Solar roof with 11,000 panels for a carbon-neutral commercial building

Centuries ago, tulip bulbs were so precious that they were more expensive than houses. And while today the ‘tulip mania’ is nothing more but a historical anecdote, the delicate nature of flower bulbs still requires special growing and storing conditions. Royal de Ree Holland is a leading Dutch producer of flower bulbs whose giant factory building in Lisserbroek needed a thorough roof makeover to ensure optimal interior conditions. The plan also included fully embracing sustainability by going carbon-neutral and energetically independent.


Lisserbroek, The Netherlands

Project completion


Project type


Building type


Roof surface

ca. 33,000 m²

Roofing membrane

Elevate RubberGard EPDM 1.5 mm

When it comes to introducing sources of renewable energy, solar roofs are an extremely efficient solution. They do, however, require a solid roofing system under the panels. If the longevity of the roofing system turns out to be shorter than the lifespan of the photovoltaic system, the only option is to remove the solar panels in order to renovate the roof. An unimaginable perspective if, like Royal De Ree Holland, you plan to install 11,000 solar panels. 


With their life expectancy of over 50 years, high UV resistance and low maintenance requirements, EPDM membranes are among the most logical choices for solar roofs. The solution proposed for Royal de Ree Holland was a single-ply RubberGard EPDM roofing membrane installed directly over the existing roof. Thanks to the fully safe, flame-free installation process, the contractors were able to work on the roof of the functioning building, finishing slightly ahead of the deadline.

The brand-new solar roof of Royal de Ree Holland has been nominated for the Roof of the Year Award in the Netherlands.


Solar panels


Elevate RubberGard EPDM roofing membrane


PIR insulation (AK)


Bitumen membrane (old roofing system)


Mineral wool insulation (old roofing system)


Vapor barrier membrane


Corrugated steel

There is a lot to
discover about EPDM

EPDM is the most future-proof roofing solution when it comes to sustainabilityperformance and design freedom. Learn more about the role it played within this project and many others by discovering its benefits.

How did EPDM elevate this project?


The UV resistance of EPDM is the highest among all available roofing solutions. It lasts longer than the solar panels, which allows to create sustainable, low-maintenance solar roofs that function for many decades.

Quick installation

Installing EPDM is fast, flame-free and safe for people and the environment. When it comes to large roof surfaces and irregular shapes and forms, EPDM ensures a swift and easy installation process.

Reduce – Reuse– Recycle… How does EPDM score?

Waste is a very important topic in discussions on fighting climate change. Reducing, reusing and recycling are the imperatives valid that apply to everyone, and on whatever scale. Still, there are domains that should pay special attention to the materials use. Construction is certainly one of those domains, with construction and demolition waste (CDW) accounting for approximately 25% - 30% of all waste generated in the EU. EPDM can help significantly reduce the environmental impact of buildings. Here’s why.