Producing thin film photovoltaic modules with high integrity interconnects and dual layer contacts

• US 6,288,325 B1
• Filed: 05/04/2000
• Issued: 09/11/2001
• Est. Priority Date: 07/14/1998
• Status: Expired due to Fees

• Current Assignee: BP Solar International Incorporated (BP PLC)
• Original Assignee: BP Corporation North America Incorporated (BP PLC)
• Inventors: Jansen, Kai W., Maley, Nagi
• Primary Examiner(s): DIAMOND, ALAN D
• Application Number:
  US09/564,209
• Time in Patent Office: 495 Days
• Field of Search: 136/249 MS, 136/249 TJ, 136/258 PC, 136/258 AM, 136/251, 136/255, 136/256, 136/259, 257/53, 257/55, 257/51, 257/433, 257/443, 257/457, 257/461
• US Class Current: 136/249
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10788 containing ethylene vinylacetate
• CPC Class Codes: H01L 31/03921 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/046 PV modules composed of a plurality of thin film solar cells deposited on the same substrate
• CPC Class Codes: H01L 31/0463 characterised by special patterning methods to connect the PV cells in a module, e.g. laser cutting of the conductive or active layers
• CPC Class Codes: H01L 31/075 the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
• CPC Class Codes: H01L 31/076 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/1824 Special manufacturing methods for microcrystalline Si, uc-Si
• CPC Class Codes: H01L 31/202 including only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/541 CuInSe2 material PV cells
• CPC Class Codes: Y02E 10/545 Microcrystalline silicon PV cells
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

High performance photovoltaic modules are produced with improved interconnects by a special process. Advantageously, the photovoltaic modules have a dual layer back (rear) contact and a front contact with at least one layer. The front contact and the inner layer of the back contact can comprise a transparent conductive oxide. The outer layer of the back contact can comprise a metal or metal oxide. The front contact can also have a dielectric layer. In one form, the dual layer back contact comprises a zinc oxide inner layer and an aluminum outer layer and the front contact comprises a tin oxide inner layer and a silicon dioxide dielectric outer layer. One or more amorphous silicon-containing thin film semiconductors can be deposited between the front and back contacts. The contacts can be positioned between a substrate and an optional superstrate. During production, the transparent conductive oxide layer of the front contact is scribed by a laser, then the amorphous silicon-containing semiconductors and inner layer of the dual layer back contact are simultaneously scribed and trenched (drilled) by the laser and the trench is subsequently filled with the same metal as the outer layer of the dual layer back contact to provide a superb mechanical and electrical interconnect between the front contact and the outer layer of the dual layer back contact. The outer layer of the dual layer back contact can then be scribed by the laser. For enhanced environmental protection, the photovoltaic modules can be encapsulated.

Claims

1. A photovoltaic module, comprising:

a front contact;

a back contact;

each of said contacts comprising a semiconductor comprising a transparent conductive oxide selected from the group consisting of tin oxide, indium-tin oxide, zinc oxide, and cadmium stannate;

at least one amorphous silicon-containing cell positioned between said contacts;

a substrate positioned adjacent one of said contacts opposite said cell such that said adjacent contact is positioned between said cell and said substrate;

the back contact comprising a dual layer comprising said transparent conductive oxide and a metallic layer comprising a metal selected from the group consisting of aluminum, silver, molybdenum, platinum, steel, iron, niobium, titanium, chromium, bismuth, antimony, and the oxides of the preceding and;

at least one interconnect extending between the metallic layer of the back contact and the front contact and connecting the metallic layer with the front contact, said interconnect being formed by laser scribing a trench through the transparent conductive oxide layer of the back contact and said amorphous silicon-containing cell and immediately thereafter filling said trench with said metallic layer.

2. A photovoltaic module in accordance with claim 1 wherein said amorphous silicon-containing cell comprises a portion of a solar cell selected from the group consisting of hydrogenated amorphous silicon, hydrogenated amorphous silicon carbon, and hydrogenated amorphous silicon germanium.

3. A photovoltaic module in accordance with claim 1 wherein said cell is selected from the group consisting of a single junction cell, a tandem junction cell, a multi-junction cell, a p-i-n cell, a n-i-p cell, and a cell comprising microcrystalline silicon.

4. A photovoltaic module in accordance with claim 1 wherein said substrate is selected from the group consisting of a vitreous substrate, a glass substrate, a stainless steel substrate, and a metal substrate.

5. A photovoltaic module in accordance with claim 1 wherein said transparent conductive oxide of said dual layer contact comprises zinc oxide.

6. A photovoltaic module in accordance with claim 1 wherein said metal in said metallic layer of said dual layer contact comprises aluminum.

7. A photovoltaic module in accordance with claim 1 wherein said front contact comprises a dielectric layer.

8. A photovoltaic module in accordance with claim 1 wherein:

said interconnect comprises the same metal as said metallic layer of said dual layer back contact.

9. A photovoltaic module, comprising:

a multi-junction solar cell selected from the group consisting of a tandem solar cell, a dual junction solar cell, and a triple junction solar cell, said multi- junction solar cell comprising;

a vitreous light-transmissive substrate selected from the group consisting of transparent glass and translucent glass;

a front contact comprising a transparent metallic oxide layer on said vitreous light-transmissive substrate, said transparent metallic oxide layer comprising a front semiconductor being selected from the group consisting of tin oxide, indium-tin oxide, zinc oxide, and cadmium stannate;

a dual layer back contact comprising an outer metallic layer and an inner layer;

said outer metallic layer of said dual layer back contact comprising a metal selected from the group consisting of aluminum, silver, molybdenum, platinum, steel, iron, niobium, titanium, chromium, bismuth, antimony, and oxides of the preceding;

said inner layer of said dual layer back contact comprising a semiconductor comprising a transparent conductive oxide selected from the group consisting of zinc oxide, tin oxide, indium-tin oxide, and cadmium stannate;

an amorphous silicon cell comprising hydrogenated amorphous silicon positioned adjacent and abutting against said front semiconductor of said front contact;

an amorphous silicon germanium cell comprising hydrogenated amorphous silicon germanium abutting against said amorphous silicon cell and being positioned between said amorphous silicon cell and said semiconductor of said dual layer back contact; and

at least one interconnect extending between the metallic layer of the back contact and the front contact and connecting the metallic layer with the front contact, said interconnect being formed by laser scribing a trench through the transparent conductive oxide layer of the back contact and said amorphous silicon-containing cells and immediately after filling said trench with said metallic layer.

10. A photovoltaic module in accordance with claim 9 including:

a vitreous light-transmissive superstrate selected from the group consisting of transparent glass, and opaque glass; and

an encapsulant comprising ethylene vinyl acetate positioned between and abutting against said superstrate and said outer metallic layer of said dual layer back contact.

11. A photovoltaic module in accordance with claim 9 wherein:

said outer metallic layer of said dual layer back contact comprises aluminum;

said interconnect comprises aluminum; and

said inner layer of said dual layer back contact comprises zinc oxide.

12. A photovoltaic module in accordance with claim 11 wherein:

said transparent metallic oxide layer of said front contact comprises tin oxide; and

said cells are selected from the group consisting of p-i-n cells and n-i-p cells.

13. A photovoltaic module in accordance with claim 12 wherein said front contact further comprises a dielectric layer comprising silicon dioxide positioned on said tin oxide.

14. A photovoltaic module in accordance with claim 9 including a microcrystalline silicon cell positioned between and abutting against said amorphous silicon germanium cell and said semiconductor of said dual layer back contact.

15. A photovoltaic module in accordance with claim 9 wherein said multi-junction cell comprises a microcrystalline segment selected from the group consisting of a microcrystalline tunnel junction, a p-doped microcrystalline layer, and an n-doped microcrystalline layer.

16. A photovoltaic module, comprising:

a multi-junction solar cell comprising;

a vitreous light-transmissive substrate selected from the group consisting of transparent glass and translucent glass;

a front contact comprising a transparent metallic oxide layer on said vitreous light-transmissive substrate, said transparent metallic oxide layer comprising a front semiconductor selected from the group consisting of tin oxide, indium-tin oxide, zinc oxide, and cadmium stannate;

a dual layer back contact comprising an outer metallic layer and an inner layer;

said outer metallic layer of said dual layer back contact comprising a metal selected from the group consisting of aluminum, silver, molybdenum, platinum, steel, iron, niobium, titanium, chromium, bismuth, antimony, and oxides of the preceding;

said inner layer of said dual layer back contact comprising a semiconductor comprising a transparent conductive oxide selected from the group consisting of zinc oxide, tin oxide, indium-tin oxide, and cadmium stannate;

an amorphous silicon cell comprising hydrogenated amorphous silicon;

an amorphous silicon germanium cell comprising hydrogenated amorphous silicon germanium;

a microcrystalline segment selected from the group consisting of a microcrystalline tunnel junction, a p-doped microcrystalline layer, and an n-doped microcrystalline layer; and

at least one interconnect extending between the metallic layer of the back contact and the front contact and connecting the metallic layer with the front contact, said interconnect being formed by laser scribing a trench through the layers comprising the amorphous silicon cell, the amorphous silicon germanium cell and the microcrystalline segment.