Photovoltaic and green roof -A Trend Setting Combination


A solar plant for the production of solar electricity should produce as much yield as possible and be efficient at the same time. But efficiency depends on various factors. Firstly, the system must be optimally oriented towards the sun so that the sun’s rays are captured in the best possible way. On the other hand, the systems should be quick and inexpensive to install. Cooling can also help to improve the performance of the system. And these are precisely the challenges that planners and solar technicians have to face again and again.

Quick and cost-effective installation

A Solar green roof is installed as a load-bearing system without roof penetration. For this purpose, the Sun-Root photovoltaic elevations are fixed with the load of the green roof structure in a position and wind suction secure. An advantage of this system solution is that the photovoltaic supports do not interfere with the roof construction and roof sealing and do not require heavy point loads. Since the roof sealing is not broken, damage-prone roof sealing work is not necessary. In addition, the ballasted system is less expensive than conventional elevated supports fixed to the roof structure because of its less complex and quick installation. Usually a green solar roof will be designed in such a way that narrow rows of modules and thus high yields are possible even in small spaces. Since the vegetation runs underneath the modules, large parts of the roof surface can still be greened.

Green roofs protect the roof sealing and extend its service life

The green roof structure acts as a protective layer against extreme temperatures, UV and IR radiation, hail and weather influences. The service life of the roof waterproofing is doubled and the usual repair and renovation work is carried out much later compared to a non-green roof. This enables a long trouble-free operation of the solar system. The green roof structure also protects the sensitive roof sealing during the necessary maintenance work on the solar system. It is only important to ensure that the photovoltaic modules are not shaded by plants. If necessary, gravel strips must be inserted in front of the modules and higher plants should be removed during regular maintenance.

Rainwater retention and reduction of the rainwater charge

Even thin layers of extensive greenery in themselves hold back 40-70% of annual precipitation, depending on the location. Most of the retained water is evaporated again with the positive effects of cooling, air humidification and dust binding. The sewerage system is relieved, drains can be reduced, sewer pipes can be dimensioned smaller and rain overflow basins can be saved. These positive properties can be further enhanced by combining them with any retention solutions meander or restrictor, up to complete water retention on the roof.

Yield increase of the photovoltaic system due to the cooling capacity of the green roof

The operating temperature of the solar modules influences their performance. Temperatures above 25°C lead to a drop in performance, with module manufacturers generally assuming a loss in performance of around 0.5% per °C. However, the proven evaporative cooling of green roofs can increase the efficiency of the photovoltaic system by up to 5%.

Points to note during planning and implementation

With a green solar roof, all trades involved (roofers, garden and landscaping company, solar installer) should be consulted as early as the planning phase in order to coordinate the construction processes. The gardening and landscaping company can carry out the installation of the complete “photovoltaic green roof”, i.e. solar elevation and green roof construction. Before the vegetation is applied, the solar installer assembles the modules and carries out the electrical work. The vegetation work is carried out at the end so that the plants are not damaged.