Solar energy: how can existing infrastructure be used more efficiently?

Photovoltaics have long generated a buzz – you can find them on the roofs of many homes, in vast solar parks, and even swimming on the surface of water. But in addition to plenty of sunshine, these renewable-energy technologies require a great deal of space. Innovative ideas are emerging to circumvent this issue.

The Institute for Advanced Sustainability Studies (IASS) has come to the conclusion that powering Europe with electricity from 100 percent renewables would require a dedicated area of some 97,000 km2. That’s roughly the size of Portugal. And, as critics have noted, solar farms on this scale present problems. They not only change the landscape – they also occupy valuable space that could be put to other uses.

So how can we enjoy the advantages of photovoltaics, without taking up so much habitat? One way is, quite simply, making more efficient use of existing infrastructure. For example, in Belgium in 2011, 16,000 solar panels were installed on the 50,000 m2 roof of a 3.4 km railway tunnel – generating around 3,300 megawatt-hours of electricity per year.

And now, the Fraunhofer Institute for Solar Energy Systems ISE is joining forces with the Austrian Institute for Technology for a much larger project: a gigantic roof of solar panels over freeways. The international team of researchers is currently developing a prototype; once completed, it will be subjected to a year of extensive testing. As Fraunhofer’s Dr. Martin Heinrich explained to German digital news source FOCUS online*:

“On the whole, I think it makes absolute sense to use streets as a space for generating electricity, through noise control barriers, street integration or roofing, for instance. That can be combined with other resources, for example on agricultural land.”

Sunny side up

Swiss start-up dhp Technology is already a step ahead. It has developed a folding solar roof for the dual use of existing infrastructure – parking spaces, water treatment plants, warehouses and distribution centers, to name a few – without negatively impacting their original purpose. Since July, the lightweight plastic modules, at a lofty height of six meters, have spanned an approximately 4,000 m2 parking lot in the canton of Appenzell. They are expected to produce around 350,000 kilowatt-hours of electricity annually. The spacious design of the structure allows large trucks to easily navigate around the slender supports. However, when strong winds or heavy snows threaten, the roof has to be folded back accordion-style and safely stowed.

Folding solar roofs offer a further advantage, particularly at the height of summer: they provide shade for vehicles parked below, and ensure the asphalt absorbs less heat. “Especially in urban areas, these types of structures help to make hot summers more bearable,” underscores Gian Andri Diem, one of the managing partners of dhp Technology, in conversation with Swiss newspaper Neue Zürcher Zeitung.*

*Available in German only