Can you combine green and blue roofs with solar PV?
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With modern planning conditions, most local authorities require new buildings to include both a green roof and a significant percentage of site sourced renewables; and if the construction is to be sited in a flood hazard area it must also incorporate a viable SuDS with defined allowable discharge rates. Architects are compelled to deliver a win-win scenario where the technologies are each given the full useable roof area. So, is this scenario too difficult to fulfil, or entirely possible? Tom Raftery, Bauder's Solar PV product manager, explains.
Bauder has a unique
solar photovoltaic (PV) mounting system,
BioSOLAR, that is specifically designed to allow the combination of biodiverse green roofs and solar PV whilst having the ability to be installed atop our SuDS blue roof void construction.
The PV system utilises the green roof substrate as ballast removing the need for penetrating the waterproofing to secure the mounting units to the roof and ensuring that the entire roof area can be considered a biodiverse green roof. The void structure beneath allows free-flowing water movement to specifically engineered outlets that restrict the water discharge to meet planning requirements.
The initial step into deciding what the significant design considerations are is to understand the weight loading of the attenuated rainwater to meet the project specific discharge rates of the SuDS report as well as including the BioSOLAR green roof loading. From there, more than any other type of flat roof, it is important to avoid, and wherever possible eliminate, penetrations through a blue roof.