Jason McCabe, Technical Director for the UK and Ireland at Clenergy, discusses the practical realities of commercial rooftop solar, from roof condition and structural checks to installation risk, mounting system design, logistics and the need for stronger industry standards.
PES: Thanks for taking the time to speak with us today. To start with, when you look at commercial rooftop solar right now, what is really driving whether a project is straightforward to deliver or becomes more complex than expected? A lot of that complexity seems to come down to the building itself. When you are assessing a commercial roof, what are the first practical factors that tend to shape whether solar is viable or not?
Jason McCabe: A lot depends on the load capacity of the roof, but equally important is the condition and age of the roof. Both the roof covering and the substructure condition are critical factors.
PES: From there, structural considerations often set the boundaries early on. What are some of the most common structural or design constraints you come across when working with commercial rooftops?
JM: Most commercial roofs were never designed with a future solar PV installation in mind. If it was designed correctly at the time, an allowance for wind loads and potential snow loads would have been included, so a combination of dynamic loads and environmental loads would have been used during the design and construction phase.
However, adding hundreds and sometimes thousands of panels to the roof or façade of a building significantly increases the applied loads. In an ideal world, every roof or building would have a condition report carried out. However, in reality, many do not do this, so we may receive a loading report on the ability of the roof to withstand the additional weight being applied.