成果報告書詳細
管理番号20090000000288
タイトル*平成20年度中間年報 新エネルギー技術開発 太陽光発電システム未来技術研究開発 新構造超薄型多結晶シリコン太陽電池の研究開発
公開日2009/8/21
報告書年度2008 - 2008
委託先名京セラ株式会社
プロジェクト番号P07015
部署名新エネルギー技術開発部 太陽電池グループ
和文要約以下本編抜粋:1. 研究開発の内容及び成果等 [平成20年度目標(中間目標)] 厚さ100μm、面積15cm 角相当の多結晶シリコン太陽電池セルで変換効率18%を達成する。
英文要約Title : R&D for Next Generation PV Systems, Research and Development on Ultra-thin Multi-Crystalline Silicon Solar Cells with New Structure (FY2006-2009) FY2008 Annual Report [Objective of FY2008]18.0% Cell Efficiency on Multi-Crystalline Solar Cell at 100μm thickness and 15cm x 15cm wafer size.[Accomplishment]We have continued to develop the multi-crystalline back-contact cell. This is the so-called Metal wrap Through (MWT) back-contact cell which has the n-contact busbar on the rear side of the cell thus significantly reduces the front side contact area. The excellent part of the MWT is that it can be produced in our readily available production line if we only add the via drilling laser equipment.Last year, we had achieved 17.1% cell efficiency at 100μm thickness. The problem with this cell was the lower cell efficiency and the worse cell bow. The lower cell efficiency was due to the spectral response drop in the long wavelength on 100μm cells than 180μm ones. The light absorption at Al-BSF layer is more significant on thinner cells therefore it needs to be replaced with passivation layers to reduce the light absorption but maintain the suppression of carrier recombination. The cell bow was due to the same amount of Al-BSF layer on thinner cell module process is challenging with larger cell bow because of the cell crack and increase of the cell stress during the tabbing process. Therefore the stress needs to be relieved. We have produced the single-cell-module without cell breakage by applying our stress relieving technique. The power drop rate from cell to module was maintained at the same level as our conventional cells. The cell strength was tested on cells with tabs and the strength was found to be at the same level as the conventional cells which means that the cell did not crack during the tabbing process. Considering this result, we have made the commercial size module with the same back contact cells. The module was free from cell cracks with better appearance by the elimination of front side busbar.A new approach is needed to reduce the cell bow and raise the cell efficiency. This approach includes the development of new type of rear-side-grid as a replace of conventional Aluminum grid and of the new texture to improve the rear-side reflection and enhance the light trapping property. As the cell becomes thinner, the cell bow becomes worse at the traditional aluminum printing and firing process. The worse cell bow leads to lower production yield therefore an alternative process is necessary. By replacing the Aluminum with the passivation film, it suppresses the cell bow and improves the rear side reflection property thus raise the cell efficiency. Currently, we are developing process of the grid and passivation film deposition to improve the spectral response in the long wavelength. Our best cell achieved 17.1% with respect to our initial goal of 18.0%. The dendrite evaluation, the new project this year, is also underway. We have obtained the 10cm x 10cm wafer with dendrite from Tohoku University and is being evaluated.
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