Special Show "Green roof / Usable roof space"

The special show "Green roof / Usable roof space" was a "living workshop" with numerous events and a live demonstration of skilled roof greening, with a presentation of the best concepts and solutions.

The solar roof tile

A concept study for a sustainable solution for energy generation on rooftops of existing buildings.

RheinEnergie and the Cologne-based engineering firm paXos collaborate to present a concept study for a sustainable solution for energy generation on the roofs of existing buildings. The concept study was developed by paXos. The current prototypes were manufactured by Continental by order of RheinEnergie and were first presented to the public during the E-world at the start of February 2018. At DACH+HOLZ International's special show "Green roof / Usable roof space" the innovation was presented.

The innovation consists of the intelligent combination of components from automobile manufacturing and the length-adjustable, patented Klick-in system used to connect the roof tiles to each other.

The materials and components from automobile manufacturing are generally exposed to harsher conditions in regard to temperature, pressure, vibrations, drag, and impact resistance. This ensures that the solar roof tiles will be able to withstand the conditions on the roof without problems and for a long duration.

The solar roof tile (SRT) offers the following advantages over conventional solutions (performance according to Standard Test Conditions, STC):

  • Improved energy yield per square metre of roof surface (heat and electricity):
    Heat per sq. m: Conventional: 250 Watt, SRP: 300 Watt
    Electricity per sq. m: Conventional: 100 Watt, SRP: 144 Watt
  • Improved appearance: from 5 metres away, the solar roof tiles are barely distinguishable from black varnished roof tiles. Optionally, the tiles can also be produced in brick red or blue.
  • Dimensions, weight, as well as laying and handling are the same as normal roof tiles (important for the roofer).
  • The patented, length-adjustable klick-in system allows the roofer to lay the tiles quick, easy, and securely and saves assembly costs.
  • Increased electricity yield in midsummer due to the cooling of the wafer through the integration of solar heat. This also increases the lifespan of the wafer. (This is a decisive competitive advantage over all competitors currently in the market!)
  • Solar roof tiles can be retroactively replaced or exchanged, if required (e.g. to install roof ventilation, windows, antennae, satellite dishes, or roof treads; this option is also not available with most competing products).
  • The solar roof tiles are supplemented by so-called "complementary roof tiles", a cost-effective, black varnished, concrete roofing tile which will be integrated in all those locations where installing a solar roof tile is either not sensible or not desired. Visually, the complementary roof tiles are barely distinguishable from the solar roof tiles.
  • Better secured against storm suction than conventional roof tiles.
  • Cooling of the attic during midsummer.
  • Defrosting option through thrust-reversal in regions with very snowy winters. This allows for a higher energy yield during the colder season.

RheinEnergie and paXos plan to continue pushing the project forward together.

Due to the intelligent construction and the use of components and materials commonly used in automobile manufacturing, the solar roof tiles will be available at a competitive price.


obenplus® is an online platform to generate sustainable programmes and diverse opportunities for retroactive densification through the addition of storeys in urban areas. Illustrative and aesthetic impulses on the platform provide incentive to find new uses for the underused roof spaces on buildings. The focus here lies in harnessing the potential of retroactive densification through rooftop conversion and the addition of storeys to maintain a sustainable structure for a social blending across the entire cityscape and to expand it for the future.

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