Tandem photovoltaic devices and methods for testing and use of photovoltaic systems

Abstract

Tandem photovoltaic devices and strings of photovoltaic devices can include structural configurations to facilitate improved diagnostic testing and provide module-level bypass. Also provided are methods of performing diagnostic tests.

Description

TANDEM PHOTOVOLTAIC DEVICES AND METHODS FOR TESTING AND USE OFPHOTOVOLTAIC SYSTEMSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 622,922, filed on January 19, 2024, which is incorporated by reference herein in its entirety.BACKGROUND

[0002] A photovoltaic device generates electrical power by converting light into electricity using semiconductor materials that exhibit the photovoltaic effect. Certain semiconductor materials are more efficient at absorbing particular ranges of the electromagnetic spectrum. To improve the overall efficiency of photovoltaic devices, the devices can incorporate stacked submodules, also referred to as subcells, utilizing semiconductor materials with differing absorptive properties to form a tandem photovoltaic device.

[0003] In an example tandem photovoltaic device, solar radiation or light enters through a top submodule and a portion of the radiation passes through the top submodule to a bottom submodule. The top submodule can absorb more higher-energy photons having a shorter wavelength, while the bottom submodule can absorb lower energy photons having a longer wavelength received through the top submodule. In a bifacial tandem device, the bottom submodule can receive both indirect light, received through the top submodule, and light reflected from the ground or other exterior surfaces.

[0004] However, multiple submodules can cause difficulties when performing diagnostic operations for a tandem photovoltaic device. In particular, it can be difficult to determine if a problem is associated with the entire device or stems solely from an individual submodule.

[0005] In addition, difficulties can arise when connecting multiple photovoltaic devices in a string of photovoltaic devices connected in series. Namely, if one device or module of the string of photovoltaic devices is shaded, the affected device or module can function as a resistor and be overly heated, which can result in degradation of the affected device or module and prevent current flow for power generation by the entire string of photovoltaic devices.

[0006] Accordingly, a need exists for improved electrical connections for tandem photovoltaic devices and strings having a plurality of photovoltaic devices.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 schematically depicts a cross-sectional view of a tandem photovoltaic device according to one or more embodiments shown and described herein.

[0008] FIG. 2 schematically depicts a circuit diagram of a tandem photovoltaic device according to one or more embodiments shown and described herein.

[0009] FIG. 3 schematically depicts a circuit diagram of a tandem photovoltaic device according to one or more embodiments shown and described herein.

[0010] FIG. 4 schematically depicts a first submodule of a tandem photovoltaic device according to one or more embodiments shown and described herein.

[0011] FIG. 5 schematically depicts a second submodule of a tandem photovoltaic device according to one or more embodiments shown and described herein.

[0012] FIG. 6 schematically depicts a back side of a tandem photovoltaic device according to one or more embodiments shown and described herein.

[0013] FIG. 7 schematically depicts a back side of a tandem photovoltaic device according to one or more embodiments shown and described herein.

[0014] FIG. 8 schematically depicts a cross-sectional view of a tandem photovoltaic device according to one or more embodiments shown and described herein.

[0015] FIG. 9 schematically depicts a set of photovoltaic devices connected in series and arranged in a string.

[0016] FIG. 10 schematically depicts a tandem photovoltaic device with terminals located on the side of the tandem photovoltaic device.

[0017] The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the drawings, wherein like reference numerals designate corresponding parts throughout the views.DETAILED DESCRIPTION

[0018] The present technology relates to tandem photovoltaic devices that include a first submodule and a second submodule; however, it should be recognized that such tandem photovoltaic devices can include additional submodules as well as additional arrangements of submodules. It is noted that the term “submodule” can include different types of photovoltaic devices, for example, but not limited to, photovoltaic devices including one or more thin films, one or more wafers, or combinations thereof. The tandem photovoltaic device can generate electrical power by converting light into direct current electricity using semiconductor materials that exhibit the photovoltaic effect. It is noted that the term “light” can refer to various wavelengths of the electromagnetic spectrum such as, but not limited to, wavelengths in the ultraviolet (U V), infrared (IR), and visible portions of the electromagnetic spectrum. “Sunlight,” as used herein, refers to light emitted by the sun. The photovoltaic effect generates electrical power upon exposure to light as photons are absorbed within the semiconductor material to excite electrons to a higher energy state. These excited electrons can move within the material, resulting in an electrical current. Semiconductor materials suitable for use in photovoltaic devices can include, for example, type II- VI materials - including cadmium telluride alloys, type III-V materials - including GaAs and InGaN, type I-III-VI materials - including CIGS and CIS materials, as well as silicon, and perovskites.

[0019] Tandem photovoltaic devices can achieve higher total conversion efficiency than single photovoltaic devices by capturing a larger portion of the solar spectrum. Tandem devices can be formed with more than one p-n junction and with materials having different band-gap properties responsive to different ranges of the electromagnetic spectrum, including infrared, visible, and ultraviolet light. In a device for which the primary light source is from above, a lightincident top cell, or upper submodule, can have a large band gap to capture energetic short wavelengths, such as visible and ultraviolet, while a bottom cell, or lower submodule, can use absorber materials having a smaller band gap to capture longer wavelengths and reflected photons, including near-infrared. A tandem device can have two or more stacked sub-cells or submodules, and each submodule can include active regions formed from semiconductor materials having different absorptive properties, including different types of semiconductor materials.

[0020] Since tandem devices have two or more stacked sub-cells or submodules, which can have different absorptive properties and / or semiconductor materials, diagnostic testing can be more difficult. For example, it can be difficult to isolate a particular submodule during a diagnostic test. Generally, the tandem photovoltaic devices provided herein can include design features configured to facilitate improved diagnostic testing. In particular’, the design features can enable an operator to test the combined submodules as a whole or isolate an individual submodule during a diagnostic test. Various embodiments of the tandem photovoltaic device, as well as strings and methods for performing diagnostic tests will be described in more detail herein.

[0021] With reference to FIG. 1, an embodiment of a tandem photovoltaic device 300 is shown. The tandem photovoltaic device 300 can be configured to receive light and transform light into electrical energy, as photons are absorbed from the light and transformed into electrical current by the photovoltaic effect. For sake of discussion and clarity, the tandem photovoltaic device 300 can define a front side 302 configured to face a primary light source such as, for example, the sun. Additionally, the tandem photovoltaic device 300 can also define a back side 304 offset from the front side 302 such as, for example, by a plurality of functional layers of material.

[0022] As shown in FIG. 1, the tandem photovoltaic device 300 can have a first submodule 100, a second submodule 500, and a dielectric layer 400 therebetween. The first submodule 100 can also be termed a top cell or upper submodule. The second submodule 500 can also be termed a bottom cell or lower submodule. Each of the first submodule 100, the second submodule 500, and the dielectric layer 400 can comprise a plurality of layers. As used herein, the term “layer” refers to a thickness of material provided upon a surface. Each layer can cover all or a portion of the surface. Each of the first and second submodules 100, 500 of the tandem photovoltaic device 300 can include one or more absorber layers for converting light into charge carriers, and conductive layers for collecting the charge carriers. In certain examples, one or both of the first and second submodules 100, 500 include one or more wafers encompassed by dielectric.

[0023] While still referring to FIG. 1, the first submodule 100 can have a first surface 102 substantially facing the front side 302 of the tandem photovoltaic device 300 and a second surface 104 substantially facing the back side 304 of the tandem photovoltaic device 300. The dielectric layer 400 can have a first surface 402 substantially facing the front side 302 of the tandem photovoltaic device 300 and a second surface 404 substantially facing the back side 304 of thetandem photovoltaic device 300. The second submodule 500 can have a first surface 502 substantially facing the front side 302 of the tandem photovoltaic device 300 and a second surface 504 substantially facing the back side 304 of the tandem photovoltaic device 300.

[0024] As depicted in FIG. 1, incident light ( / iv) 10 can enter the front side 302 of the tandem photovoltaic device 300 through the first submodule 100 and a first portion of light energy can be absorbed by the first submodule 100 and a remaining portion of light energy can pass through the first submodule 100 to the second submodule 500. Optionally, in a bifacial tandem device, back side light energy 16 can enter the back side 304 of the tandem photovoltaic device 300 toward the second submodule 500.

[0025] The first submodule 100 can include a plurality of layers disposed between the first surface 102 and the second surface 104. The plurality of layers can include a substrate, a transparent layer, a barrier layer, a transparent conductive oxide layer, a buffer layer, an absorber layer, a back contact layer, a conducting layer, or combinations thereof. The absorber layer can include type II- VI materials - including cadmium telluride alloys, type IILV materials - including GaAs and InGaN, type I- III- VI materials - including CIGS and CIS materials, as well as silicon, and perovskites, or combinations thereof.

[0026] With reference to FIG. 4, the layers of the first submodule 100 can be divided into a first plurality of electrically connected cells 106. The first plurality of electrically connected cells 106 can be operable to convert optical energy into a first submodule voltage across a first submodule positive bus 108 and a first submodule negative bus 110, as shown in FIGS. 2-3. The cells of the first plurality of electrically connected cells 106 can be electrically connected in series or in parallel. For example, the cells can be connected in series to increase the total voltage, or the cells can be connected in parallel to increase the total current. With reference to FIG. 4, the first plurality of electrically connected cells 106 includes a first cell 106a, a second cell 106b, a third cell 106c, and a fourth cell 106d connected in parallel across three first submodule positive buses 108a, 108b, 108c and two first submodule negative buses 110a, 110b. The number of cells and buses are scalable according to the desired voltage and current requirements.

[0027] With reference to FIG. 1, submodules in a tandem photovoltaic device 300, as described herein, can be stacked, and separated by the dielectric layer 400. For example, the dielectric layer 400 can be disposed over the first submodule 100 and between the first submodule100 and the second submodule 500. The dielectric layer 400 can include a dielectric material such as, for example, a photoresist material or a non-conductivc polymer. Suitable example dielectric material can further include epoxy, acrylic, phenolic, polyimide, or the like.

[0028] The second submodule 500 can include a plurality of layers disposed between the first surface 502 and the second surface 504. The plurality of layers can include a substrate, a transparent layer, a barrier layer, a transparent conductive oxide layer, a buffer layer, an absorber layer, a back contact layer, a conducting layer, or combinations thereof. The absorber layer can include type II- VI materials - including cadmium telluride alloys, type III-V materials - including GaAs and InGaN, type I- III- VI materials - including CIGS and CIS materials, as well as silicon, and perovskites, or combinations thereof.

[0029] With reference to FIG. 5, the layers of the second submodule 500 can be divided into a second plurality of electrically connected cells 506. The second plurality of electrically connected cells 506 can be operable to convert optical energy into a second submodule voltage across a second submodule positive bus 508 and a second submodule negative bus 510, as shown in FIGS. 2-3. The cells of the second plurality of electrically connected cells 506 can be electrically connected in series or in parallel. For example, the cells can be connected in series to increase the total voltage, or the cells can be connected in parallel to increase the total current. In the illustrated example, the second plurality of electrically connected cells 506 includes one or more cells connected in series between a second submodule positive bus 508 and a second submodule negative bus 510. The number of cells and buses are scalable according to the desired voltage and current requirements.

[0030] While still referring to FIGS. 2-3, the first submodule 100 and the second submodule 500 can be connected in parallel. The second submodule positive bus 508 can be electrically connected to a first terminal 308 on the tandem photovoltaic device 300. In certain examples, the second submodule positive bus 508 includes a first conductive member 310, for example, conductive foil or ribbon, which connects the second submodule positive bus 508 to the first terminal 308, as shown in FIG. 8. With reference to FIG. 6, the first terminal 308 can be located on a side of the tandem photovoltaic device 300, including, but not limited to, the back side 304 of the tandem photovoltaic device 300. In other examples, the first terminal 308 can be located on an edge of the tandem photovoltaic device 300, for example, as shown in FIG. 10.

[0031] With reference to FIGS. 2-3, the first submodule positive bus 108 can be electrically connected to a second terminal 312 on the tandem photovoltaic device 300. In certain examples, the first submodule positive bus 108 includes a second conductive member 314, for example, foil, which connects the first submodule positive bus 108 to the second terminal 312. As shown in FIG. 8, the three first submodule positive busses can be electrically connected to the second terminal 312 on the tandem photovoltaic device 300 by the second conductive member 314.

[0032] With reference to FIG. 6, the second terminal 312 can be located on a side of the tandem photovoltaic device 300, including, but not limited to the back side 304 of the tandem photovoltaic device 300. In other examples, the second terminal 312 can be located on an edge of the tandem photovoltaic device 300, for example, as shown in FIG. 10. The second terminal 312 can be located adjacent to the first terminal 308.

[0033] Referring now to FIG. 8, the second conductive member 314 can include a first self-lapping section 316. A first portion 314a of the second conductive member 314 contacts a second portion 314b of the conductive member at the first self-lapping section 316. In other words, the first self-lapping section 316 is where one portion of the second conductive member 314 contacts another portion of the second conductive member 314. In certain examples, the first portion 314a of the second conductive member 314 contacts the second portion 314b of the conductive member in such a way that the first self-lapping section 316 defines a loop. The first self-lapping section 316 can be flexed into different shapes, as desired, for example, semicircles, ovals, etc. As shown in the illustrated example, the first submodule positive bus 108 is electrically connected to the second terminal 312 on the tandem photovoltaic device 300 by the first selflapping section 316. While still referring to FIG. 8, one 108a of the three first submodule positive buses can be electrically connected to the first portion 314a of the second conductive member 314 and a second one of the three positive submodule busses is connected to the second portion 314b of the second conductive member 314.

[0034] With reference to FIGS. 2-3, the first submodule negative bus 110 and the second submodule negative bus 510 can be electrically connected to a third terminal 318 on the tandem photovoltaic device 300. In certain examples, the first submodule negative bus 110 and the second submodule negative bus 510 include a third conductive member 320, for example, foil, which connects the first submodule negative bus 110 and the second submodule negative bus 510 to thethird terminal 318. As shown in FTG. 6, the third terminal 318 can be located on a side of the tandem photovoltaic device 300, including, but not limited to the back side 304 of the tandem photovoltaic device 300. In other examples, the third terminal 318 can be located on an edge of the tandem photovoltaic device 300, for example, as shown in FIG. 10. With reference to the illustrated example in FIG. 8, the two first submodule negative buses 110a, 110b can be electrically connected to the third terminal 318 with the second submodule negative bus 510.

[0035] With reference to FIGS. 2-3, the first submodule positive bus 108 can be electrically connected to a fourth terminal 322 on the tandem photovoltaic device 300. In certain examples, the first submodule positive bus 108 includes the second conductive member 314, for example, foil, which connects the first submodule positive bus 108 to the fourth terminal 322. As shown in the illustrated example in FIG. 8, the three first submodule positive busses can be electrically connected to the fourth terminal 322 on the tandem photovoltaic device 300 by the second conductive member 314.

[0036] With reference to FIG. 6, the fourth terminal 322 can be located on a side of the tandem photovoltaic device 300, including, but not limited to the back side 304 of the tandem photovoltaic device 300. In other examples, the fourth terminal 322 can be located on an edge of the tandem photovoltaic device 300, for example, as shown in FIG. 10. The fourth terminal 322 can be located adjacent to the third terminal 318.

[0037] Referring now to FIG. 8, the second conductive member 314 can include a second self-lapping section 324. The second portion 314b of the second conductive member 314 contacts a third portion 314c of the conductive member at the second self-lapping section 324. In other words, the second self-lapping section 324 is where one portion of the second conductive member 314 contacts another portion of the second conductive member 314. In certain examples, the second portion 314b of the second conductive member 314 contacts the third portion 314c of conductive member in such a way that the second self-lapping section 324 defines a loop. The second self-lapping section 324 can be flexed into different shapes, as desired, for example, semicircles, ovals, etc. As shown in the illustrated example, the first submodule positive bus 108 is electrically connected to the fourth terminal 322 on the tandem photovoltaic device 300 by the second self-lapping section 324. While still referring to FIG. 8, one 108a of the three first submodule positive buses can be electrically connected to the first portion 314a of the secondconductive member 314, a second one 108b of the three positive submodule busses is connected to the second portion 314b of the second conductive member 314; and a third one 108c of the three first submodule positive buses can be electrically connected to the third portion 314c of the second conductive member 314.

[0038] With reference to the examples illustrated in FIGS. 1-9, the electrically conductive components, including bussing, electrical leads, and conductive members, can include electrical insulation. As non-limiting examples, the conductive members 310, 314, 320, may include conductive foil, wire, tape, or ribbon.

[0039] Advantageously, the aforementioned configuration enables an operator to perform a diagnostic test for the first submodule 100, the second submodule 500, or both submodules in tandem. For example, a method for performing a diagnostic test for the first submodule 100 comprises connecting a first lead of a multimeter to the second terminal 312; connecting a second lead of the multimeter to the third terminal 318; and conducting a flash test. As used herein, the term multimeter can include different electrical measurement and / or diagnostic devices, for example, but not limited to, a voltmeter, ammeter, ohmmeter, electroluminescence measurement devices, or combinations thereof. The flash test can comprise applying a high-intensity flash of light to the tandem photovoltaic device 300 and measuring the response in terms of voltage and current. The measured results can then be compared to the expected voltage and current to determine if the first submodule 100 is functioning properly. For instance, the method can further include a step of identifying non-conforming modules by comparing the measured results with the expected voltage and current. Desirably, since the second terminal 312 is connected to the first submodule positive bus 108 and the third terminal 318 is connected to the first submodule negative bus 110, the method allows an operator to isolate the measurements to the first submodule during the flash test. This can also allow for easier and more accurate pre-deployment testing (including before a junction box is installed on the tandem photovoltaic device 300).

[0040] In another example, a method for performing a diagnostic test for the second submodule 500 comprises connecting the first lead of the multimeter to the first terminal 308; connecting the second lead of the multimeter to the third terminal 318; and conducting the flash test. The measured results can then be compared to the expected voltage and current to determine if the second submodule 500 is functioning properly. For instance, the method can further includea step of identifying non-conforming modules by comparing the measured results with the expected voltage and current. Desirably, since the first terminal 308 is in electrical communication with the second submodule positive bus 508 and the third terminal 318 is in electrical communication with the second submodule negative bus 510, the method enables an operator to isolate the measurements to the second submodule 500 during the flash test. This can also allow for easier and more accurate pre-deployment testing (including before a junction box is installed on the tandem photovoltaic device 300).

[0041] In another example, a method for performing a diagnostic test for the combined first submodule 100 and the second submodule 500 comprises contacting the first lead of the multimeter to the first terminal 308 and the second terminal 312; contacting the second lead of the multimeter to the third terminal 318; and conducting the flash test. The measured results can then be compared to the expected voltage and current to determine if the combined first submodule 100 and the second submodule 500 is functioning as expected. For instance, the method can further include a step of identifying non-conforming modules by comparing the measured results with the expected voltage and current. Desirably, since the first lead is connected to the both the first terminal 308 and the second terminal 312, which are connecting to the second submodule positive bus 508 and the first submodule positive bus 108, respectively, and the second lead is connected to the third terminal 318, which is in electrical communication with both the first submodule negative bus 110 and the second submodule negative bus 510, the measurements during the flash test can be inclusive of both the first submodule 100 and the second submodule 500. This can also allow for easier and more accurate pre-deployment testing (including before a junction box is installed on the tandem photovoltaic device 300).

[0042] It should be appreciated that the photovoltaic devices and methods can also facilitate other diagnostic testing. In one example, a method for performing a diagnostic test for the first submodule 100 includes connecting a first lead of a power supply to the second terminal 312; connecting a second lead of the power supply to the third terminal 318; and conducting an electroluminescence health diagnostic verification test. In another example, a method for performing a diagnostic test for the second submodule 500 includes connecting the first lead of the power supply to the first terminal 308; connecting the second lead of the power supply to the third terminal 318; and conducting an electroluminescence health diagnostic verification test.

[0043] With reference to FIGS 3, and 7, the tandem photovoltaic device 300 can further comprise a positive junction box 326. The positive junction box 326 can be disposed on a side, for example, but not limited to, the back side 304 of the tandem photovoltaic device 300, or an edge of the tandem photovoltaic device 300, for example, where the terminals 308, 312 are shown in FIG. 10. In an example, the positive junction box 326 is disposed over the first terminal 308 and the second terminal 312, as shown in FIG. 7. The first terminal 308 and the second terminal 312 can be electrically connected to a common positive terminal 328 in the positive junction box 326. Advantageously, the positive junction box 326 enables for a single positive connection from the photovoltaic device to the other components of the solar power generation system.

[0044] With reference to 3 and 7, the tandem photovoltaic device 300 can further comprise a negative junction box 330. The negative junction box 330 can be disposed on a side, for example, but not limited to, the back side 304 of the tandem photovoltaic device 300, or an edge of the tandem photovoltaic device 300, for example, where the terminals 318, 322 are shown in FIG. 10. In an example, the negative junction box 330 is disposed over the third terminal 318 and the fourth terminal 322, as shown in FIG. 7. The third terminal 318 can be electrically connected to a common negative terminal 332 in the negative junction box 330. The fourth terminal 322 can be electrically connected to the common negative terminal 332 by a reverse bypass diode 334, as shown in FIG. 3. Advantageously, the negative junction box 330 provides a single negative connection from the photovoltaic device to the other components of the solar power generation system, while also incorporating the reverse bypass diode 334 to allow for a module level bypass. This can eliminate the need for a separate junction box for the reverse bypass diode 334, which saves resources and reduces complexity.

[0045] With reference to FIG. 3, the reverse bypass diode 334 can have a first diode terminal 336 forming an electrical connection with the fourth terminal 322 and a second diode terminal 338 forming an electrical connection with the third terminal 318. When the tandem photovoltaic device 300 is electrically connected to an array of photovoltaic devices, the reverse bypass diode 334 can substantially block a reverse current from flowing through the reverse bypass diode 334 when the tandem photovoltaic device 300 receives sunlight. The reverse bypass diode 334 functions as an open switch during reverse bias. When the tandem photovoltaic device 300 is shaded, the tandem photovoltaic device 300 behaves like a semiconductive resistor and forward biases the reverse bypass diode 334 diverting current away from the tandem photovoltaic device300 to another photovoltaic device 300. The reverse bypass diode 334 functions as a closed switch during forward bias.

[0046] With reference to FIG. 9, a string of photovoltaic devices 600 includes a plurality of the tandem photovoltaic devices 300. In the illustrated embodiment, the tandem photovoltaic devices 300 are connected to together in series. As an example, a string for use in a small-scale or residential power generation system can have 2 to 20 tandem photovoltaic devices 300 in the string of photovoltaic devices 600. In another example of a small-scale power generation system, the number of tandem photovoltaic devices 300 in the string of photovoltaic devices 600 can be in a range from 2 to 10 tandem photovoltaic devices.

[0047] Advantageously, the reverse bypass diode 334 provides a current path around a tandem photovoltaic device 300 in the event the device becomes faulty or open-circuited. Use of the reverse bypass diode 334 enables the string of photovoltaic devices 600 to continue supplying power rather than no power at all. During normal sunny operation, the reverse bypass diode 334 can substantially block a reverse current from flowing through the reverse bypass diode 334. When one of the tandem photovoltaic devices becomes shaded and / or damaged, the reverse bypass diode 334 provides an alternate path for the current around the shaded and / or damaged tandem photovoltaic devices to allow the string to have a complete circuit. In addition, the reverse bypass diode 334 also prevents the current from tandem photovoltaic devices 300 that are working (at high potential) to flow back to the faulty panel (at low potential). Thus, even when one of the tandem photovoltaic devices 300 is faulty, the string can still produce electricity. When the shading condition is removed, or the power generation restored to the previously-faulty device, the diode resumes its operation of substantially blocking a reverse current from flowing through the reverse bypass diode 334. This configuration can be especially useful in residential or mixed-use environments where shading events are more frequent than in systems designed for large-scale power plant energy production. The reverse bypass diode is also beneficial in systems of all sizes where maintenance availability is limited or infrequent.

[0048] According to the embodiments provided herein, a tandem photovoltaic device can comprise a first submodule, a dielectric layer, and a second submodule. The first submodule comprises a first plurality of electrically connected cells operable to convert optical energy into a first voltage across a first submodule positive bus and a first submodule negative bus. Thedielectric layer is disposed over the first submodule. The second submodule is disposed over the dielectric layer. The second submodule comprises a second plurality of electrically connected cells operable to convert optical energy into a second voltage across a second submodule positive bus and a second submodule negative bus. The first submodule positive bus comprises a conductive member having a first self-lapping section. A first portion of the conductive member contacts a second portion of the conductive member at the first self-lapping section.

[0049] According to another embodiment provided herein, a method for performing a diagnostic test for the first submodule comprises: connecting a first lead of a multimeter to the second terminal; connecting a second lead of a multimeter to the third terminal; and conducting a flash test.

[0050] According to another embodiment provided herein, a method for performing a diagnostic test for the second submodule comprises: connecting a first lead of a multimeter to the first terminal; connecting a second lead of multimeter to the third terminal; and conducting a flash test.

[0051] According to another embodiment provided herein, a method for performing a diagnostic test for the tandem photovoltaic device comprises: connecting a first lead of a multimeter to the first terminal and the second terminal; connecting a second lead of a multimeter to the third terminal; and conducting a flash test.

[0052] According to another embodiment provided herein, a method for performing a diagnostic test for the tandem photovoltaic device comprises: connecting a first lead of a multimeter to common positive terminal; connecting a second lead of a multimeter to the common negative terminal; and conducting a flash test.

[0053] According to the embodiments provided herein, a tandem photovoltaic device comprises a first submodule, a dielectric layer, and a second submodule. The first submodule comprises a first plurality of electrically connected cells operable to convert optical energy into a first voltage across a first submodule positive bus and a first submodule negative bus. The dielectric layer is disposed over the first submodule. The second submodule is disposed over the dielectric layer. The second submodule comprises a second plurality of electrically connected cells operable to convert optical energy into a second voltage across a second submodule positive bus and a second submodule negative bus. The first submodule positive bus comprises aconductive member having a first self-lapping section and a second self-lapping section. A first portion of the conductive member contacts a second portion of the conductive member at the first self-lapping section. The second portion of the conductive member contacts a third portion of the conductive member at the second self-lapping section.

[0054] According to the embodiments provided herein, tandem photovoltaic device comprises a first submodule, a dielectric layer, and a second submodule. The first submodule comprises a first plurality of electrically connected cells operable to convert optical energy into a first voltage across a first submodule positive bus and a first submodule negative bus. The dielectric layer is disposed over the first submodule. The second submodule is disposed over the dielectric layer. The second submodule comprises a second plurality of electrically connected cells operable to convert optical energy into a second voltage across a second submodule positive bus and a second submodule negative bus. The first submodule positive bus comprises a conductive member having a first self-lapping section and a second self-lapping section. The first portion of the conductive member contacts a second portion of the conductive member at the first self-lapping section. The second portion of the conductive member contacts a third portion of the conductive member at the second self-lapping section. The second submodule positive bus is electrically connected to a first terminal on the tandem photovoltaic device. The first submodule positive bus is electrically connected to a second terminal on the tandem photovoltaic device by the first self-lapping section. The first submodule negative bus and the second submodule negative bus are electrically connected to a third terminal. The first submodule positive bus is electrically connected to a fourth terminal on the tandem photovoltaic device by the second self-lapping section.

[0055] According to the embodiments provided herein, a method for performing a diagnostic test for a tandem photovoltaic device having a first submodule and a second submodule comprises connecting a first lead of a multimeter to a second terminal; connecting a second lead of a multimeter to a third terminal; and conducting a flash test. The second terminal is electrically connected to a first self-lapping section electrically connected to a first submodule positive bus of the first submodule. The third terminal is electrically connected to a first submodule negative bus of the first submodule and a second submodule negative bus of the second submodule.

[0056] According to the embodiments provided herein, a method for performing a diagnostic test for a tandem photovoltaic device having a first submodule and a second submodule comprises connecting a first lead of a multimeter to a first terminal; connecting a second lead of a multimeter to a third terminal; and conducting a flash test. The first terminal is electrically connected to a second submodule positive bus of the second submodule. The third terminal is electrically connected to a first submodule negative bus of the first submodule and a second submodule negative bus of the second submodule.

[0057] It is noted that the terms "substantially" and "about" may be utilized herein to represent the inherent degree of uncertainty that may be attributed to a quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0058] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.

Claims

CLAIMSWhat is claimed is:

1. A tandem photovoltaic device comprising: a first submodule comprising a first plurality of electrically connected cells operable to convert optical energy into a first voltage across a first submodule positive bus and a first submodule negative bus; a dielectric layer disposed over the first submodule; and a second submodule disposed over the dielectric layer, the second submodule comprising a second plurality of electrically connected cells operable to convert optical energy into a second voltage across a second submodule positive bus and a second submodule negative bus, wherein the first submodule positive bus comprises a conductive member having a first self-lapping section, and a first portion of the conductive member contacts a second portion of the conductive member at the first self-lapping section.

2. The tandem photovoltaic device of claim 1, wherein the second submodule positive bus is electrically connected to a first terminal on the tandem photovoltaic device.

3. The tandem photovoltaic device of claim 2, wherein the first terminal is on a side or edge of the tandem photovoltaic device.

4. The tandem photovoltaic device of claim 2, wherein the first submodule positive bus is electrically connected to a second terminal on the tandem photovoltaic device by the first selflapping section.

5. The tandem photovoltaic device of claim 4, wherein the second terminal is on a side or edge of the tandem photovoltaic device.

6. The tandem photovoltaic device of claim 4, further comprising a positive junction box disposed on tandem photovoltaic device, wherein the first terminal and the second terminal are electrically connected to a common positive terminal in the positive junction box.

7. The tandem photovoltaic device of claim 6, wherein the positive junction box is disposed over the first terminal and the second terminal.

8. The tandem photovoltaic device of claim 4, wherein the first submodule negative bus and the second submodule negative bus are electrically connected to a third terminal.

9. The tandem photovoltaic device of claim 8, wherein the third terminal is on a side or edge of the tandem photovoltaic device on the tandem photovoltaic device.

10. The tandem photovoltaic device of claim 8, wherein the conductive member of the first submodule positive bus has a second self-lapping section, and the second portion of the conductive member contacts a third portion of the conductive member at the second self-lapping section.

11. The tandem photovoltaic device of claim 10, wherein the first submodule positive bus is electrically connected to a fourth terminal on the tandem photovoltaic device by the second selflapping section.

12. The tandem photovoltaic device of claim 11, wherein the fourth terminal is on a side or edge of the tandem photovoltaic device on the tandem photovoltaic device.

13. The tandem photovoltaic device of claim 11, further comprising a negative junction box disposed on tandem photovoltaic device, wherein the third terminal and the fourth terminal are connected to separate terminals of a bypass diode in the negative junction box, and the third terminal is electrically connected to a common negative terminal in the negative junction box.

14. The tandem photovoltaic device of claim 13, wherein the negative junction box is disposed over the third terminal and the fourth terminal.

15. The tandem photovoltaic device of claim 11, further comprising a positive junction box and a negative junction box disposed on tandem photovoltaic device, wherein the first terminaland the second terminal are electrically connected to a common positive terminal in the positive junction box, and wherein the third terminal and the fourth terminal arc connected to separate terminals of a bypass diode in the negative junction box, and the third terminal is electrically connected to a common negative terminal in the negative junction box.

16. The tandem photovoltaic device of claim 1, wherein the first plurality of electrically connected cells are connected to each other in parallel.

17. The tandem photovoltaic device of claim 1, wherein the second plurality of electrically connected cells are connected to each other in series.

18. A method for performing a diagnostic test for the first submodule of claim 8, the method comprising: connecting a first lead of a multimeter to the second terminal; connecting a second lead of the multimeter to the third terminal; and conducting a flash test.

19. A method for performing a diagnostic test for the first submodule of claim 8, the method comprising: connecting a first lead of a power supply to the second terminal; connecting a second lead of the power supply to the third terminal; and conducting an electroluminescence health diagnostic verification test.

20. A method for performing a diagnostic test for the second submodule of claim 8, the method comprising: connecting a first lead of a multimeter to the first terminal; connecting a second lead of the multimeter to the third terminal; and conducting a flash test.

21. A method for performing a diagnostic test for the second submodule of claim 8, the method comprising:connecting a first lead of a power supply to the first terminal; connecting a second lead of the power supply to the third terminal; and conducting an electroluminescence health diagnostic verification test.

22. A string of tandem photovoltaic devices comprising the tandem photovoltaic device of claim 1.

23. The string of tandem photovoltaic of claim 22, wherein the string of tandem photovoltaic devices includes 2-10 of tandem photovoltaic devices.

24. A method for performing a diagnostic test for the tandem photovoltaic device of claim 8, the method comprising: connecting a first lead of a multimeter to the first terminal and the second terminal; connecting a second lead of a multimeter to the third terminal; and conducting a flash test.

25. A method for performing a diagnostic test for the tandem photovoltaic device of claim 15, the method comprising: connecting a first lead of a multimeter to common positive terminal; connecting a second lead of a multimeter to the common negative terminal; and conducting a flash test.

26. A tandem photovoltaic device comprising: a first submodule comprising a first plurality of electrically connected cells operable to convert optical energy into a first voltage across a first submodule positive bus and a first submodule negative bus; a dielectric layer disposed over the first submodule; and a second submodule disposed over the dielectric layer, the second submodule comprising a second plurality of electrically connected cells operable to convert optical energy into a second voltage across a second submodule positive bus and a second submodule negative bus, wherein the first submodule positive bus comprises a conductive member having a firstself-lapping section and a second self-lapping section, a first portion of the conductive member contacts a second portion of the conductive member at the first self-lapping section, and the second portion of the conductive member contacts a third portion of the conductive member at the second self-lapping section.

27. A tandem photovoltaic device comprising: a first submodule comprising a first plurality of electrically connected cells operable to convert optical energy into a first voltage across a first submodule positive bus and a first submodule negative bus; a dielectric layer disposed over the first submodule; and a second submodule disposed over the dielectric layer, the second submodule comprising a second plurality of electrically connected cells operable to convert optical energy into a second voltage across a second submodule positive bus and a second submodule negative bus, wherein the first submodule positive bus comprises a conductive member having a first self-lapping section and a second self-lapping section, a first portion of the conductive member contacts a second portion of the conductive member at the first self-lapping section, and the second portion of the conductive member contacts a third portion of the conductive member at the second self-lapping section, and wherein: the second submodule positive bus is electrically connected to a first terminal on the tandem photovoltaic device, the first submodule positive bus is electrically connected to a second terminal on the tandem photovoltaic device by the first self-lapping section, the first submodule negative bus and the second submodule negative bus are electrically connected to a third terminal, and the first submodule positive bus is electrically connected to a fourth terminal on the tandem photovoltaic device by the second self-lapping section.

28. A method for performing a diagnostic test for a tandem photovoltaic device having a first submodule and a second submodule, the method comprising: connecting a first lead of a multimeter to a second terminal, wherein the second terminalis electrically connected to a first self-lapping section electrically connected to a first submodule positive bus of the first submodule; connecting a second lead of a multimeter to a third terminal, wherein the third terminal is electrically connected to a first submodule negative bus of the first submodule and a second submodule negative bus of the second submodule; and conducting a flash test.

29. A method for performing a diagnostic test for a tandem photovoltaic device having a first submodule and a second submodule, the method comprising: connecting a first lead of a multimeter to a first terminal, wherein the first terminal is electrically connected to a second submodule positive bus of the second submodule; connecting a second lead of multimeter to a third terminal, wherein the third terminal is electrically connected to a first submodule negative bus of the first submodule and a second submodule negative bus of the second submodule; and conducting a flash test.

30. A tandem photovoltaic device comprising: a first submodule comprising a first plurality of electrically connected cells operable to convert optical energy into a first voltage across a first submodule positive bus and a first submodule negative bus; and a second submodule disposed over the dielectric layer, the second submodule comprising a second plurality of electrically connected cells operable to convert optical energy into a second voltage across a second submodule positive bus and a second submodule negative bus, wherein the first submodule positive bus comprises a conductive member having a first self-lapping section, and a first portion of the conductive member contacts a second portion of the conductive member at the first self-lapping section.

31. The tandem photovoltaic device of claim 30, wherein a dielectric layer is disposed over the first submodule.

32. The tandem photovoltaic device of any of claims 30 or 31 , wherein the second submodule positive bus is electrically connected to a first terminal on the tandem photovoltaic device.

33. The tandem photovoltaic device of claim 32, wherein the first terminal is on a side or edge of the tandem photovoltaic device.

34. The tandem photovoltaic device of claim 32, wherein the first submodule positive bus is electrically connected to a second terminal on the tandem photovoltaic device by the first selflapping section.

35. The tandem photovoltaic device of claim 34, wherein the second terminal is on a side or edge of the tandem photovoltaic device.

36. The tandem photovoltaic device of claim 34, further comprising a positive junction box disposed on tandem photovoltaic device, wherein the first terminal and the second terminal are electrically connected to a common positive terminal in the positive junction box.

37. The tandem photovoltaic device of claim 36, wherein the positive junction box is disposed over the first terminal and the second terminal.

38. The tandem photovoltaic device of claim 4, wherein the first submodule negative bus and the second submodule negative bus are electrically connected to a third terminal.

39. The tandem photovoltaic device of claim 38, wherein the third terminal is on a side or edge of the tandem photovoltaic device on the tandem photovoltaic device.

40. The tandem photovoltaic device of claim 38, wherein the conductive member of the first submodule positive bus has a second self-lapping section, and the second portion of the conductive member contacts a third portion of the conductive member at the second self-lapping section.

41. The tandem photovoltaic device of claim 40, wherein the first submodule positive bus is electrically connected to a fourth terminal on the tandem photovoltaic device by the second selflapping section.

42. The tandem photovoltaic device of claim 41, wherein the fourth terminal is on a side or edge of the tandem photovoltaic device on the tandem photovoltaic device.

43. The tandem photovoltaic device of claim 41, further comprising a negative junction box disposed on tandem photovoltaic device, wherein the third terminal and the fourth terminal are connected to separate terminals of a bypass diode in the negative junction box, and the third teiminal is electrically connected to a common negative terminal in the negative junction box.

44. The tandem photovoltaic device of claim 43, wherein the negative junction box is disposed over the third terminal and the fourth terminal.

45. The tandem photovoltaic device of claim 41, further comprising a positive junction box and a negative junction box disposed on tandem photovoltaic device, wherein the first terminal and the second terminal are electrically connected to a common positive terminal in the positive junction box, and wherein the third terminal and the fourth terminal are connected to separate terminals of a bypass diode in the negative junction box, and the third terminal is electrically connected to a common negative terminal in the negative junction box.

46. The tandem photovoltaic device of any of claims 30-45, wherein the first plurality of electrically connected cells are connected to each other in parallel.

47. The tandem photovoltaic device of any of claims 30-45, wherein the second plurality of electrically connected cells are connected to each other in series.

48. A method for performing a diagnostic test for the first submodule of claim 38, the method comprising:connecting a first lead of a multimeter to the second terminal; connecting a second lead of the multimeter to the third terminal; and conducting a flash test.

49. A method for performing a diagnostic test for the first submodule of claim 38, the method comprising: connecting a first lead of a power supply to the second terminal; connecting a second lead of the power supply to the third terminal; and conducting an electroluminescence health diagnostic verification test.

50. A method for performing a diagnostic test for the second submodule of claim 38, the method comprising: connecting a first lead of a multimeter to the first terminal; connecting a second lead of the multimeter to the third terminal; and conducting a flash test.

51. A method for performing a diagnostic test for the second submodule of claim 38, the method comprising: connecting a first lead of a power supply to the first terminal; connecting a second lead of the power supply to the third terminal; and conducting an electroluminescence health diagnostic verification test.

52. A string of tandem photovoltaic devices comprising the tandem photovoltaic device of any of claims 30-52.

53. The string of tandem photovoltaic of claim 52, wherein the string of tandem photovoltaic devices includes 2-10 of tandem photovoltaic devices.

54. A method for performing a diagnostic test for the tandem photovoltaic device of claim 38, the method comprising: connecting a first lead of a multimeter to the first terminal and the second terminal;connecting a second lead of a multimeter to the third terminal; and conducting a flash test.

55. A method for performing a diagnostic test for the tandem photovoltaic device of claim 45, the method comprising: connecting a first lead of a multimeter to common positive terminal; connecting a second lead of a multimeter to the common negative terminal; and conducting a flash test.

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