At the European Photovoltaic Solar Energy Conference and Exhibition that took place in Frankfurt between 24th and 28th of September, Professor Christophe Ballif and his team of researchers from the Photovoltaics Laboratory (PVlab)- EPFL’s Institute of Microengineering in Neuchatel, presented a striking innovation. They claimed that as little as $2500 in photovoltaic cells could easily serve the electricity needs of a four people household.
For the past few years, the team has been heavily involved in developing the so-called ‘heterojunction technologies’ in order to optimize solar captors’ performance. This is done by applying microscopic layer of amorphous silicon on each side of a crystalline silicon wafer. According to Professor Ballif, this is what increases the sensor’s efficiency.
Antoine Descoeudres, Stephaan DeWolf and their colleagues came up with the most effective way to enhance the performance of the amorphous silicon interface, by improving the process of application using crystalline cells (called “p-doped silicon”). They estimated a conversion efficiency of 21.4%, which, compared with the highest measured one of 18-19% obtained by monocrystalline cells, sets a record. However, this is not the only achievement. They managed to obtain an open-circuit voltage of 726mV and break the efficiency barrier of 22% on a less common substrate.
Commercializing these newly developed sensors should not take long. The Swiss company Meyer Burger is already marketing machines that assemble the hybrid technology. Stephaan DeWolf is confident that within five years the production cost will be around $100 per square meter of sensors, while such surface will be producing up to 300kWh of electricity per year in Switzerland.
The results are expected to appear in the IEEE Journal of Photovoltaics later this year.