The solar cells that can power buildings

Heliatek is one of the World Economic Forum’s 2015 class of Technology Pioneers. Its organic solar film is light, flexible, transparent and less than a millimetre thick. The company’s CEO, Thibaud Le Séguillon, explains how it is enabling buildings and vehicles to generate their own electricity.

How do organic solar cells differ from traditional photovoltaic panels?

Two behaviours make organic solar cells different. First, traditional solar panels become less efficient in hot weather, which is an unfortunate paradox given that sunny days tend to also be hot. In contrast, organic solar cells perform better the hotter it is. Second, traditional solar panels experience a sharp drop-off in performance in low-light conditions. Organic solar cells can cope better with cloudy days and can even generate significant power indoors from artificial light.

The solar film we produce, HeliaFilm^®, is very thin, light and flexible. It can be made transparent with a tint, like sunglasses, in various colours. HeliaFilm^® can go in many places where traditional photovoltaic panels would be too bulky, such as on vehicles and the facades of buildings rather than just the roof.

Who else is working on organic solar cells and how does Heliatek’s approach differ?

There are a few other companies working on this, but we are recognized as the leader in the field for a couple of reasons. We hold the world record in efficiency for organic solar cells, currently at 12%, and we are also the only company currently manufacturing at scale.

There are two ways to make organic solar cells. One is to print a long chain of polymers, and the other – which is our approach – is to use much smaller molecules, oligomers, which we vacuum-deposit without needing to use solvents. We develop our own molecules here in our laboratories, which means we effectively control our own raw materials and we are able to work constantly on improvements; rather like a pharmaceutical company, we are experimenting with creating new molecules all the time.

How quickly has the technology advanced, and what future progress do you expect?

When we started in 2006 (the company is a spin-off from the Technical University of Dresden and the University of Ulmas), our efficiency was less than 3%. We think it is feasible to hope for 20% by 2020 and 25% by 2025, though it’s hard to predict exactly what path might take us there.

Alongside increasing efficiency, lifespan has been one of the greater challenges. The molecules themselves need to be very stable and they need to be encapsulated in a protective layer, both tasks on which we have worked hard. We currently warranty for 10 years, and next year we will be upping that to 20 years.

We’ll also be looking to develop the product in ways such as making it completely transparent, rather than tinted, to widen the range of possible applications on windows. In effect, this means we will have to harvest only non-visible light – ultra-violet and infra-red. We know how to do this in principle, but just need to devote the resources to developing the molecules.

To put the current 12% efficiency figure in perspective, how much electricity could HeliaFilm^® generate if you covered a building in it?

Take a representative example of our first target markets – an average industrial building in Italy of, say, 30,000 square metres. If you cover it with HeliaFilm^®, you can meet about 40% of its energy requirements.

Is HeliaFilm^® more suitable for new builds or can it be retrofitted into existing structures?

Initially new buildings are more suitable, as planning from the design phase makes it easier to integrate needs such as cabling. We are currently working with manufacturers of glass, concrete and steel to integrate our product in the products they sell to the construction industry.

Further down the road, we can also envisage developing products more suited to retrofit projects, and eventually even ones you’ll be able to buy in a local home improvement store.

And what are the opportunities in transport?

We’re currently working with car manufacturers to integrate HeliaFilm^® into their design, and we anticipate that refrigerated trailers will also be a big market for us. We don’t think we’ll be able to supply all the power they need, but we can make a major contribution.

Is there a role for public policy to speed the adoption of products like HeliaFilm^®?

Yes, in two ways. One of the reasons car manufacturers are coming to us is that in both the United States and Europe, regulations are setting increasingly stringent targets to lower CO₂ emissions per kilometre. And one way the manufacturers can do that is by using a product like HeliaFilm^® to contribute to generating the power the car needs.

Governments can also help through building codes, by making it mandatory that all new buildings should be net zero energy. There is a European Union directive in the works along these lines. This will go beyond making sure the construction industry does everything it can to improve insulation and energy conservation, and push them towards making buildings also produce energy. The construction industry is very conservative by nature, so any push we can get from regulators will speed up the pace of market acceptance.

Where do you see the technology ending up in the longer term?

When you build with HeliaFilm^®, you are turning your building into a power station. We see this ultimately changing the way society thinks about energy generation. Instead of being something we do in a centralized way, whether through gas-fired or coal-fired power stations or solar or large-scale wind farms, we will see it as normal for energy to be generated more locally.

The market is huge – not only vehicles and buildings, but pretty much anywhere you can imagine wanting to produce energy locally: mobile devices, clothes, your imagination is the limit. Indeed, I know that I don’t have enough imagination to foresee today where the product will be able to go. I am sure it will surprise us.

Full details on all of the Technology Pioneers 2015 can be found here. 

Author: Thibaud Le Séguillon, CEO, Heliatek, a World Economic Forum Technology Pioneer.

Image: The sun is reflected in the new European Central bank headquarters during its partial eclipse in Frankfurt, March 20, 2015. REUTERS/Kai Pfaffenbach