Why not use the roof space for solar panels instead of a green roof?
The two are actually mutually beneficial. The cooling effect of green roofs can improve the efficiency of solar panels (also known as photovoltaics [PV]). The shade provided by the PV units can also enhance the biodiversity potential of the green roof. Plant species must be carefully selected to suit the partially-shaded conditions, enabling the full benefit of a green roof installation to be realised.