used in the roof structure, there is a risk of damage due to the construction and permanent walking on the surface. It is essential to determine the condition of the roof before installation begins.

The owner should have the compatibility between the roof cladding and all materials/building protection mats used in the course of installing the photovoltaic system confirmed. You should not rely on the installer's self-certification here, but rather get them to obtain approval from the manufacturer of the roof covering used. Incompatibility, in particular plasticizer migration, can cause considerable damage.

Another issue that is often overlooked is the load on the roof insulation. The basic suitability of the insulation for absorbing the additional loads must be checked before construction. In addition, however, it should also be noted that the confirmation of the absorption of the static load does not allow any conclusions to be drawn as to how the insulation will behave when subjected to permanent loading due to people walking in the spaces between the installations. This unforeseen load can lead to the insulation completely softening and caving in, resulting in puddles forming and mounting anchors protruding, causing the roof covering to rub against them. This can also lead to damage after only a short time. As a rule, the walkways and transport routes on the roofs in the area of the spaces between the systems must therefore be specially protected. When agreements are made for the construction of photovoltaic systems or for the leasing of roof surfaces for the purpose of constructing photovoltaic systems, a clear contractual assignment of responsibility is necessary here.

Finally, in view of the regularly long durations of the feed-in contracts (20 years or more), a regulation for possible maintenance and renovation work on the roof cladding must also be included in the contractual design. Even with minor work, parts of the system may have to be dismantled. This results in additional expense and lost revenue. This applies even more if a general renovation of the roof should become necessary during the operating time of the system or the lease period.

The above problem areas are only examples and by no means exhaustive. When the decision to install a photovoltaic system is pending, the property owner should not be pushed into hasty decisions by promises of high returns or easy-earned rent. A technical and legal review, the latter by a lawyer specializing in construction law and familiar with the subject as a whole, is advisable in any case.

The statements represent initial information that was current for the law applicable in Germany at the time of initial publication. The legal situation may have changed since then. Furthermore, the information provided cannot replace individual advice on a specific matter. Please contact us for this purpose.