Comparison of heat losses model of a number state-of-the-art chemical vapor deposition (CVD) reactors for solar grade silicon (SoGSi) production for the photovoltaic’s industry.

Project facts

Project promoter:
POLYTECHNIC UNIVERSITY OF MADRID
Project Number:
ES07-0036
Target groups
Researchers or scientists
Status:
Completed
Initial project cost:
€8,900
Final project cost:
€8,900
From EEA Grants:
€ 8,900
The project is carried out in:
Spain

Description

There is a debate in the polysilicon community about the benefits and drawbacks of different deposition technologies, but there is a lack of reliable data. The partnership collaboration will contribute to that debate developing a model of heat losses of a state-of-the-art fluidized bed reactor (FBR) for SoGSi production. This model will be compared with an already developed model for heat losses in a Siemens CVD reactor and the influence of a number of overall design parameters on the energy consumption will be studied. The partnership will achieve further knowledge of the CVD processes for SoGSI production; a novel model for heat losses of a FBR is going to be development and recommendations will follow to reduce the heat loss in the reactors made the limited in energy savings calculated. Both institutions have many years of experience on the field of silicon based photovoltaic technology and have exchanged their knowledge in through presentations and discussions at a number of international conferences in the past. Further, parallel to this project there is cooperation in the framework of the European Energy Research Alliance.

Summary of project results

For an installed silicon based solar cell, silicon feedstock is responsible of about 40% of the energy consumed in the whole production chain. Reducing the energy consumption in this step is crucial. Main alternative to the CVD convectional method, in particular the so-called Siemens process, is the Fluidized Bed Reactors (FRB). These reactors use silane as precursor gas leading to lower process temperatures and lower energy consumption at the expense of the resulted material quality. There is a debate in the polysilicon community about the benefits and drawbacks of different deposition technologies, but there is a lack of reliable data. The project has developed a theoretical heat loss model for a FRB, allowing, further than an energy consumption comparison with the CVD convectional method, a sensitivity analysis of the FRB design parameter. In the project, the process of conversion of silane gas to solid polysilicon focusing on the energy consumption and heat loss has been investigated. Computational fluid dynamics models (CFD) have been developed and results obtained with them and data obtained experimentally have been compared. The model developed for a Siemens laboratory scale reactor has been found good enough to reproduce the polysilicon deposition process conditions; the model for the FRB prototype provides reasonable estimates of the temperatures distribution. The actual possibilities of changing the relevant parameters to address the current limitations of both processes have been discussed. This made possible a discussion on material quality, and how project findings are related to it. A paper to be sent to a peer reviewed international journal is in preparation. The Autonomous University of Madrid is interested in exposing the results of the project in the frame of the Master on Advanced Materials. Partner institutions have shown their interest in future collaborations, in particular in the frame of Horizon2020.

Summary of bilateral results

This Project results will be translated in further knowledge of the CVD processes for SoGSi production, field in which both institution have been focusing their research during several years. Until now, the Institute for Solar Energy (Spain) have been focusing its efforts on the Siemens process while at the Institute For Energy (Norway) reach have been focused on FBR. Thereby, the exchange of knowledge acquired so far at both institutions will encourage the future work on both research Iines. Comparison between model results for different state-of-the-art CVD technologies for SoGSi Production will follow up and update previous studies. The results of the comparison will be published in a joint publication between both partners, submitted to a peer-reviewed journal during or shortly after the end of the project period. In addition, both institutions share other research topic in the field of silicon basic Photovoltaic technology that could be susceptible for further cooperation. The Autonomous University of Madrid is interested in exposing the results of the project in the frame of the Master on Advanced Materials. Partner institutions have shown their interest in future collaborations, in particular in the frame of Horizon2020. Further, parallel to this project there is cooperation in the framework of the European Energy Research Alliance.