Solar Energy Built In

Traffic, industry, buildings and lots of people living together in a confined space make cities real energy guzzlers. They consume 80 per cent of the energy generated worldwide and emit 85 per cent of all greenhouse gases. [1] In the European Union alone, buildings account for more than one third of total energy consumption. [2] In the future, a building’s entire electricity needs could be covered by green electricity from solar energy – thanks to organic solar cells on facades or roofs. Today’s solar technologies are still not very flexible in their designs and are often not compatible with aesthetic demands.

Second skin

For this reason, organic solar cells (also known as organic photovoltaics – OPV) are being developed in Germany, Brazil and other countries. Instead of silicon – which is used in conventional solar cells – polymers and a molecule called fullerene are deployed here to generate electricity from solar energy. The two components are mixed and printed onto substrates, just like letters on paper. Like a second skin, they can even be applied to curved surfaces. Studies have shown that the production of organic solar cells is more than 90 per cent more eco-friendly than that of conventional solar cells if different environmental impacts such as energy expenditure, toxicity or resource consumption of metals are considered. In addition, the electricity generated by OPV panels is up to 88 per cent more eco-friendly than electricity from conventional solar cells. [3]

A complete OPV module looks like plastic, is lightweight, flexible and transparent. It can be integrated into roofs, facades, glass, bus stops and other surfaces. Wherever energy is needed, the new technology can convert solar power into electricity. The panels come in various shapes and designs, so that they can be integrated into architectural designs as desired. Two examples from real life:

Example 1: Harvesting energy from the solar tree

Artificial, twelve-metre-high plants exhibited at the 2015 World Expo in Milan demonstrated what organic photovoltaics can offer modern architecture. The solar trees provide shade and produce electricity at the same time. Their solar cells close the calyx like a lid, and a narrow strip of organic photovoltaics extends to the bottom of the stem.

The solar trees were developed in close cooperation with several companies: the photovoltaic manufacturer OPVIUS, the pharmaceutical and chemical group Merck, the provider of architectural solutions Carl Stahl, the provider of electro-technical installations the Hager Group, as well as Schmidhuber Architekten and the cable manufacturer U.I. Lapp. Germany’s Federal Ministry of Education and Research supported the project too. Following the world exhibition, the developers wanted to find a new use for the solar trees. So they ended up being adapted to Germany’s weather conditions, which, for example, include higher snow loads. Today they are standing in the redesigned entrance area of the Merck Group’s company headquarters in Darmstadt [4].

Example 2: Large-scale use of organic solar cells

In Rio de Janeiro, visitors can charge their smartphones on the forecourt of the Museo do Amanha – with electricity produced on site by the “OPTree” created by manufacturer Sunew. The company’s OPV panels are also suited for large-scale use in glass facades. At the corporate headquarters of the software company TOTVS in Sao Paulo, for instance, more than 200 square metres of laminated glass have been equipped with Sunew’s sustainable technology. The semi-transparent panels not only generate electricity, but also provide shade for the interior spaces.