Solar

BP Solar Seeks Ribbon-style PV Manufacturing Approach

Echoing the direction of some rival solar companies, BP Solar is hoping to harness its own version of a ribbon-based approach to the manufacturing solar photovoltaic (PV) cells.

The Faculty of Sciences of the University of Lisbon (FCUL) and BP Solar have announced a research agreement with the aim to develop a new manufacturing technology with the potential to reduce the cost of solar cells. A significant obstacle to the expansion and wide scale production of solar electricity remains the high cost of solar cells, more than half of this cost is associated with the price of silicon wafers, (high-purity silicon crystals). Traditionally, the thin (0.2 mm) silicon wafers that are used to manufacture silicon solar cells are produced by slicing large high-purity silicon ingots. This process wastes more than half of the original material since the wire that is used to saw the ingot into wafers has a thickness similar to that of the finished wafers. In order to avoid material wastage and to reduce costs, an alternative is to seek new methods for the growth of silicon crystals directly in the form of a ribbon. Though a simple idea first proposed more than 40 years ago, the production of good quality silicon ribbon at low cost has proved an “extremely difficult problem,” according to a BP Solar statement on the partnership. Despite this statement, it should be noted that other solar companies have achieved commercial success with ribbon-style manufacturing, Evergreen Solar being the leading example. The Group of Semiconductors and PV Applications of FCUL has dedicated much of the last decade researching alternative techniques for the growth of silicon ribbons. This research lead recently to very interesting results with a new technique, which has been filed for an international patent. This new technique, called EZ-Ribbon, is based on a physical process with potential for a significant reduction of the cost of the solar cells, according to BP Solar. Recognizing the potential interest of this new technology, BP Solar has decided to finance its development with a Euro 600,000 [US$ 753,000] three-year research project as part of the BP Solar Future Technology activity. The Portuguese Foundation for Science and Technology is also supporting this project.