Flexcell transfers the sun’s energy to a flexible surface

Alexandre Closset, CEO of VHF-Technologies SA, talks to e-tech's Flip Martin-King.

This article originally appeared in the August 2007 issue of IEC e-tech.

The answer lies with Alexandre Closset, the chief executive officer of Flexcell, a state-of-the-arts Swiss company that produces flexible photovoltaic elements.

Alexandre Closset: I studied physics at the EPFL (the Swiss Federal Institute of Technology in Lausanne) and then worked for a further two years there as assistant in the field of fuel cells in the department of chemistry. That’s how HTceramix (Solid Oxide Fuel Cells) came about (Editor’s note: see the April edition of e-tech). After leaving the EPFL, I went on to work for a year with Norsk Hydro in Norway where they were setting up a test measurement project. Following that, I did an Executive MBA in Management of Technology in Lausanne (MoT). That’s when I met Diego Fisher who had been working on solar cells for his PhD at the Institute of Microtechnology in Neuchâtel (IMT). Together we drew up the business plan for our renewable energies start-up companies which we set up in 2000. Today, he’s the Technical Director of VHF-Technologies.

You ask what our PV (photovoltaics) business has to do with a large multinational, leader in the food and beverage industry? That’s the third link and where Enrico Tagliaferri comes in. Originally he was doing research at Nestlé’s research centre. He later proved to be innovative in devising our “lift-off equipment”, the machine we’re still using today to wash the plastic substrate after the deposition of a thin metal layer. It just goes to show that carrying out studies in the world of enzymes and vitamins in milk can have broader implications than one might first imagine.

e-tech:
According to Solarbuzz, worldwide photovoltaic installations increased by 1 744 MW in 2006, up from 1 460 MW installed during the previous year. By comparison, in 1985, annual solar installation demand was only 21 Megawatts. And, if the earth receives more energy from the sun in just one hour than the world uses in a whole year, there are two billion people in the world who have no access to electricity and yet they can’t afford solar photovoltaics, although it would be their cheapest source of electricity.

e-tech: As for other energy statistics?
Alexandre Closset: The IEA (International Energy Agency) Photovoltaic Power Systems Programme has figures that show that there is already a growth capacity potential in Europe, Australia, the USA and Canada of 23 billion square meters of existing roof space for PV. Now if you take an efficiency figure of 5% of the irradiance converted into electricity, that represents an installed power potential of 1 000 GW and sufficient to replace several nuclear power stations. The potential is there. For example, in German Bavaria which is not exactly a tropical area of the planet, they are already covering 1% of their total electricity needs using photovoltaic energy. There are laws in place that ensure that electricity companies buy back the solar power that’s generated and encouragement programmes for industry to install photovoltaic panels. Over a period of five years, Germany has created over 100 000 jobs in the area of PV.

e-tech: And the environmental consequences?
Alexandre Closset: In the process of converting sunlight into electricity, there are no moving parts, so there are minimal maintenance costs, and no emissions or noise. The material used for our elements is essentially silicon which is non-polluting, and plastic which is easily recyclable.

e-tech: What is particular about your photovoltaic cells?
Alexandre Closset: We use proprietary very-high-frequency plasma technology to deposit thin consecutive layers of amorphous silicon onto light plastic substrates. When I say plastic, I mean that we’re able to use extremely thin sheets (50 microns) as the basis for our photovoltaic cells. That allows us to provide solutions such as rollup battery chargers, like those that the South African explorer and extreme athlete, Mike Horn, has taken with him in his backpack to Pakistan where he doesn’t have space for heavy and cumbersome material in his latest Himalayan expedition: four 8 000 metre summit climbs without oxygen that he’s undertaking with mountaineers Jean Troillet, Fred Roux and Olivier Roduit. Our 13.5 Watt, 15 volt charger is sufficient to enable him to run any 12 volt electronic system and keep in touch with the world. Indeed, Mike aims to be the first ever adventurer to broadcast live over the Internet from the top of the world.

e-tech: Are there any other more every-day uses?
Alexandre Closset: On a less adventurous, but more general public level, we supply innovative integration solutions for OEM applications such as those used in emergency and stand-alone systems. For example, the TGV (high speed train) from Paris to Strasbourg in France had a problem with the glass solar panels they’d erected along their railway line because the stones kept on shattering them. Since it’s not feasible to link up the emergency phones to the same electricity grid as the train, they needed another solution. A flexible plastic substrate such as ours was perfect. It’s practically unbreakable and customizable according to need.

Another example is that used in the city of Lausanne. They’ve integrated photovoltaic sheets into the pull-down sun awnings on the balcony of an apartment. So, not only are they protecting the apartment from the sun, but, at the same time, they’re generating green energy.

e-tech: What about building applications?
Alexandre Closset: We’re working with building component manufacturers to develop other applications of BIPV (building integrated photovoltaics) as this type of foil-based approach means that you can adapt PV to all sorts of surfaces: rooftops, walls and so on.

Because the substrate is so light and supple, you don’t have the problem of rigidity and weight normally associated with traditional solar panels. If you look at our local skating rink, you’ll see that the slope and curve of the roof there didn’t stop them integrating a series of PV modules. We simply adapted the sheets to the shape of the roof tiles and they didn’t have to make any changes to the original building.

e-tech: And quality. Are there any specific considerations you look at?
Alexandre Closset: Of course, there are stringent quality controls necessary. We can manufacturer a roll of 500 meters by 30 centimetres and that width is shortly to increase to 50 cm as soon as our new machine is ready for production. We need to be able to ensure that there is no loss of energy and that the modules will withstand rain, cold temperatures when it snows and, of course, the heat of the sun. Anyone investing in photovoltaics expects their panels to last for a good number of years to gain a return on their investment. The European Union requires a guarantee of 20 years for roofing which, in today’s consumer world, is a tremendously long time and even consumer products have a legal requirement to be guaranteed for two years.

So, we have several test machines set up here in Yverdon. For example we’ve been carrying out various assessments in our laboratory where we simulate extreme weather conditions. There are machines set up to test in relation to IEC 61646, Thin-film terrestrial photovoltaic (PV) modules – Design qualification and type approval parts:

• 10.11, Thermal cycling;
• 10.12, Humidity freeze and
• 10.13, Damp heat.

Our results show that despite the stress to which we’ve subjected our photovoltaic elements, we’re well within the levels specified by the IEC standards so there shouldn’t be any surprises when we come to pass the TÜV quality tests required by our German investors, Q-Cells. The advantage to having passed tests is that it will give us one more marketing argument to add when we talk to our clients.

Source: International Electrotechnical Commission (IEC).