Green roofs can increase the efficiency of PV panels. Not only can a living green roof hide a solar panel and improve the appearance of your roof, it will also increase the panel’s efficiency.
Opportunity not conflict
Often approached as independent sustainable systems, both green roofs and solar panels have their own attributes. Nevertheless the combination of the two is becoming ever more appealing. Both technologies can compliment one another and their environments. A prime example of an ecosystem-services approach to the built environment.
A green roof provides numerous benefits to the environment. From insulation and sound reduction, to a decrease in the Urban Heat Island Effect and an increase in biodiversity. Meanwhile the uses of Photovoltaic (PV) panels on a roof top provides a renewable source of energy for your building. Beyond these related advantages, these two systems can in fact support one another.
A cool green roof increases efficiency
Research has shown that the evapo-transpiration from green roof vegetation can have a positive effect on the efficiency of PV panels. The panels’ optimum efficiency occurs at an ambient air temperature of approximately 25 ̊C. For every degree above this, the PV panel can lose anything up to 0.5% efficiency.
A traditional roof can become extremely hot when in direct sunlight, especially in the height of summer. Exactly when solar panels are designed to be at their peak energy production. But this extreme surface temperature can have an adverse affect. As your green roof transpires, so the surrounding air can maintain an ambient temperature (between 20-28 ̊C); sustaining the efficiency of the PV panels. In turn producing far more reliable power during the summer months.
A green roof benefits from PV Panels
PV’s will also create a shadier habitat for a more diverse number of species. Although plant growth may be stunted because of the lack of sunlight, this is offset by the water run-off from the surface of the panels, concentrating moisture at the foot of the panel. This results in a more diverse range of vegetation than would commonly be expected on a fully exposed extensive green roof.
When the rainfall is less, your green roof will reduce air born pollutants and dust. By reducing the amount of dirt on the photovoltaic panels, your green roof is increasing their chances at performing at a higher standard as well as minimising their need of maintenance.