What does Perc

PERC solar cells without loss of efficiency

The joint project “Zero Degradation in Mono- and Multi-Crystalline PERC Solar Cells (Zorro)” funded by the BMWi is coordinated by the Fraunhofer Institute for Integrated Systems and Device Technology IISB in Erlangen.

Renewable energies are an integral part of the energy mix today. The use of sunlight by photovoltaic solar modules plays a pioneering role. Here the crystalline Silicon technology a share of approx. 95% in the world photovoltaic market.

High susceptibility to degradation

With the development of the so-called PERC (Passivated Emitter and Rear Contact)-Solar cells, the cell efficiency could be increased again significantly in the last few years. They are currently over 22% for monocrystalline and around 20% for multicrystalline silicon base material.

The problem: The PERC solar cells are very susceptible to degradation, i. H. the The efficiency of the solar cell can drop by several percentage points during operation. One of the reasons for this loss of efficiency is lighting at elevated temperatures, the so-called LeTID (Light and Elevated Temperature Induced Degradation) phenomenon. The mechanism of action and the cause of the LeTID phenomenon are currently not sufficiently understood.

Understanding the process dependency

As part of the Zorro joint project, a Zero degradation concept for the industrial production technology of multi- and monocrystalline PERC solar modules Developed. Basic studies should initially enable a comprehensive, in-depth understanding of the process and material dependency of LeTID and related degradation effects in mono- and multicrystalline PERC solar cells.

The cause of the degradation that occurs is on the one hand sought in the mono- and multicrystalline wafer material produced. On the other hand, individual steps in solar cell processing are analyzed in detail and the partial results are ultimately linked in a targeted manner. The focus is on that Interplay of a wide variety of pollution elements in the wafer base material with hydrogen, which is introduced during the production of the solar cell in the surface passivation step.

Amalgamation of numerous competencies

The Zorro project consortium consists of one Merger of four research institutions and two associated industrial partners. The Fraunhofer IISB from Erlangen, which coordinates the project, contributes its expertise in the field of crystal growth and takes on the production of specifically contaminated silicon base material.

The International Solar Energy Research Center Konstanz e. V. (ISC) is responsible for the production of PERC solar cells. The defect and degradation tests are carried out by the University of Konstanz (UKN) and the Institute for Applied Physics (IAP) at the Technical University of Freiberg (Saxony). Wacker Chemie AG and centrotherm international AG are involved in the Zorro project as associated industrial partners.