Patents Assigned to Evergreen Solar Inc.
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Patent number: 8334453Abstract: A shaped tab conductor configured to allow more incident light to strike a cell substrate, improving the photovoltaic efficiency of the cell. The shaped tab conductor is configured to reduce the amount of incident light that is blocked by the tab from reaching the surface of the cell substrate. The tab may also be configured to redirect light reflected from the cell surface back to the cell surface. The cross-section of the tab conductor may be polygonal, such as a rhombus, with at least one generally planar surface that forms an acute angle with the substrate.Type: GrantFiled: December 10, 2008Date of Patent: December 18, 2012Assignee: Evergreen Solar, Inc.Inventor: Brown Williams
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Patent number: 8328932Abstract: A ribbon crystal pulling furnace has an interior for enclosing at least a portion of one or more ribbon crystals, and an afterheater positioned within the interior. The afterheater has at least one wall with one or more openings that facilitate control of the temperature profile within the furnace.Type: GrantFiled: June 13, 2008Date of Patent: December 11, 2012Assignee: Evergreen Solar, IncInventors: Weidong Huang, David Harvey, Scott Reitsma
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Publication number: 20120211917Abstract: A method of forming a sheet wafer 1) passes at least two filaments through a molten material to produce a partially formed sheet wafer, 2) directs a cooling fluid at a flow rate toward the partially formed sheet wafer to convectively cool a given portion of the partially formed sheet wafer, and 3) monitors the thickness of the given portion of the partially formed sheet wafer. To ensure appropriate thicknesses of the wafer, the method controls the flow rate of the cooling fluid as a function of the thickness of the given portion of the partially formed sheet wafer.Type: ApplicationFiled: February 23, 2011Publication date: August 23, 2012Applicant: EVERGREEN SOLAR, INC.Inventors: Leo van Glabbeek, Lianghong Liu, Weidong Huang, David Hitchcock, Stephen Yamartino
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Publication number: 20120164379Abstract: A sheet wafer has a generally flat, generally rectangular shaped body with a length and a width, and first and second filaments generally perpendicular to the width of the body. The first and second filaments are at least partially encapsulated by a wafer material and, together with the wafer material, form at least a portion of the body. The width is between about 145 mm and 165 mm.Type: ApplicationFiled: January 27, 2011Publication date: June 28, 2012Applicant: Evergreen Solar, Inc.Inventors: Steven Sherman, Leo van Glabbeek, Weidong Huang, Stephen Yamartino, Kaitlin Olsen
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Publication number: 20120125254Abstract: A method for reducing the range in resistivities of semiconductor crystalline sheets produced in a multi-lane growth furnace. A furnace for growing crystalline sheets is provided that includes a crucible with a material introduction region and a crystal growth region including a plurality of crystal sheet growth lanes. The crucible is configured to produce a generally one directional flow of material from the material introduction region toward the crystal sheet growth lane farthest from the material introduction region. Silicon doped with both a p-type dopant and an n-type dopant in greater than trace amounts is introduced into the material introduction region. The doped silicon forms a molten substance in the crucible called a melt. Crystalline sheets are formed from the melt at each growth lane in the crystal growth region. Co-doping the silicon feedstock can reduce the variation in resistivities among the crystalline sheets formed in each lane.Type: ApplicationFiled: November 23, 2010Publication date: May 24, 2012Applicant: EVERGREEN SOLAR, INC.Inventors: Brian D. Kernan, Gary J. Tarnowski, Weidong Huang, Scott Reitsma, Christine Richardson
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Publication number: 20110247546Abstract: A ribbon crystal has a body with a width dimension, and string embedded within the body. The string has a generally elongated cross-sectional shape. This cross-section (of the string) has a generally longitudinal axis that diverges with the width dimension of the ribbon crystal body.Type: ApplicationFiled: April 5, 2011Publication date: October 13, 2011Applicant: EVERGREEN SOLAR, INC.Inventors: Christine Richardson, Weidong Huang, Richard L. Wallace, Daniel Doble, Scott Reitsma
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Publication number: 20110155045Abstract: A sheet wafer growth system includes a crucible for containing molten material and an afterheater positioned above the crucible. The afterheater has an inner surface disposed toward the crucible. The system further includes one or more shields adjacent to the inner surface of the afterheater. The afterheater and the shield(s) are configured to allow a sheet wafer to pass adjacent to the shield(s). Each shield has two or more substantially different thermally conductive regions such that the two or more regions are configured to control the temperature profile of the growing sheet wafer.Type: ApplicationFiled: January 27, 2011Publication date: June 30, 2011Applicant: EVERGREEN SOLAR, INC.Inventors: Kaitlin Olsen, Weidong Huang, Christine Richardson
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Publication number: 20110023952Abstract: A photovoltaic cell has a semiconductor substrate formed from semiconductor material doped by a first dopant type, and a doped region over at least a portion of the substrate. The doped region is doped by a second dopant type that is opposite to that of the first dopant type to form an emitter. Moreover, the doped region is doped to a region dopant level. In addition to the substrate and emitter, the cell also has a plurality of semiconductor fingers formed on the emitter, a plurality of busbars formed from a conductor and intersecting the plurality of semiconductor fingers, and a plurality of tabs soldered to the busbars. The fingers are doped by the second dopant type to have a second dopant level, which is greater than the region dopant level.Type: ApplicationFiled: July 30, 2010Publication date: February 3, 2011Applicant: EVERGREEN SOLAR, INC.Inventors: Brown Williams, Christopher E. Dubé
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Patent number: 7842270Abstract: A string for use in a string ribbon crystal has a base portion with a refractory material, and an externally exposed layer radially outward of the refractory material. The base portion has a coefficient of thermal expansion that is generally matched with the coefficient of thermal expansion for silicon. The externally exposed layer has a contact angle with silicon of between about 15 and 120 degrees.Type: GrantFiled: December 9, 2009Date of Patent: November 30, 2010Assignee: Evergreen Solar, Inc.Inventors: Christine Richardson, Weidong Huang, Richard Wallace, Daniel Doble, Scott Reitsma
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Patent number: 7780782Abstract: A method of growing ribbon crystal provides a crucible containing molten material, and passes at least two strings through the molten material to produce a partially formed ribbon crystal. The method then directs a fluid to a given portion of the partially formed ribbon crystal to convectively cool the given portion.Type: GrantFiled: June 8, 2007Date of Patent: August 24, 2010Assignee: Evergreen Solar, Inc.Inventors: Weidong Huang, David Harvey, Richard Wallace, Scott Reitsma
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Patent number: 7718003Abstract: A method and apparatus for growing a crystalline or poly-crystalline body from a melt is described, wherein the melt is retained by capillary attachment to edge features of a mesa crucible. The boundary profile of the resulting melt surface results in an effect which induces a ribbon grown from the surface of the melt to grow as a flat body. Further, the size of the melt pool is substantially reduced by bringing these edges close to the ribbon, thereby reducing the materials cost and electric power cost associated with the process.Type: GrantFiled: November 26, 2007Date of Patent: May 18, 2010Assignee: Evergreen Solar, Inc.Inventor: Emanuel Michael Sachs
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Patent number: 7708829Abstract: A method and apparatus for growing a crystalline or poly-crystalline body from a melt is described, wherein the melt is retained by capillary attachment to edge features of a mesa crucible. The boundary profile of the resulting melt surface results in an effect which induces a ribbon grown from the surface of the melt to grow as a flat body. Further, the size of the melt pool is substantially reduced by bringing these edges close to the ribbon, thereby reducing the materials cost and electric power cost associated with the process.Type: GrantFiled: July 10, 2006Date of Patent: May 4, 2010Assignee: Evergreen Solar, Inc.Inventor: Emanuel Michael Sachs
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Publication number: 20100092776Abstract: A string for use in a string ribbon crystal has a base portion with a refractory material, and an externally exposed layer radially outward of the refractory material. The base portion has a coefficient of thermal expansion that is generally matched with the coefficient of thermal expansion for silicon. The externally exposed layer has a contact angle with silicon of between about 15 and 120 degrees.Type: ApplicationFiled: December 9, 2009Publication date: April 15, 2010Applicant: EVERGREEN SOLAR, INC.Inventors: Christine Richardson, Weidong Huang, Richard Wallace, Daniel Doble, Scott Reitsma
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Publication number: 20100055398Abstract: An apparatus for texturing two-sided wafers has a body capable of containing texturing chemistry (i.e., not necessarily containing the chemistry at this time), and a transport mechanism for transporting wafers through the texturing chemistry. The transport mechanism is configured to substantially wet no more than one side of wafers, transported through the body, with texturing chemistry.Type: ApplicationFiled: August 25, 2009Publication date: March 4, 2010Applicant: EVERGREEN SOLAR, INC.Inventors: Guenther Grupp Mueller, Brian McMullen
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Publication number: 20100055412Abstract: A method of forming a string for use in a string ribbon crystal provides a refractory metal as a core for the string and forms a first layer of material on the core. A method of growing a ribbon crystal provides a pair of strings. Each string has a refractory metal core. The method further passes the strings through a molten material to grow the ribbon crystal between the pair of strings. A ribbon crystal wafer includes a ribbon crystal material and a pair of strings in the ribbon crystal material. Each string defines an outer edge of the wafer, and each string includes a refractory metal core.Type: ApplicationFiled: September 3, 2009Publication date: March 4, 2010Applicant: EVERGREEN SOLAR, INC.Inventors: Christine Richardson, Lawrence Felton
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Patent number: 7651768Abstract: A string for use in a string ribbon crystal has a base portion with a refractory material, and an externally exposed layer radially outward of the refractory material. The base portion has a coefficient of thermal expansion that is generally matched with the coefficient of thermal expansion for silicon. The externally exposed layer has a contact angle with silicon of between about 15 and 120 degrees.Type: GrantFiled: August 29, 2008Date of Patent: January 26, 2010Assignee: Evergreen Solar, Inc.Inventors: Christine Richardson, Weidong Huang, Richard Wallace, Daniel Doble, Scott Reitsma
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Publication number: 20100000602Abstract: A photovoltaic cell has a photosensitive substrate, a plurality of fingers in ohmic contact with the substrate, and a plurality of pads on the substrate. The plurality of pads effectively form a plurality of discontinuous busbars. Two of the fingers extend from a first pad of the plurality of pads. Specifically, a given one of the two fingers (“given finger”) may connect with a second pad of the plurality of pads. This given finger may have an inter-pad portion between the first and second pads. The cell further has a tab at least partially covering the inter-pad portion of the given finger.Type: ApplicationFiled: July 29, 2009Publication date: January 7, 2010Applicant: EVERGREEN SOLAR, INC.Inventors: Kevin J. Gray, Chistopher E. Dubé, Michael A. Ralli, Thomas S. LaMotte, Stephen Fox
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Publication number: 20090301386Abstract: A method of growing a ribbon crystal provides a crucible containing molten material and passes string through the molten material to grow the ribbon crystal. The method further directs gas flow around the ribbon crystal such that the gas flows down along the ribbon crystal toward the crucible.Type: ApplicationFiled: August 17, 2009Publication date: December 10, 2009Applicant: EVERGREEN SOLAR, INC.Inventors: David Harvey, Weidong Huang, Scott Reitsma, Minh Sy Le
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Publication number: 20090159114Abstract: A photovoltaic cell has a photosensitive substrate and a plurality of fingers in ohmic contact with the substrate. At least one of the fingers has an average width of less than about 95 microns. The cell also has a plurality of busbars in ohmic contact with the fingers. At least two of the busbars that are spaced less than about 38 millimeters apart intersect the at least one finger (i.e., the finger(s) having an average width of less than about 95 microns).Type: ApplicationFiled: December 10, 2008Publication date: June 25, 2009Applicant: EVERGREEN SOLAR, INC.Inventors: Brown Williams, Christopher E. Dube, Stephen Fox, Andrew Gabor, Michael A. Ralli
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Publication number: 20090145479Abstract: A shaped tab conductor configured to allow more incident light to strike a cell substrate, improving the photovoltaic efficiency of the cell. The shaped tab conductor is configured to reduce the amount of incident light that is blocked by the tab from reaching the surface of the cell substrate. The tab may also be configured to redirect light reflected from the cell surface back to the cell surface. The cross-section of the tab conductor may be polygonal, such as a rhombus, with at least one generally planar surface that forms an acute angle with the substrate.Type: ApplicationFiled: December 10, 2008Publication date: June 11, 2009Applicant: Evergreen Solar, Inc.Inventor: Brown Williams