Yellow Roof - Installing Solar Panels on Flat Roofs

Look Before You Leap!

Yellow roofs typically refer to roofs that have been equipped with solar panels or solar photovoltaic (PV) systems. These systems are designed to harness the power of sunlight and convert it into electricity, thereby reducing reliance on conventional energy sources and lowering carbon emissions.

We are frequently approached by customers who encounter leaks in the roof structure not long after having solar panels installed on an existing conventional (or regular) roof, initially not designed as an active roof. This leads to water damage to the building, significant financial burdens, and sometimes even a production downtime.

Upon inspection, it often becomes apparent that the issue is so serious that both the solar panels and the roof structure need to be completely dismantled, which, of course, leads to high costs. In this article, we offer some tips to help you enjoy your energy-efficient investment without worry.

Due to the permanent load of the solar panels and the necessary mounting system, most insulation materials begin to deform over time. This deformation creates stresses in the waterproofing, leading to cracks. These cracks, in turn, cause water leakage, resulting in water damage to the building. The consequences can be disastrous because once water or moisture has penetrated the insulation layer of an active roof, the material quickly loses its insulating capacity, and the expected energy savings are lost. Moist insulation never dries out even after repairing the leaks.

Therefore, it is crucial to use an insulation material that does not deform under permanent pressure and remains dry in all conditions. If rigid insulation is combined with a combustible steel roof, it not only adds additional rigidity to the roof structure but also provides extra stability, which is a major advantage when the roof is walked on for solar panel maintenance.

Solar panels are often located in close proximity to underlying building materials. If a fire occurs due to a technical defect in the PV installation, they pose an additional risk. The Prevention Brochure Solar Panels, published by the Insurers' Association, therefore explicitly advises against using flammable insulation in roof structures.

Insulation materials with a fire class A1 are a fundamental requirement for ensuring a safe flat roof. This approach allows for a reduced fire risk while also potentially lowering fire insurance costs.

It is increasingly common to see a combination of a yellow roof, covered with solar panels, and a green roof, a roof covered with vegetation. This combination not only creates an attractive visual contrast but also offers a range of significant benefits, making it a true win-win situation for both building owners and the environment.

Firstly, a green roof helps to reduce the temperature on the roof, which in turn leads to a higher efficiency of the PV panels. It has been shown that this reduction in temperature can result in an efficiency increase of 5 to 15%, which can mean substantial energy and cost benefits in the long run. Moreover, the lower temperature contributes to reduced expansion and contraction of the panels, significantly prolonging their lifespan and slowing down aging.

In addition, the presence of a green roof system increases the fire resistance of the roof. The vegetation helps to reduce fire spread, providing an additional layer of safety and protection for your building.

And we certainly should not overlook the general benefits of a green roof, which go beyond just the symbiotic relationship with solar panels. For more information about these benefits, we invite you to consult our [detailed text on green roofs](link to green roof text), where you will get an in-depth look at all the positive aspects a green roof can add to your home.

We are frequently contacted by customers who have had solar panels installed on an existing roof and are now facing roof leaks after only one or two years. This results in water damage to the building, substantial expenses, and sometimes even production downtime. On more than one occasion, inspections have revealed that the issue is so severe that both the solar panels and the roof structure have to be completely disassembled. In such cases, the unexpected costs obviously increase significantly.

FOAMGLAS® offers an additional service: Roofscan, a free, no-obligation roof survey. Specialists from FOAMGLAS® visit the site and conduct a visual inspection of the flat roof, both inside and outside, to assess its condition in relation to the building. A moisture measurement is then performed using a scanner. Depending on the results, at least one incision is made in the roof structure to visualize the various layers and determine whether the insulation is damp. A comprehensive report is compiled, including the necessary photos. If needed, a sample of the roof structure is also taken. Finally, a final recommendation is prepared in consultation with the decision-makers, with or without a budget estimate for the repair work.

"Our slogan is always: 'Look before your leap.' In new construction projects, it is important that flat roofs are properly designed with consideration for their potential use. Apart from pressure resistance and non-combustibility, the weight of the insulation layer may also be relevant here. This is in connection with the already anticipated weight of ballasted PV panels and maximum roof loads. Making adjustments afterwards will result in additional costs and a loss of raw materials, which is not socially responsible.

As a standard, flat roofs come with a 10-year guarantee. FOAMGLAS® provides clients with the option to extend this guarantee to, for example, 25 years. In this case, some well-defined rules and standards must be followed, from design to completion. The specific conditions are clearly outlined in an agreement. One of these conditions is the regular maintenance of the flat roof.

Conclusion

Before installing solar panels on a flat roof, certain conditions must be met:

The insulation material must be non-combustible (fire class A1).
The insulation must be able to sustain the permanent load without deforming. For easy maintenance of the PV system, the roof structure must also be walkable.
The roof structure must be suitable for solar panels. Existing flat roofs can be examined with Roofscan, an additional service from FOAMGLAS®, free of charge and without obligation.
Water leaks through a flat roof can have crucial consequences. Ensure good detailing and try to penetrate the waterproofing package as little as possible.