Monolithic series-connected solar cells employing shorted p-n junctions for electrical isolation

• US 4,933,021 A
• Filed: 11/14/1988
• Issued: 06/12/1990
• Est. Priority Date: 11/14/1988
• Status: Expired due to Fees

• Current Assignee: Electric Power Research Institute, Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Electric Power Research Institute
• Inventors: Swanson, Richard M.
• Primary Examiner(s): Weisstuch, Aaron
• Application Number:
  US07/272,129
• Time in Patent Office: 575 Days
• Field of Search: 136/249 MS
• US Class Current: 136/249
• CPC Class Codes: H01L 31/03529 Shape of the potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/0475 PV cell arrays made by cells in a planar, e.g. repetitive, configuration on a single semiconductor substrate; PV cell microarrays PV modules composed of a plurality of thin film solar cells deposited on the same substrate H01L31/046
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

Electrical isolation between cells in a dual metal layer contact solar cell or an interdigitated contact solar cell structure is provided by forming a plurality of p-n junctions in the semiconductor substrate of the structure between cells and shorting the p-n junctions by the metallization serially interconnecting adjacent cells. The shorted p-n junctions function as minority carrier traps for minority carriers flowing between the cells.

Claims

1. A solar cell structure comprising

a semiconductor substrate,

a plurality of cells formed in one surface of said substrate, each cell formed in one surface of said substrate, each cell having alternate rows of p-type and n-type regions formed in said one surface, a first metal contact structure contacting all p-type regions and a second metal contact structure contacting all n-type regions, said first and second metal contact structures serially connecting a cell with adjacent cells, and p1 an array of shorted p-n junctions between adjacent cells in contact with said first and second metal contact structures serially connecting adjacent cells and shorted thereby, whereby said shorted p-n junctions function as minority carrier traps between adjacent cells.

2. The solar cell structure as defined by claim 1 wherein said first and second metal contact structures each contact opposite conductivity type regions in adjacent cells.

3. The solar cell structure as defined by claim 1 wherein said semiconductor substrate comprises silicon.

4. In a solar cell structure having a plurality of contacts with at least a first contact contacting doped regions of a first conductivity type and at least a second contact contacting doped regions of opposite conductivity type, said first and second contacts serially connecting said solar cell with adjacent cells formed in a common semiconductor substrate, means for increasing electrical isolation between adjacent cells comprising

a first plurality of doped regions of one conductivity type and a second plurality of doped regions of opposite conductivity type, said first and second pluralities of doped regions cooperatively forming p-n junctions between adjacent cells, and

means for shorting said p-n junctions whereby said p-n junctions function as minority carrier traps.

5. The means for increasing electrical isolation as defined by claim 4 wherein said means for shorting said p-n junctions comprises one of said contacts in said solar cell structure.

6. The means as defined by claim 5 wherein said first and second contacts are interdigitated contacts.