Flexible cells and modules produced using roll-to-roll electroplating approach

Abstract

Thin film Cu(In,Ga)Se2 (CIGS) photovoltaic cells are considered to have a high potential for low cost electricity production due to their demonstrated high conversion efficiencies. Various methods have been used to make thin film CIGS solar cells. In the present approach, a low cost roll-to-roll electroplating process is utilized to deposit the CIGS precursor layers. The electroplating technology provides well controlled composition along the length and width of the flexible substrates demonstrating its suitability as a low cost CIGS precursor deposition method. Precursor layers are then subjected to rapid thermal processing to form a photovoltaic-grade CIGS absorber. The processing is done using roll-to-roll production equipment on a flexible metallic substrate. The CIGS based solar cells are fully finished in roll form and then cut into large area cells. The cells are then interconnected to fabricate panels with about 1.1 m 2 aperture area and about 115W power output. These rigid panels show excellent stability under damp heat test conditions and are certified against both UL and IEC standards. More recent work has focused on lightweight flexible solar modules. These modules open new application areas and can further lower the cost of systems by lowering the installation costs. Flexible modules with aperture area efficiency as high as 11.2 % have been demonstrated. Standard module certification tests, including 1000 hour damp heat test, show very small changes of Pmax .

Review of progress toward 20% efficiency flexible CIGS solar cells and manufacturing issues of solar modules

“…SoloPower is using such an ap proach for cells grown on stainless steel substrates [59]. A third interconnection method, the so-called shingling, can be used for conductive substrates or in combination with conductive tape for insulating substrates.…”

“…Such materials could meet the WVTR requirements, but up to now they are more expensive than EVAs. Several flex ible CIGS modules have obtained UL or IEC certifications (for example, SoloPower [59], [71] and Global Solar [72]). These certifications are not based on real lifetime predictions as done by Coyle et al [67], [73], but they certify that a given CIGS module can withstand a 2000-h damp heat test.…”

Laser processing for thin film chalcogenide photovoltaics: a review and prospectus

“…These applications have recently been reviewed in the literature. 7,8 In thin film photovoltaics (PV), lasers have been used for the recrystallization of amorphous Si into polycrystalline Si 9,10 and scribing for the monolithic cell integration of CdTe 11 and CuðIn; GaÞðS; SeÞ 2 (CIGS) 11,12 cells. The aim of this paper is to review laser-based processes for synthesizing and or improving the properties of the chalcogenide absorber layers used in thin film solar cells, namely CdTe and Cu(In, Ga)S(Se).…”

Electrodeposition of Novel Precursor Structures for Efficient Copper Indium Gallium Selenide (CIGS) Films

“…We also obtained efficiencies up to 13% on 120 cm 2 cells and aperture efficiencies up to 12.1% for our lightweight flexible modules from our roll-to-roll manufacturing line. More detailed results from our roll-to-roll electroplating approach for the fabrication of flexible cells were given in some recent publications (5,6). Figure 1.J-V characteristics of an 11.8 cm2 area CIGS solar cell with an efficiency of 14.17%.…”