The translucent, coloured cells will form a 300m2 façade, resembling a stained-glass window. EPFL is cautious as to the performance of the cells, a nascent technology compared with silicon photovoltaic cells. They anticipate 8,000kWh of electricity a year, a tiny portion of the Center’s total energy consumption. However, they will also prevent the huge atrium from turning into an unbearable suntrap.
The cells are being developed by local firm Solaronix at a rate of around 30 modules a day, and looking for further investment to increase production capacity. That won’t be easy, as Professor Michael Grätzel, who made initial DSC discoveries at the EPFL over 20 years ago, explains: “Falling subsidies, overcapacity and resulting bankruptcies witnessed by the conventional silicon photovoltaic (PV) industry has made it challenging for DSC developers to get the funding they need.”
Meanwhile, improvements in efficiencies, lifetimes and stability – by the EPFL and others globally – continue to increase the suitability of DSC for real-world applications. Also known as ‘Grätzel cells’, they have some advantages over silicon PV. One is the ability to generate electricity at low irradiance: indoors, under fluorescent tube lamps, they have achieved 26% efficiencies, compared with 9% for silicon. They also require less resource and energy-intensive production processes, and payback for a 7% efficiency DSC module is roughly three months, compared to two years for silicon.
Efforts to commercialise DSCs are building. Welsh manufacturer G24I Power began supplying flexible DSC modules to Swiss company Logitech in late 2011 for integration into a self-powered iPad keyboard accessory. Swedish DSC developer Exeger has its sights on three market opportunities for DSC: consumer electronics, indoor applications and building-integrated PV (BIPV). The company recently secured $20 million in funding to make transparent DSCs in a range of colours on flexible and glass substrates using screen-printing techniques.
Exeger CEO and founder Giovanni Fili expects to see DSCs take off in consumer electronics before they reach scale in construction. “They are great for meeting growing demand for wireless power”, he explains, “because they do not obscure, change or dilute the value of product design.”