Integrated thin film solar cell interconnection

Abstract

Photovoltaic modules may include multiple flexible thin film photovoltaic cells electrically connected in series, and laminated to a substantially transparent top sheet having a conductive grid pattern facing the cells. Methods of manufacturing photovoltaic modules including integrated multi-cell interconnections are provided. Methods may include steps of coordinating, integrating, and registering multiple rolls of substrates in continuous processes.

1 . A method of manufacturing a photovoltaic module comprising:
 manufacturing a continuous roll of photovoltaic material having a front side, a back side, a length and a width, the photovoltaic material including a conductive substrate, and a photoactive composition applied to the front side of the substrate;   applying an insulating transmissive top sheet to the substrate, the top sheet having a conductive grid pattern contacting the photoactive composition;   singulating pieces of the roll into a series of discrete photoactive cells after applying the top sheet to the photovoltaic material, each cell having a negative side and a positive side; and   electrically interconnecting the negative side of one cell to the positive side of an adjacent cell.   
     
     
         2 . The method of  claim 1 , wherein the photoactive composition comprises CIGS. 
     
     
         3 . The method of  claim 1 , wherein the interconnecting step includes the step of creating one or more vias through each cell, and placing ECA in each via. 
     
     
         4 . The method of  claim 1 , further comprising the step of:
 scribing discreet cell regions in the photovoltaic material by cutting through the photoactive composition without cutting through the conductive substrate.   
     
     
         5 . The method of  claim 1 , further comprising:
 laminating a back sheet to the back side of the photovoltaic material.   
     
     
         6 . The method of  claim 5 , wherein the back sheet includes an insulating sheet and a conductive grid pattern configured to carry current from the negative side of one cell to the positive side of an adjacent cell. 
     
     
         7 . The method of  claim 6 , wherein the interconnecting step includes the step of creating one or more vias through each cell, placing ECA in each via, and connecting the grid of the top sheet to the grid pattern on the back sheet through the vias. 
     
     
         8 . The method of  claim 1 , further comprising:
 providing a conductive return line in parallel with the series of discrete photoactive cells.   
     
     
         9 . The method of  claim 1 , further comprising:
 providing an exposed area of each cell extending beyond the grid pattern of the top sheet for testing the cell during the manufacturing process.   
     
     
         10 . The method of  claim 8 , further comprising:
 providing positive and negative contacts near a same side of the module by cutting a selected segment of the photovoltaic material, and electrically connecting a cell at one end of the segment, to the return line.   
     
     
         11 . The method of  claim 4 , further comprising:
 scribing pad areas along a perimeter of each cell region by cutting through the photoactive composition without cutting through the conductive substrate.   
     
     
         12 . The method of  claim 11 , further comprising:
 providing tab portions on the grid pattern of the top sheet.   
     
     
         13 . The method of  claim 12 , further comprising:
 registering and electrically connecting tab portions on the grid pattern of the top sheet with pad areas on the substrate of the photovoltaic material.   
     
     
         14 . The method of  claim 1 , wherein the singulating step includes the step of:
 defining long edges of each cell by cutting a series of parallel lines extending most of the way across the width of the photovoltaic material prior to the applying step, and trimming edge portions of the photovoltaic material after the applying step.   
     
     
         15 . The method of  claim 1 , further comprising:
 providing an attachment mechanism configured to fix the photovoltaic module to an exterior surface of a building.   
     
     
         16 . The method of  claim 15 , wherein the attachment mechanism includes a protective back sheet laminated on the back side of the photovoltaic material, the protective back sheet having an exterior side, and adhesive applied to the exterior side of the back sheet. 
     
     
         17 . The method of  claim 15 , wherein the attachment mechanism includes an attachment region of the module extending beyond the photoactive cells. 
     
     
         18 . The method of  claim 15 , further comprising fixing the module to an exterior surface of a building by nailing or stapling the attachment region to the exterior surface. 
     
     
         19 . A process for producing a thin-film photovoltaic device comprising:
 manufacturing a continuous roll of photovoltaic material having a length and a width, including a conductive substrate, and a photoactive composition applied to a front side of the substrate, the material having a positive side and a negative side;   singulating pieces of the roll into a photovoltaic series including a first cell and a second cell, each cell having a positive side and a negative side;   creating at least a partial aperture in each cell; and   electrically connecting the negative side of the first cell to the positive side of the second cell through the at least partial aperture in the first cell.   
     
     
         20 . The process of  claim 19 , wherein the at least partial aperture is a complete aperture located in an inner region of the cell. 
     
     
         21 . The process of  claim 20 , further comprising:
 applying a diectric material around the at least partial apertures.   
     
     
         22 . The process of  claim 19 , wherein the singulating step includes:
 partially singulating cells from the roll by making repeating parallel cuts through the roll, substantially perpendicular to the length of the roll; and   subsequently trimming the roll on opposite sides parallel to the length of the roll to complete singulation of discrete cells.   
     
     
         23 . The process of  claim 19 , further comprising:
 applying a metal pattern to the positive side of the roll, wherein the metal pattern has a continuous portion situated under at least part of the first cell and at least part of the second cell.   
     
     
         24 . The process of  claim 19 , wherein the at least partial aperture is defined as a via, and further comprising:
 applying an electrically conductive adhesive in the via to establish an electrical connection between a negative side one cell to the positive side of an adjacent cell.   
     
     
         25 . The process of  claim 19  further comprising:
 applying a bus grid pattern to the negative side of each cell, the bus pattern intersecting with the at least partial aperture of each cell. 
 
     
     
         26 . The process of  claim 23 , wherein the metal pattern has a spring component under each cell. 
     
     
         27 . The process of  claim 19 , wherein the photovoltaic series has a positive end and a negative end, further comprising:
 providing a conductive return line from one end of the series to near the other end of the series.   
     
     
         28 . The process of  claim 19 , wherein each at least partial aperture is defined as a via, further comprising:
 scribing a circuit around each via; and   depositing a dielectric material around each via and corresponding scribed circuit.   
     
     
         29 . An intermediate article of manufacture comprising:
 a flexible web substrate in roll form, the web substrate having first and second edge portions and a width dimension defined between the edge portions, the web substrate having a front side, a back side, and a photoactive layer deposited on the front side of the web substrate, wherein the web substrate has a series of linear cuts running across the width dimension of the web defining partially singulated photovoltaic cells regions, the linear cuts running most of the way between the first and second edge portions of the web substrate, without completely cutting the web substrate, while maintaining enough connection between cell regions to provide sufficient tensile strength for the web substrate to roll up, roll out, and translate through a processing area.   
     
     
         30 . The intermediate article of manufacture of  claim 29 , further comprising:
 a transparent top sheet applied to the front side of the web substrate covering the photoactive layer, the top sheet having a conductive grid pattern in contact with the photoactive layer of the web substrate.   
     
     
         31 . The intermediate article of manufacture of  claim 29 , wherein the web substrate is conductive. 
     
     
         32 . The intermediate article of manufacture of  claim 30 , wherein the top sheet is made of an insulating material. 
     
     
         33 . The intermediate article of manufacture of  claim 29 , wherein the each cell region has a via for conducting current from the front side of the web substrate. 
     
     
         34 . The intermediate article of manufacture of  claim 29 , wherein each edge portion of each cell region has a via for creating a bypass diode. 
     
     
         35 . A photovoltaic assembly comprising:
 a flexible web substrate material having a long axis and a short axis corresponding to a width of the web;   a string of thin film flexible photovoltaic cells connected in series along the long axis of the web substrate;   a conductive return line running parallel to the string, the return line being separate from the cells; and   a conductive segment configured for attachment from the return line to a selected cell along the string.   
     
     
         36 . The photovoltaic assembly of  claim 35 , wherein the web substrate is conductive. 
     
     
         37 . The photovoltaic assembly of  claim 35 , wherein web substrate includes a dielectric back sheet having a metal pattern for conducting current between adjacent cells, the return line being patterned on the back sheet. 
     
     
         38 . The photovoltaic assembly of  claim 35  further comprising a Transmissive dielectric top sheet having a conductive grid pattern contacting the photovoltaic cells. 
     
     
         39 . A method of manufacturing a photovoltaic module comprising:
 manufacturing a continuous roll of photovoltaic material including a conductive substrate, and a photoactive composition applied to a front side of the substrate, the material having a positive side and a negative side, the substrate having a length, a width, and a pair of edge portions;   cutting through the conductive substrate and photoactive composition to form a series of linear apertures extending most of the way across the width without completely severing the substrate, each pair of adjacent apertures defining a partially singulated photovoltaic cell;   laminating a top sheet to the substrate;   trimming the edge portions of the substrate to complete singulation of individual cells without severing the top sheet; and   electrically interconnecting adjacent cells in series.   
     
     
         40 . The method of  claim 39 , further comprising:
 laminating a back sheet having first conductive grid on a back side of the photovoltaic material.   
     
     
         41 . The method of  claim 40 , wherein the top sheet has a second grid, further comprising:
 electrically interconnecting adjacent cells by partially overlapping the first and second grids.   
     
     
         42 . The method of  claim 41 , wherein grid overlapping occurs near an outer edge of a cell. 
     
     
         43 . The method of  claim 41 , wherein grid overlapping occurs between two cells. 
     
     
         44 . The method of  claim 41 , wherein grid overlapping occurs on opposite side of a via in a cell. 
     
     
         45 . The method of  claim 41 , wherein ECA connects the grids in an overlapping region. 
     
     
         46 . A thin film photovoltaic module comprising:
 a flexible photovoltaic substrate in roll form including a conductive sheet having a front side and a back side, and a photovoltaic layer applied to the front side of the conductive sheet, wherein the photovoltaic layer has a scribe pattern defining a series of discrete cell regions on top of the continuous conductive sheet; and   a transmissive top sheet attached to the top side of the conductive sheet, the top sheet having a conductive grid contacting the photovoltaic layer, wherein the conductive grid has a series of discrete circuits, each circuit being registered with respect to one of the cell regions and having at least one tab portion which is electrically connected to the conductive sheet in a pad area corresponding to an adjacent cell region.   
     
     
         47 . The thin film photovoltaic module of  claim 46 , further comprising:
 a protective sheet laminated on the back side of the photovoltaic substrate.   
     
     
         48 . A method of testing individual cells in a process of manufacturing a photovoltaic module comprising:
 manufacturing a continuous roll of photovoltaic material having a length and a width, including a conductive substrate, and a photoactive composition applied to a front side of the substrate, the material having a positive side and a negative side;   singulating pieces of the roll into a series of discrete photoactive cells applied to an insulating transmissive top sheet, wherein the top sheet has a conductive grid pattern contacting the photoactive composition, each of the cells having an exposed area extending beyond the top sheet; and   testing individual cells by contacting a test electrode to the exposed area of a given cell during the manufacturing process.   
     
     
         49 . The method of  claim 48 , further comprising:
 applying a dielectric cover over the exposed areas of the cells after the testing step.   
     
     
         50 . The method of  claim 48 , further comprising:
 applying a back sheet to the substrate, the back sheet being made of an insulating material and having a conductive grid for conducting current from one cell to an adjacent cell.   
     
     
         51 . A photovoltaic module comprising:
 a flexible conductive web substrate in roll form, the web substrate having first and second edge portions and a width dimension defined between the edge portions, the web substrate having a front side, a back side, and a photoactive layer deposited on the front side of the web substrate, wherein the photoactive layer is scribed into a pattern of discrete cell regions, each cell region having one more contact pads providing exposed substrate areas; and   a conductive grid connecting the top side of a cell region to the one or more contact pads of an adjacent cell region.   
     
     
         52 . The photovoltaic module of  claim 51 , wherein the conductive grid is patterned on an insulating transmissive top sheet.