Innovative Approaches to Low Cost Module Manufacturing of String Ribbon Si PV Modules: Phase II, Annual Technical Progress Report, 1 April 2003--31 May 2004

George Mooney, David Mooney (NREL Technical Monitor)

Research output: NRELSubcontract Report

Abstract

This subcontract resulted in a number of important advances for Evergreen Solar Inc. Foremost amongst these is the production implementation of dual ribbon growth from a single crucible (Gemini) using the String Ribbon continuous ribbon technology. This project has resulted in the flattest ribbon and the highest yields and machine uptime ever seen at Evergreen Solar. This then has resulted insignificantly lowered consumables costs and lower overall direct manufacturing costs. In addition, methods to control the as-grown surface of Gemini ribbon have permitted the usage of the so-called no-etch process that allows for direct transfer of as-grown ribbon to diffusion without any intermediate etching step. In-line diagnostics for Gemini were further developed -- these included moreaccurate methods for measuring and controlling melt depth and more accurate means to measure and control ribbon thickness. Earlier in the project, the focus was on monolithic module development. With the Gemini advances described above, monolithic module work was brought to a close during this second year of the overall three year project. A significant advance in this technology was thedevelopment of a conductive adhesive in combination with Evergreen's proprietary backskin and encapsulant. 25-W size experimental monolithic modules have been tested and found to be able to withstand up to 1400 thermal cycles.
Original languageAmerican English
Number of pages26
StatePublished - 2004

Bibliographical note

Work performed by Evergreen Solar, Inc., Marlboro, Massachusetts

NREL Publication Number

  • NREL/SR-520-36908

Keywords

  • backskin
  • coefficient of thermal expansion (CTE)
  • conductive adhesive
  • encapsulant
  • gemini-dual ribbon growth
  • in-situ diagnostics
  • manufacturer
  • monolithic
  • no-etch process
  • oxide thickness
  • PV module
  • string ribbon
  • thermal cycles

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