The company, a division of Green Roof Service, calls its Sun-Root product the first fully integrated, non-penetrative solar and extensive green roof system in North America. Through the system, plants cool the roof through evaporation and transpiration – the emittance of water from leaves. This enables the solar panels to achieve greater efficiency, the company says.
Green Roof Service principal Jorg Breuning describes heat as “the enemy of energy production.” He says that whenever rooftop temperatures rise, PV elements lose their efficiency and can even shut down.
The core of the Sun-Root system is a drainage element stabilized by root stiffeners. This holds the solar power modules in place and conducts rainwater underneath the panels via a suction and capillary fleece, providing water to the plants and creating cooling through evaporation. (The diagram, above left, shows how the system works.)
The standard incline of the Sun Root is 30 degrees, but flexible adjustment is possible with a Root Flex retrofit kit, the company said.
Green roofs reduce roof surface and ambient air temperatures, and help to mitigate the urban heat island effect, the phenomenon by which urban areas experience higher temperatures than nearby rural areas. Heat islands are caused by a number of factors, but some of the major ones include reduced vegetation and increased impervious surfaces, such as conventional roofs, sidewalks, roads, and parking lots.
The EPA estimates that five to 10 percent of community-wide demand for electricity is used to compensate for the heat island effect.
More information on green roofs can be found in Issue 30 of EL Insights.