....about photovoltaics on flat roofs


Penetrating a flat roof membrane creates a higher risk of leaks. Puncturing the waterproofing on a perfectly sound flat roof to install a mechanically fixed PV system seems to go against sensibility. Systems using membrane to membrane welding to secure the support structure seem the wisest. 


A ballasted PV system can increase weight loading enormously. Lightweight, less invasive solutions are available. 


The roofing membrane should last the design life of the PV system otherwise any refurbishment of the waterproofing will have to include removal and refitting of the solar panels. 


Maintenance is minimal but will be required. Access for maintenance should be sufficiently robust so as not to compromise the integrity of the waterproofing. 


The optimum panel angle for a flat roof mounted PV solution is not always just the most efficient output per panel. Roof size, wind loads and roof type can also impact on array design.