But that was just 'in short', taking the process in whole it will begin with replacing the usual mesh shading, the 'eye lash' by edge-protection scaffolding around the perimeter of the roof which is pretty steep. The domed roof comprised of a corrugated roof sheet, a vapor barrier and mineral 'rock wool' insulation covered by a waterproof membrane is later modified by the roof designers and installers. They cut through the waterproof membrane and remove the insulation.

Next, the stainless steel brackets which help to hold the rails is drilled and riveted to the corrugated roof sheet helping to place the PV panels on those rails. A new piece of insulation cut to size is seated neatly over the bracket with a new waterproof membrane heat sealed. Just fitting them won't help, they are tested with a combination of high-voltage testing and water/vacuum testing with fluorescent dyes to ensure everything is right and in place.

The roof rails are fitted on the post to clamp the PV panels on these rails forming concentric circles around the roof. Normal PV panels are rectangular and come in an aluminum frame with 36 cells and a total peak output of about 85 Watts. The City Hall's panels are trapezoidal and bare unframed glass -special black color. Every single panel are packed up to the same height as its neighbor and adjusted so that the radial lines between sectors are straight and each row forms concentric circles with uniform gaps. Wiring looms were further installed for roof penetrations to the inverter location

Incidentally the London City Hall is amongst the largest translucent glass-glass photovoltaic laminates made in the UK so far! (~2m x3m)