First steps for planning PV on a flat roof

In the UK, solar photovoltaic (PV) is the most popular renewable energy and its deployment is rising rapidly across the globe, particularly because climate change and resource scarcity are on the agenda of every government and major corporation in the world. Despite recent UK Government policy changes, the number of large, flat roof installations should still rise as local authorities and businesses look to reduce their carbon footprint and gain energy security for the future.

All too often within the construction industry, photovoltaic specifications focus on energy efficiencies and outputs of the solar panels, omitting to give the same focus to ensuring the rooftop array is installed with methods that have as little impact on the building and its waterproofing as possible and that the array works to its maximum potential for its entire lifespan rather than just becoming a ‘tick box’ exercise to achieve sustainability credits.

This information is aimed at designers considering the inclusion of a PV array on flat roof construction projects and outlines the key elements to be mindful of to ensure the design is sustainable, protects the building and meets lifespan expectations.

We have two design guides to choose from with the first suiting a new build construction with the second suiting retrofitting a PV array to an existing roof:

PV design guide, detailing all relevant considerations specifically for new build applications.


PV design guide, detailing all relevant considerations specifically in retrofit applications.


The Climate Change Act established a target for the UK to reduce its emissions by at least 80% from 1990 levels by 2050.

Tom Raftery, PV Product Manager

“As rooftop solar PV arrays become a consistent element of both new build and refurbishment commercial building specifications it is vital that these schemes have a cohesive design approach that embraces all elements of the project at the planning stage. Understanding the building’s energy profile, the impact of the array on the building’s fabric and using the highest quality equipment throughout are all vital for success”.