The Swiss National Science Foundation boosts renewables research

© Alain Herzog – EPFL 2015

© Alain Herzog – EPFL 2015

Fifteen joint research projects have received funding to prepare Switzerland’s energy transition. Two of them focusing on photovoltaic energy and its architectural integration, will be led by EPFL.

Switzerland has launched a broad-ranging national research program on the energy transition (NRP70). Two researchers from EPFL will be heading two joint research projects. Christophe Ballif, from EPFL's PV-Lab will direct PV2050, which aims to improve photovoltaic technologies and transfer them to the construction industry. Emmanuel Rey, from the Laboratory of Architecture and Sustainable Technologies (LAST), will direct Active Interfaces, which will identify and solve problems related to the integration of photovoltaic systems into buildings. Combining two complementary perspectives, the two projects will bring together developers, engineers, architects, and end-users.

We met with the two researchers to discuss what lies ahead.

Together, you are responsible for a large portion of the new national research program. What are your objectives?

Christophe Ballif: The main objective of this program is to develop tomorrow’s solar cell technology. We’ve seen dramatic progress in this field, but we would like to continue pushing the envelope. First, we aim to increase the efficiency of solar panels: we would like to develop a new class of devices that can reach 30% efficiency. Today the limit is close to 25% for terrestrial setups. This will be particularly interesting in Switzerland, as it is a small country and a large portion of its roofs would have to be covered to supply only one fifth of its electricity needs. But the higher the efficiency of the solar panels, the smaller the surface needed. As part of this aim, we will also assess the impact of these future technologies on domestic power production. The second objective will be to incorporate new photovoltaic technologies into the façades of buildings, which would increase the available area.

Emmanuel Rey: Only a small fraction of photovoltaic potential is currently being exploited in today’s buildings, and we cannot take successful implementation of photovoltaic technologies as a given. Our first mission will be to understand the obstacles and bottlenecks in the way of their integration into buildings. There is a gap between end-user demand and available products, as well as other considerable challenges in terms of their architectural integration.

To what extent can we improve existing buildings?

ER: One of our goals is, in fact, to better integrate photovoltaic panels in urban renewal projects. Many of today’s buildings will be renovated in the coming decades, and we have to make these renovations coincide with the energy transition. Design and technology have to be closely linked and coupled with social and cultural considerations to ensure that projects incorporate solar technologies harmoniously. This is still largely absent today.

You plan on working together closely to combine your expertise in technological development and architectural integration. What do you expect to gain from such a multidisciplinary partnership?

CB: We engineers and manufacturers have made tremendous progress in terms of the fabrication of solar panels and their cost, which is why we are often frustrated by the fact that they are not used more often by architects. We have concluded that our contribution – providing the actual technology – has not been enough for the wider public. There are economic parameters and social parameters that continue to evade us; unless my neighbor has a solar installation, I won’t think about getting one myself. This leads to a vicious cycle: we have to increase production and installation of quality photovoltaic systems in order to reduce their cost. But people have to first be aware of the technology itself before we can increase its production.

ER: By adopting an interdisciplinary and coordinated approach between engineers and architects, we bring together elements from both worlds. One is predominantly focused on efficiency, the other on aesthetics and integration. If we include these new technologies early on, we can transform the project into a form of “raw material” that can help the architecture evolve. The premise is no longer to just attach a solar panel onto a building’s façade; instead, a photovoltaic panel could replace an entire element of it. This qualitative and quantitative challenge forces us to work more closely together as designers and technological experts.

What can be done to further increase the efficiency?

CB: We hope to develop new setups with improved efficiencies by adopting new approaches – specifically, stacking multiple layers of solar cells, each able to absorb a different part of the solar light spectrum. This requires coupling together completely flawless components for which we have yet to develop compatible production procedures. Each layer can also be sensitive to temperature, humidity, or structural flaws, so we are up against a considerable challenge.

But it seems that are other aspects that have to be improved as well to continue to develop the industry…

CB: The potential of photovoltaic technologies is immense. But because their energy production is intermittent, managing it leads, in the short term, to a number of problems that can be overcome by adopting smart grids, dams, or local storage solutions. Then there is the challenge posed by the seasons. But drops in energy production during winter could be mitigated by integrating solar panels directly into building façades. In this case, electricity could still be generated at the levels of the summer months.

ER: The challenge is to speed up the transfer of academic research to the people implementing the technologies on the actual construction site. We are planning to model actual projects and submit them to those interested for evaluation. We would like to forge ties between various disciplines to grow a new culture in Switzerland. Getting there will require improving the aesthetic integration of projects and developing the best designs for each element. Today, the technology provides us with panels in a wide range of colors, including white. To meet our objectives, we will have to work on color options, but also on finishing elements, construction details, the size of the modules, and even the texture of the solar panels.

What are the limits of solar power or the technical, social, cultural, or economic challenges that will have to be met?

ER: Simply installing solar panels on rooftops can lead to blockages, particularly from municipalities that are, rightly, afraid that their townscapes would be defaced. Integration is therefore essential. That is why our ambition is to develop new paths to achieve both qualitative and quantitative improvements, without losing the identity of our cities.

CB: Communication between engineers and the other construction-related professionals sometimes just doesn’t exist. Let me cite an example of this that I experienced myself, where we had to remove the all the gravel from a brand-new rooftop just to set up the support structure for solar panels, simply because there had not been enough coordination or effort into the integration during the early stages of the project. Generally, I think that people are still reluctant, for all kinds of reasons – good and bad. But the change will come; buildings with lower energy requirements will all have photovoltaic setups. In the Canton of Vaud, all new buildings are by law required to produce some of the power their residents will consume. So now, all of the trades involved in construction will have to face up to this reality.

Authors: Sandy Evangelista, Jan Overney