It sounds like science fiction: a feather-light solar generator hangs above a public space, its light, swaying form casting a pattern of shadows like leaves on a tree. But it’s real: individual solar cells are suspended from a net of steel cables, generating electricity at the same time as casting shade on the space below and protecting it from the elements. And it’s eye-catching, too.This giant leap in solar technology uses flexible organic photo-voltaic (OPV) modules on an extremely lightweight structural rig. Designers have the freedom to finally escape from the roof and walls of a structure and bring solar facilities into a three-dimensional space, with all the possibilities that come with it.

Feeding the Planet, Energy for Life” is the theme for Expo 2015. The German pavilion clearly orients itself to this leit-motif – under the “Fields of Ideas” motto. Germany reveals itself as a vibrant, fertile “landscape” filled with ideas on future human nutrition. The pavilion vividly illustrates just how important dealing respectfully with nature is to our ongoing food supply, while inviting visitors to take action themselves.

Visitors can discover the “Fields of Ideas” along two different routes. They can either stroll along the pavilion’s freely accessible upper level, which invites them to relax and enjoy. Or they can explore the exhibition inside the pavilion, which addresses such topics as the sources of nutrition, through to food production and consumption in the urban world.

The central design element of the pavilion are expressive membrane-covered shelters in the shape of sprouting plants: the “Idea Seedlings.” Their construction and bionic design vocabulary are inspired by nature. The Idea Seed-lings link the interior and exterior spaces, a blend of archi-tecture and exhibition, and at the same time provide shade for visitors in the hot Italian summer.

An innovative technology

By integrating cutting-edge organic photovoltaic (OPV) technology, the seedlings become Solar Trees. The German Pavilion is the first large international architecture project to use these innovative new products. In contrast with a project using conventional solar modules, the German Pavilion architects had the opportunity to do more than just incorporate existing technology. They had free rein to design the flexible, OPV membrane modules to match their own creative ideas, and to integrate them into the overall design of the pavilion.


The Solar Trees are the first exhibits in which OPV has been printed in industrial production. This is a milestone in the development of the technology.

David Müller, Head of Photovoltaic Marketing at Merck

Project steps

  • Design & project planning
    June - September 2014
  • Production of OPV & pre-assembly
    September 2014 - February 2015
  • Installation & commissioning
    March 2015


Mission Stakeholder
Overall design Schmidhuber Architekten, ASCA
Technical system development ASCA, Merck, Carl Stahl, Lapp
Module design and manufacture ASCA
Electrical system (incl. design) ASCA, Lapp
Mechanical system (incl. design) ASCA, Carl Stahl
Pre-assembly ASCA
Installation Carl Stahl, ASCA


Total occupied surface: ≈ 120 m2


German Federal Ministry of Economics

OPV Solar Trees at EXPO 2015