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Title: Review of Back Contact Silicon Solar Cells for Low Cost Application


No abstract prepared.

Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM, and Livermore, CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
Report Number(s):
TRN: AH200038%%523
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: 16th European Photovoltaic Solar Energy Conference, Glasgow (GB), 05/01/2000--05/05/2000; Other Information: PBD: 27 Oct 2000
Country of Publication:
United States

Citation Formats

SMITH,DAVID D., and GEE,JAMES M. Review of Back Contact Silicon Solar Cells for Low Cost Application. United States: N. p., 2000. Web.
SMITH,DAVID D., & GEE,JAMES M. Review of Back Contact Silicon Solar Cells for Low Cost Application. United States.
SMITH,DAVID D., and GEE,JAMES M. 2000. "Review of Back Contact Silicon Solar Cells for Low Cost Application". United States. doi:.
title = {Review of Back Contact Silicon Solar Cells for Low Cost Application},
author = {SMITH,DAVID D. and GEE,JAMES M.},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2000,
month =

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  • Back contact solar cells hold significant promise for increased performance in photovoltaics for the near future. Two major advantages which these cells possess are a lack of grid shading loss and coplanar interconnection. Front contacted cells can have up to 10% shading loss when using screen printed metal grids. A front contact cell must also use solder connections which run from the front of one cell to the back of the next for series interconnection. This procedure is more difficult to automate than the case of co-planar contacts. The back contact cell design is not a recent concept. The earliestmore » silicon solar cell developed by Bell Labs was a back contact device. There have been many design modifications to the basic concept over the years. To name a few, there is the Interdigitated Back Contact (IBC) cell, the Stanford Point contact solar cell, the Emitter Wrap Through (EWT), and its many variations. A number of these design concepts have demonstrated high efficiency. The SunPower back contact solar cell holds the efficiency record for silicon concentrator cells. The challenge is to produce a high efficiency cell at low cost using high throughput techniques. This has yet to be achieved with a back contact cell design. The focus of this paper will be to review the relevant features of back contact cells and progress made toward the goal of a low cost version of this device.« less
  • This paper summarizes recent progress in the development of back-contact crystalline-silicon (c-Si) solar cells and modules at Sandia National Laboratories. Back-contact cells have potentially improved efficiencies through the elimination of grid obscuration and allow for significant simplifications in the module assembly process. Optimization of the process sequence has improved the efficiency of our back-contact cell (emitter wrap through) from around 12% to near 17% in the past 12 months. In addition, recent theoretical work has elucidated the device physics of emitter wrap-through cells. Finally, improvements in the assembly processing back-contact cells are described.
  • This paper treats the use of texture etched ZnO:Al films in amorphous silicon solar cells. Chemically textured ZnO:Al films were implemented as a front TCO in p-i-n (superstrate) and n-i-p (substrate) solar cells, and in combination with Ag as a textured back reflector in n-i-p (substrate) solar cells. These cells exhibit excellent optical and light-trapping properties demonstrated by high short-circuit current densities. Adapted microcrystalline p-layers solve the ZnO/p-contact problem and thereby provide high fill factors and open-circuit voltages. The initial efficiencies so far obtained are close to 10% for p-i-n and 8% for n-i-p solar cells.
  • The authors are developing new module concepts that encapsulate and electrically connect all the crystalline-silicon (c-Si) photovoltaic (PV) cells in a module in a single step. The new assembly process (1) uses back-contact c-Si cells, (2) uses a module backplane that has both the electrical circuit, encapsulant, and backsheet in a single piece, and (3) uses a single-step process for assembly of these components into a module. This new process reduces module assembly cost by using planar processes that are easy to automate, by reducing the number of steps, and by eliminating low-throughput (e.g., individual cell tabbing, cell stringing, etc.)more » steps. The authors refer to this process as monolithic module assembly since it translates many of the advantages of monolithic module construction of thin-film PV modules to wafered c-Si PV modules. Preliminary development of the new module assembly process, and some estimations of the cost potential of the new process, are presented.« less
  • Thin hydrogenated amorphous silicon (a-Si:H) layers deposited by hot-wire chemical vapor deposition (HWCVD) are used as both emitters and back contacts in silicon heterojunction solar cells. Low interface recombination velocity and high open-circuit voltage are achieved by a low substrate temperature (<150 deg C) intrinsic a-Si:H deposition which ensures immediate amorphous silicon deposition. This is followed by deposition of doped a-Si:H at a higher temperature (>200 deg C) which appears to improve dopant activation. With an i/n a-Si:H emitter, we obtain a confirmed efficiency of 17.1% on textured p-type float-zone (FZ) silicon with a screen-printed aluminum back-surface-field (Al-BSF) contact. Employingmore » a-Si:H as both the front emitter and the back contact, we achieve a confirmed efficiency of 17.5%, the highest reported efficiency for a p-type c-Si based heterojunction solar cell.« less