When they are combined.
Pv on green roof.
Research has shown that the evapo transpiration from your green roofs vegetation can have an extremely positive effect on the efficiency of pv panels.
While as a rule the substructure is mounted in such a way that the solar panels are at a height of 10 to 20 cm green roofs require a distance of at least 35 to 50 cm from the roof.
The pv panels should also increase the diversity of vegetation and therefore also fauna using the green roof.
It is suggested that the panels optimum efficiency is at an ambient air temperature of approximately 25 c.
Green roof and solar photovoltaic pv systems are two technologies that could contribute to sustainable building development and reduction of greenhouse gas emissions.
Silicate pv panels work optimally at around 23c and american research including on city hall in chicago has shown that green roofs maintain the ambient air temperature at around 25c.
For every degree above this the pv panel can lose anything up to 0 5 efficiency.
The green roof element provides the ballast to hold the a frames and panels in place.
Certain characteristics of the plants lead to improved pv output and the modules protect the plants from high irradiance rates levels.
A green roof makes the installation of a frame panels easier.
In order to minimise any shading from the vegetation and to protect the microclimate on green roofs the pv modules are mounted higher.