Expanding Solar Energy to Buildings with Limited Roof Capacity

Not all buildings can accommodate the weight of standard solar panels, yet the need to improve energy efficiency remains just as important. By adopting lightweight and flexible PV modules, ZDR Investments can bring renewable energy to structurally sensitive rooftops and broaden the solar potential of its portfolio.

Renewable energy plays an increasingly important role in enhancing the operational efficiency and long-term sustainability of real estate assets. At ZDR Investments, photovoltaic (PV) systems are a key component of this strategy. However, not every building is capable of supporting the weight of conventional PV panels. Some roofs — especially older structures or buildings constructed with lighter materials — have limited load capacity that prevents the installation of standard glass modules. To ensure these properties can still benefit from clean energy generation, we have introduced a lighter and more adaptable PV technology that enables solar deployment even in structurally constrained environments. This solution has already been implemented on two properties within our European portfolio.

Introducing Lightweight Composite PV Modules

Every PV installation begins with a detailed structural review of the rooftop. These assessments occasionally reveal that a building cannot support conventional PV systems, which rely on heavier, glass-based modules. Rather than excluding such assets from our renewable energy programme, we sought a solution that would enable us to integrate solar power while working within strict weight limits.

Working closely with specialist suppliers, we adopted a new generation of lightweight PV modules manufactured from advanced composite polymer materials. Unlike traditional panels, these modules do not require a glass front sheet, which significantly reduces overall weight while preserving electrical performance and weather resistance. A typical panel measuring 2100 × 1100 × 2 mm and producing 430 W weighs only 7–8 kg — far below the weight of a standard glass module. Installation is also streamlined, as the panels are adhered directly to the roof surface, eliminating the need for mechanical anchoring or penetrations that could compromise the roof membrane.

First Deployments in the ZDR Investments Portfolio

This technology is now in operation at two ZDR Investments properties. The retail park in Rakovník, Czechia, is equipped with a lightweight PV installation totalling 49.92 kWp, while the system at Flex-space Plzeň reaches 318.2 kWp. Both projects demonstrate how composite modules can unlock solar capacity in locations where conventional PV installations would not have been structurally feasible.