INTEGRATED THIN FILM SOLAR CELL INTERCONNECTION
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.
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This application claims priority from U.S. Provisional Patent Application Ser. No. 61/284,956, filed Dec. 28, 2009, Ser. No. 61/284,958 filed Dec. 28, 2009 and Ser. No. 61/284,924 filed Dec. 28, 2009 all of which are incorporated herein by reference. Also incorporated by reference in their entireties are the following patents and patent applications: U.S. Pat. No. 7,194,197, U.S. Pat. No. 6,690,041, Ser. No. 12/364,440 filed Feb. 2, 2009, Ser. No. 12/424,497 filed Apr. 15, 2009 and Ser. No. 12/587,111 filed Sep. 30, 2009.
BACKGROUNDThe field of photovoltaics generally relates to multi-layer materials that convert sunlight directly into DC electrical power. The basic mechanism for this conversion is the photovoltaic effect, first observed by Antoine-César Becquerel in 1839, and first correctly described by Einstein in a seminal 1905 scientific paper for which he was awarded a Nobel Prize for physics. In the United States, photovoltaic (PV) devices are popularly known as solar cells or PV cells. Solar cells are typically configured as a cooperating sandwich of p-type and n-type semiconductors, in which the n-type semiconductor material (on one “side” of the sandwich) exhibits an excess of electrons, and the p-type semiconductor material (on the other “side” of the sandwich) exhibits an excess of holes, each of which signifies the absence of an electron. Near the p-n junction between the two materials, valence electrons from the n-type layer move into neighboring holes in the p-type layer, creating a small electrical imbalance inside the solar cell. This results in an electric field in the vicinity of the metallurgical junction that forms the electronic p-n junction.
When an incident photon excites an electron in the cell into the conduction band, the excited electron becomes unbound from the atoms of the semiconductor, creating a free electron/hole pair. Because, as described above, the p-n junction creates an electric field in the vicinity of the junction, electron/hole pairs created in this manner near the junction tend to separate and move away from junction, with the electron moving toward the electrode on the n-type side, and the hole moving toward the electrode on the p-type side of the junction. This creates an overall charge imbalance in the cell, so that if an external conductive path is provided between the two sides of the cell, electrons will move from the n-type side back to the p-type side along the external path, creating an electric current. In practice, electrons may be collected from at or near the surface of the n-type side by a conducting grid that covers a portion of the surface, while still allowing sufficient access into the cell by incident photons.
Such a photovoltaic structure, when appropriately located electrical contacts are included and the cell (or a series of cells) is incorporated into a closed electrical circuit, forms a working PV device. As a standalone device, a single conventional solar cell is not sufficient to power most applications. As a result, solar cells are commonly arranged into PV modules, or “strings,” by connecting the front of one cell to the back of another, thereby adding the voltages of the individual cells together in electrical series. Typically, a significant number of cells are connected in series to achieve a usable voltage. The resulting DC current then may be fed through an inverter, where it is transformed into AC current at an appropriate frequency, which is chosen to match the frequency of AC current supplied by a conventional power grid. In the United States, this frequency is 60 Hertz (Hz), and most other countries provide AC power at either 50 Hz or 60 Hz.
One particular type of solar cell that has been developed for commercial use is a “thin-film” PV cell. In comparison to other types of PV cells, such as crystalline silicon PV cells, thin-film PV cells require less light-absorbing semiconductor material to create a working cell, and thus can reduce processing costs. Thin-film based PV cells also offer reduced cost by employing previously developed deposition techniques for the electrode layers, where similar materials are widely used in the thin-film industries for protective, decorative, and functional coatings. Common examples of low cost commercial thin-film products include water impermeable coatings on polymer-based food packaging, decorative coatings on architectural glass, low emissivity thermal control coatings on residential and commercial glass, and scratch and anti-reflective coatings on eyewear. Adopting or modifying techniques that have been developed in these other fields has allowed a reduction in development costs for PV cell thin-film deposition techniques.
Furthermore, thin-film cells have exhibited efficiencies approaching 20%, which rivals or exceeds the efficiencies of the most efficient crystalline cells. In particular, the semiconductor material copper indium gallium diselenide (CIGS) is stable, has low toxicity, and is truly a thin film, requiring a thickness of less than two microns in a working PV cell. As a result, to date CIGS appears to have demonstrated the greatest potential for high performance, low cost thin-film PV products, and thus for penetrating bulk power generation markets. Other semiconductor variants for thin-film PV technology include copper indium diselenide, copper indium disulfide, copper indium aluminum diselenide, and cadmium telluride.
Some thin-film PV materials may be deposited either on rigid glass substrates, or on flexible substrates. Glass substrates are relatively inexpensive, generally have a coefficient of thermal expansion that is a relatively close match with the CIGS or other absorber layers, and allow for the use of vacuum deposition systems. However, when comparing technology options applicable during the deposition process, rigid substrates suffer from various shortcomings during processing, such as a need for substantial floor space for processing equipment and material storage, expensive and specialized equipment for heating glass uniformly to elevated temperatures at or near the glass annealing temperature, a high potential for substrate fracture with resultant yield loss, and higher heat capacity with resultant higher electricity cost for heating the glass. Furthermore, rigid substrates require increased shipping costs due to the weight and fragile nature of the glass. As a result, the use of glass substrates for the deposition of thin films may not be the best choice for low-cost, large-volume, high-yield, commercial manufacturing of multi-layer functional thin-film materials such as photovoltaics.
In contrast, roll-to-roll processing of thin flexible substrates allows for the use of compact, less expensive vacuum systems, and of non-specialized equipment that already has been developed for other thin film industries. PV cells based on thin flexible substrate materials also exhibit a relatively high tolerance to rapid heating and cooling and to large thermal gradients (resulting in a low likelihood of fracture or failure during processing), require comparatively low shipping costs, and exhibit a greater ease of installation than cells based on rigid substrates. Additional details relating to the composition and manufacture of thin film PV cells of a type suitable for use with the presently disclosed methods and apparatus may be found, for example, in U.S. Pat. Nos. 6,310,281, 6,372,538, and 7,194,197, all to Wendt et al. These patents are hereby incorporated into the present disclosure by reference for all purposes.
As noted previously, a significant number of PV cells often are connected in series to achieve a usable voltage, and thus a desired power output. Such a configuration is often called a “string” of PV cells. Due to the different properties of crystalline substrates and flexible thin film substrates, the electrical series connection between cells may be constructed differently for a thin film cell than for a crystalline cell, and forming reliable series connections between thin film cells poses several challenges. For example, soldering (the traditional technique used to connect crystalline solar cells) directly on thin film cells exposes the PV coatings of the cells to damaging temperatures, and the organic-based silver inks typically used to form a collection grid on thin film cells may not allow strong adherence by ordinary solder materials in any case. Thus, PV cells often are joined with wires or conductive tabs attached to the cells with an electrically conductive adhesive (ECA), rather than by soldering.
However, even when wires or tabs are used to form inter-cell connections, the extremely thin coatings and potential flaking along cut PV cell edges introduces opportunities for shorting (power loss) wherever a wire or tab crosses over a cell edge. Furthermore, the conductive substrate on which the PV coatings are deposited, which typically is a metal foil, may be easily deformed by thermo-mechanical stress from attached wires and tabs. This stress can be transferred to weakly-adhering interfaces, which can result in delamination of the cells. In addition, adhesion between the ECA and the cell back side, or between the ECA and the conductive grid on the front side, can be weak, and mechanical stress may cause separation of the wires or tabs at these locations. Also, corrosion can occur between the molybdenum or other coating on the back side of a cell and the ECA that joins the tab to the solar cell there. This corrosion may result in a high-resistance contact or adhesion failure, leading to power losses.
Advanced methods of joining thin film PV cells with conductive tabs or ribbons may largely overcome the problems of electrical shorting and delamination, but may require undesirably high production costs to do so. Furthermore, all such methods—no matter how robust—require that at least some portion of the PV string be covered by a conductive tab, which blocks solar radiation from striking that portion of the string and thus reduces the efficiency of the system. As a result, there is a need for improved methods of interconnecting PV cells into strings, and for improved strings of interconnected cells. Specifically, there is a need for strings and methods of their formation that reduce interconnection costs and reduce the fraction of each PV cell that is covered by the interconnection mechanism, while maintaining or improving the ability of the cell to withstand stress.
SUMMARYPhotovoltaic module configurations 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. Modules may also have a back sheet for protection. The back sheet may also have a conductive pattern which is connected at selected locations to the top sheet grid establishing electrical interconnection between opposite sides of adjacent cells.
Methods of manufacturing photovoltaic modules including integrated multi-cell interconnections are also described. Methods include steps of coordinating, integrating, and registering multiple rolls of substrates in a continuous process. A photovoltaic web material may be cut to provide partially singulated cell regions. Singulation of discrete cells may later be carried out by trimming edge portions after the web has been laminated to another continuous sheet of material.
Methods of producing a building integrated photovoltaic (BIPV) product, and methods of installing a BIPV product are also described. A BIPV product including a laminated module package containing plural interconnected photovoltaic cells may be provided in roll form. The laminated module may also have a conductive return line parallel to the string of cells. The module may be configured to allow an installer to cut an appropriate strip from the roll for a specific building feature, for example, a stretch of roof. The installer may then apply an electrical connection from the last cell in the string, to the return line, providing positive and negative connection contacts on the same end, side, or proximity of the module.
Numerous other devices, intermediate articles, methods of manufacture, and methods of BIPV installation will be apparent from the detailed description below and related figures.
Systems and methods of interconnecting thin-film photovoltaic cells in a flexible substrate package may include a series of photovoltaic cells and a transparent top sheet covering the cells. Electrically-conductive pathways are established connecting a “sunny” side of one cell to the back side of an adjacent cell. One or more holes or “vias” may be provided in a given cell for providing an electrical connection from a conductive grid on the top side of a cell to a back side of an adjacent cell. Additional methods and apparatus for interconnecting flexible, thin-film photovoltaic (PV) cells in a scalable, efficient process, are provided. More specifically, examples of the present teachings relate to a roll-to-roll assembly of flexible PV cells on a flexible current-carrying back sheet. The back sheet may be a conductive substrate on which photovoltaic materials have been deposited. Alternatively a current carrying back sheet may include an insulating substrate having a conductive grid pattern deposited on one side. The resulting assembly may be particularly well suited for building integrated photovoltaic (BIPV) applications, such as installation onto the roof or side of a building. A current-carrying back sheet may include a metalized pattern that provides one or more of the following features, among others: (1) facilitating PV cell interconnection, (2) providing a “return line” to transfer power produced by a module of interconnected cells to a desired location, (3) providing a test area allowing PV cells to be tested prior to final installation, and/or (4) providing an attachment area to simplify installation of a module, for example, on a roof or other exterior surface of a building.
After cutting holes as shown in
Independently from preparation of web 100 as shown in
As shown in
In a final stage of assembling the photovoltaic module into a packaged product configuration, for example, a building integrated photovoltaic (BIPV) product, terminal tape 184 which is selected to be nonconducting and protective, is placed over return line 158 and over exposed contacts or test areas 180. It may also be desirable to create partially cut out regions 188 on return line 158 and test areas 180.
An entire module including the portion shown in
As shown in the figures, back sheet grid 154 includes relatively large or expansive conduits compared to grid strips in grid 124 on the top side of the module. Grid strips on the front of the module must be relatively thin to allow sufficient transmissive area for sun to reach the photovoltaic cells. In contrast, there is no similar need for the back sheet with grid pattern to be transmissive. Accordingly, back sheet grid 154 uses relatively wide conduits which may decrease resistance.
In a subsequent or parallel step 316, a transmissive front sheet is prepared with a metalized, conductive, grid pattern applied on one side. The grid pattern includes sub-patterns corresponding to cell regions which were partially singulated in step 308. Next, in step 318, the front sheet is applied to the PV web, aligning the grid with cell regions, and with the vias cut in step 308. Edges of the PV web are then trimmed 322 to complete singulation of the PV cells.
In a subsequent or parallel set of steps 326, a back sheet is prepared having a metalized connection pattern. In step 330, electrically conductive adhesive (ECA) is applied over the vias on the underside of the PV web. In step 334 the back sheet is applied to the PV web and the front sheet forming a laminated package or module in which individual photovoltaic cells are interconnected in series, and protected between laminated front and back sheets. Step 338 involves testing cells by contacting exposed contact areas on the individual cells. Step 338 may be carried out during the manufacturing process prior to completing lamination of the entire package. After testing 338, terminal tape may be applied 342 to cover cell contacts and a return line which may, optionally, be provided in the PV module.
In a subsequent or parallel set of steps, a front sheet is prepared 716 with metal collection grid and interconnect zones. Then dielectric strips are applied 720 over portions of the grid on the front sheet. Subsequently, the front sheet is joined 724 to the PV web. Interconnect tabs on the grid of the front sheet are registered with respect to interconnect zones or pads on the PV web material. Next, the edge regions of the photovoltaic web are trimmed 728 to complete singulation of discrete cells. Finally, electrically conductive adhesive (ECA) or ultrasonic welding is used to connect 732 interconnection tabs of the grid on the front sheet, to the back contact pads of the PV web, thus establishing electrical interconnection between opposite sides of adjacent cells. A protective back sheet may then be applied on the back side of the PV web for protective purposes.
The methods described above and shown in
The method illustrated in
While the concepts discussed above have been described primarily in the context of flexible substrates having thin film CIGS photovoltaic layers, it should be understood that many of the concepts may also be readily used advantageously with other thin film devices and processes, for example, based on cadmium telluride, as well as rigid silicon based photovoltaic devices.
The various structural members disclosed herein may be constructed from any suitable material, or combination of materials, such as metal, plastic, nylon, rubber, or any other materials with sufficient structural strength to withstand the loads incurred during use. Materials may be selected based on their durability, flexibility, weight, and/or aesthetic qualities.
It is believed that the following claims particularly point out certain combinations and subcombinations that are directed to one of the disclosed inventions and are novel and non-obvious. Inventions embodied in other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different invention or directed to the same invention, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the inventions of the present disclosure.
Claims
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.
Type: Application
Filed: Dec 28, 2010
Publication Date: Jan 5, 2012
Applicant: GLOBAL SOLAR ENERGY, INC. (Tucson, AZ)
Inventors: Scott Wiedeman (Tucson, AZ), Jeffrey S. Britt (Tucson, AZ), Zulima Rhodes (Tucson, AZ), Eric Sheehan (Tucson, AZ)
Application Number: 12/980,201
International Classification: H01L 31/05 (20060101); H01L 31/042 (20060101); H01L 31/18 (20060101); B32B 3/10 (20060101);