Low-cost high-efficiency solar module using epitaxial si thin-film absorber and double-sided heterojunction solar cell with integrated module fabrication

Abstract

One embodiment of the present invention provides a double-sided heterojunction solar cell module. The solar cell includes a frontside glass cover, a backside glass cover situated below the frontside glass cover, and a number of solar cells situated between the frontside glass cover and the backside glass cover. Each solar cell includes a semiconductor multilayer structure situated below the frontside glass cover, including: a frontside electrode grid, a first layer of heavily doped amorphous Si (a-Si) situated below the frontside electrode, a layer of lightly doped crystalline-Si (c-Si) situated below the first layer of heavily doped a-Si, and a layer of heavily doped c-Si situated below the lightly doped c-Si layer. The solar cell also includes a second layer of heavily doped a-Si situated below the multilayer structure; and a backside electrode situated below the second layer of heavily doped a-Si.

What is claimed is: 
     
         1 . A solar module, comprising:
 a first photovoltaic structure;   a second photovoltaic structure positioned adjacent to the first photovoltaic structure, wherein each of the first and second photovoltaic structures comprises a first electrode positioned on a first surface and a second electrode positioned on an opposite surface; and   wherein a solder tab of the first electrode of the first photovoltaic structure is in direct contact with a solder tab of the second electrode of the second photovoltaic structure, thereby enabling a serial connection between the first and second photovoltaic structures.   
     
     
         2 . The solar module of  claim 1 , further comprising:
 a first cover; and   a second cover.   
     
     
         3 . The solar module of  claim 2 , further comprising:
 a first adhesive polymer layer positioned between the first cover and the photovoltaic structures; and   a second adhesive polymer layer positioned between the second cover and the photovoltaic structures;   wherein the first and second adhesive polymer layers, the first and second covers, and the first and second photovoltaic structures are laminated together.   
     
     
         4 . The solar module of  claim 3 , wherein the first cover comprises glass, and wherein a refractive index of the first adhesive polymer layer matches a refractive index of the glass. 
     
     
         5 . The solar module of  claim 4 , wherein the first adhesive polymer layer comprises one or more selected from a group consisting of: ethylene-vinyl acetate (EVA), acrylic, polycarbonate, polyolefin, and thermal plastic. 
     
     
         6 . The solar module of  claim 1 , wherein each of the first and second photovoltaic structures comprises:
 a lightly doped crystalline-Si layer positioned between the first and second electrodes;   a first heavily doped amorphous Si layer positioned between the first electrode and the lightly doped crystalline-Si layer; and   a second heavily doped amorphous Si layer positioned between the second electrode and the lightly doped crystalline-Si layer, wherein the first and second heavily doped amorphous Si layers have opposite conductive doping types.   
     
     
         7 . The solar module of  claim 6 , wherein each of the first and second photovoltaic structures further comprises at least one transparent conductive oxide layer positioned between an electrode and a heavily doped amorphous Si layer. 
     
     
         8 . The solar module of  claim 6 , wherein the lightly doped crystalline-Si layer is formed using a chemical vapor deposition technique, wherein a thickness of the lightly doped crystalline-Si layer is between 5 μm and 100 μm, and wherein a doping concentration for the lightly doped c-Si layer is between 1×10 16 /cm 3  and 1×10 17 /cm 3 . 
     
     
         9 . The solar module of  claim 6 , wherein at least one heavily doped crystalline-Si layer is formed using a chemical vapor deposition technique, wherein a thickness of the at least one heavily doped crystalline-Si layer is between 10 nm and 50 nm, and wherein a doping concentration of the at least one heavily doped a-Si layer is between 1×10 17 /cm 3  and 1×10 20 /cm 3 . 
     
     
         10 . The solar module of  claim 6 , wherein each of the first and second photovoltaic structures further comprises a passivation layer on at least one surface of the lightly doped crystalline-Si layer, wherein a thickness of the passivation layer is between 1 nm and 10 nm, and wherein the passivation layer includes at least one of: undoped a-Si and SiO x . 
     
     
         11 . The solar module of  claim 1 , wherein the first or second electrode comprises: Cu or tin-lead-silver coated Cu. 
     
     
         12 . A solar panel, comprising:
 a first cover;   a second cover; and   a plurality of photovoltaic structures positioned between the first and second covers, wherein a respective photovoltaic structure comprises a first electrode positioned on a first surface and a second electrode positioned on an opposite surface of the photovoltaic structure; and   wherein the plurality of photovoltaic structures are arranged in a way that a solder tab of the first electrode of a first photovoltaic structure is in direct contact with a solder tab of the second electrode of an adjacent photovoltaic structure, thereby enabling a serial connection between the first photovoltaic structure and the adjacent photovoltaic structure.   
     
     
         13 . The solar panel of  claim 12 , further comprising:
 a first adhesive polymer layer positioned between the first cover and the plurality of photovoltaic structures; and   a second adhesive polymer layer positioned between the second cover and the plurality of photovoltaic structures;   wherein the first and second adhesive polymer layers, the first and second covers, and the plurality of photovoltaic structures are laminated together.   
     
     
         14 . The solar panel of  claim 13 , wherein the first or second adhesive polymer layer comprises one or more selected from a group consisting of: ethylene-vinyl acetate (EVA), acrylic, polycarbonate, polyolefin, and thermal plastic. 
     
     
         15 . The solar panel of  claim 13 , wherein the photovoltaic structure comprises:
 a lightly doped crystalline-Si layer positioned between the first and second electrodes;   a first heavily doped amorphous Si layer positioned between the first electrode and the lightly doped crystalline-Si layer; and   a second heavily doped amorphous Si layer positioned between the second electrode and the lightly doped crystalline-Si layer, wherein the first and second heavily doped amorphous Si layers have opposite conductive doping types.   
     
     
         16 . The solar panel of  claim 15 , wherein the photovoltaic structure further comprises at least one transparent conductive oxide layer positioned between an electrode and a heavily doped amorphous Si layer. 
     
     
         17 . The solar panel of  claim 15 , wherein the lightly doped crystalline-Si layer is formed using a chemical vapor deposition technique, wherein a thickness of the lightly doped crystalline-Si layer is between 5 μm and 100 μm, and wherein a doping concentration for the lightly doped c-Si layer is between 1×10 16 /cm 3  and 1×10 17 /cm 3 . 
     
     
         18 . The solar panel of  claim 15 , wherein at least one heavily doped crystalline-Si layer is formed using a chemical vapor deposition technique, wherein a thickness of the at least one heavily doped crystalline-Si layer is between 10 nm and 50 nm, and wherein a doping concentration of the at least one heavily doped a-Si layer is between 1×10 17 /cm 3  and 1×10 20 /cm 3 . 
     
     
         19 . The solar panel of  claim 15 , wherein the photovoltaic structure further comprises a passivation layer on at least one surface of the lightly doped crystalline-Si layer, wherein a thickness of the passivation layer is between 1 nm and 10 nm, and wherein the passivation layer includes at least one of: undoped a-Si and SiO x . 
     
     
         20 . The solar panel of  claim 12 , wherein the first or second electrode comprises: Cu or tin-lead-silver coated Cu.