Thin Ribbon Technology Will Cut Silicon Requirements to 33% of Industry Norm; Competitive Advantages are Increased by Tightening Supply of Solar-Grade Silicon

MARLBORO, Mass.--(BUSINESS WIRE)--Dec. 7, 2004-- Evergreen Solar, Inc. (Nasdaq: ESLR), a manufacturer of solar power products with proprietary, low-cost manufacturing technology, today announced a major advance in the development of its String Ribbon(TM) manufacturing process that has the potential to produce silicon wafers thinner than 150 microns. The Company has filed a patent application for its thin wafer technology.

"Evergreen Solar's mission since its inception has been to produce high-quality solar products at a fraction of the cost of conventional methods," said Richard M. Feldt, President and Chief Executive Officer. "Today we are announcing an important step in realizing that goal. With the latest enhancement to our Gemini II double ribbon growth process, Evergreen Solar has demonstrated in its pilot operations that it can manufacture wafers using one third of the silicon required by conventional methods - significantly reducing the overall cost of producing solar panels. The ability to produce the thinnest wafers in the solar industry affords our Company with a decided competitive advantage that no other company has demonstrated. This breakthrough demonstrates the robustness of our String Ribbon manufacturing process."

"By changing the growing conditions in our Gemini II furnaces, we can produce wafers that are half the thickness of our current standard," said Dr. Brown F. Williams, Vice President, Research and Development. "This achievement directly cuts the use of silicon in half for us and by a factor of three when compared to conventional methods."

"Our competitors produce wafers by sawing slices of silicon off of large ingots. The silicon lost in the width of the saw cut means that other wafer manufacturers are effectively throwing away half of their silicon starting material. Our standard String Ribbon process already avoids that shrinkage. Moreover, because current cutting techniques have difficulty producing wafers as thin as 150 microns, we truly have a unique, defensible competitive advantage," Williams added.

Feldt said, "There is some concern that the tightening silicon supplies may limit the growth of the photovoltaic industry for the next year or two. Our technology's potential to further reduce silicon requirements is really quite dramatic and holds great promise for our industry. We expect that production of our thin wafers will entail other savings in material costs and the thin wafers will perform at a higher level of efficiency."

"The yield from the pilot quantities of our thin wafers processed into solar cells and assembled into complete panels has been encouraging. As a result, we will methodically scale our pilot operations and debug our wafer, cell and panel manufacturing processes for thin ribbons. Based on our preliminary work to date, we would expect to be able to achieve production status by the end of 2005. Additionally, we expect this breakthrough should position us even more favorably with potential partners as we proceed with planning for our next commercial expansion," Feldt concluded.

About Evergreen Solar, Inc.

Evergreen Solar, Inc. (Nasdaq: ESLR) develops, manufactures and markets solar power products utilizing the Company's proprietary low-cost manufacturing technologies. The products provide reliable and environmentally clean electric power in global markets. Solar power applications include complete power systems for electric utility customers choosing to generate their own environmentally benign power, as well as wireless power for remote homes, water pumping, lighting and rural electrification. For more information visit www.evergreensolar.com.