Advanced processes using alternative raw materials for an economic production of high efficiency solar cells and modules. – PROTERRA

Abstract
In the very difficult context of today’s photovoltaic market, the competition is increasingly fierce and consequently a very sharp decline in the selling price of PV modules, especially those from China, is observed. The financial results of Photowatt in the fiscal year 2009 have been very mixed. This dangerous situation weakens and may even, in the medium term, threaten the French photovoltaic industry.
To deal with this situation, Photowatt has put all its efforts to improve its market share. To achieve this goal, Photowatt will increase research and development actions to go deeper into more advanced manufacturing processes. These processes will achieve the desired solar cell conversion efficiency that must remain among the best worldwide, with a sharp reduction in the consumption of silicon and other raw materials while meeting the legal requirements of environmental and trade standards. This can not be done without innovations adapted to today's technology, on which PHOTOWATT expects national partners (CEA / LITEN-INES, laboratories of the CNRS and French SME) early results across an R & DT national project named PROTERRA.
The main objective of this project is to reach within 3 years the innovative manufacturing processes, giving an increase of average conversion efficiency of cells and modules of an absolute point compared to the current industrial process. We aim conversion efficiency above 20% on crystalline silicon solar cells with a significant reduction in production cost in order to reduce module cost towards the goal of 1 Euro per watt-peak. The most sensible approach for this project is obviously to work simultaneously on 2 areas: Raw material cost and more efficient manufacturing processes.
To achieve the objectives of the project, a new cell structure, which has never been used in the French PV industry, will be developed. This structure has a stack of passivation and antireflection layers, a front grid contact with very fine lines formed above the heavily doped regions of passivable emitter, a passivated rear side by dielectric layers with located BSF and contact. Different approaches of thermal treatment will be used to achieve an excellent metallic contact quality using alternative materials and new concepts for the metallization.
This project will last 36 months and is divided into five technical areas:
- Selective removal / localized doping
- Advanced metallization
- Back side dielectric passivation
- Local BSF
- Efficient and recyclable modules.

To carry out these technical areas, a relevant and solid partnership has been established which brings together around PHOTOWATT, a photovoltaic manufacturer, laboratories of the CNRS (INL-INSA Lyon, IEMN) and CEA-LITEN who have revolved themselves since over twenty years designing and developing new photovoltaic cell concepts and a SME (TECHNIC IST) well known in the field of metallization for over 25 years.
The achievement of the goals of PROTERRA project will help reduce the cost of photovoltaic energy sources. The stakes are high as to create new employments and to preserve the jobs of 800 people within PHOTOWATT facility in Bourgoin-Jallieu. These actions will enable Photowatt to present on the market the modules of new generation with higher performances which significantly improves the competitiveness of the French PV industry. This will certainly increase the contributions of photovoltaic in renewable energy resources and to improve the sustainability of the national structure of energy supply.