Driving solar cell module cost towards 1 Euro/Watt-peak
Joachim John, teamleider industriële zonnecellen Imec
The cost of silicium constitutes about one third of the solar cell module cost. In order to be less dependent on price fluctuations of polysilicon feedstock and wafers, and to eventually realize cost targets below 1 euro/Watt-peak, an evolution towards a reduction of ‘grams of pure Si/Wp’ is taking place. As one does not want to sacrifice solar cell efficiency despite the use of thinner wafers, this requires quite drastic changes for crystalline Si solar cell technology. As a basic trend one could state that the objective is to go for a reduction by a factor of two of the numbers of gram Si/Wp with an efficiency increase of roughly 25 percent relative.
The cost of crystalline Si is not the only part of the cost to be reduced. In the field of metallization drastic changes are foreseen. Replacing Al pastes by lower cost options or the replacement of Ag contacts are important. The latter is crucial in the long run as one will face sustainability issues with Ag when the PV market reaches sizes in the order of several tens of GWp/year.
These material developments have to go hand in hand with a reduction of the manufacturing costs. Crucial factors here are wafer size scaling, equipment scaling and increase of areal throughput and fab scaling from the present 50 MW/year to 1 GW/year. Vertical integration upstream (polysilicon feedstock production, crystallization and wafering) as well as downstream (modules, integration of invertor in the module) are required on the longer term to drive down costs to the desired levels of grid parity and below.
Biografie
Joachim John received his diploma degree in physics at the Albert-Ludwigs-University in Freiburg, Germany, in 1993 and his PhD in physics at the Federal Institute of Technology (ETH) in Zürich, Switzerland, in 1997. From 1990 to 1993 he was employed by the Fraunhofer Institute for Physical Measurement Techniques in Freiburg, doing research and development on semiconductor mid-infrared laser. From 1993 to 1998 he worked on the development of photovoltaic mid-IR sensor arrays at the ETH. In 1998 he joined Imec in Leuven, Belgium, where he is presently leader of the industrial solar cell team.