WO2020097041A1

WO2020097041A1 - Sawtooth solar module

Info

Publication number: WO2020097041A1
Application number: PCT/US2019/059811
Authority: WO
Inventors: Timothy James Orsley
Original assignee: Corning Incorporated
Priority date: 2018-11-07
Filing date: 2019-11-05
Publication date: 2020-05-14
Also published as: TW202029635A

Abstract

A sawtooth solar module includes at least one solar cell segment; and a top glass cover positioned atop a top surface of the at least one solar cell segment, such that the at least one solar cell segment includes at least two triangularly-shaped compartments, a reflector positioned at the interface of the at least two triangularly-shaped compartments, and a solar cell extending from and perpendicular to the top glass cover along an edge of the first triangularly-shaped compartment.

Description

SAWTOOTH SOLAR MODULE

BACKGROUND

1. Field

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S.

Provisional Application Serial No. 62/756,820 filed on November 7, 2018, the content of which is relied upon and incorporated herein by reference in its entirety.

[0002] The disclosure relates to sawtooth solar modules.

2. Technical Background

[0003] Solar modules are single photovoltaic panels that are assemblies of connected solar cells. The solar cells absorb sunlight as a source of energy to generate electricity.

[0004] Conventional solar modules often completely cover their exposed area with solar cells and protect the solar cells with glass, as shown in FIG. 1. These traditional solar modules generally require use of large amounts of solar material, thereby resulting in higher costs and lower effective capacity in manufacturing facilities.

[0005] This disclosure presents improved solar modules and uses thereof.

SUMMARY

[0006] In some embodiments, a sawtooth solar module, comprises: at least one solar cell segment; and a top glass cover positioned atop a top surface of the at least one solar cell segment, wherein the at least one solar cell segment comprises: a first triangularly-shaped compartment and a second triangularly-shaped compartment, a reflector positioned at the interface of the first triangularly-shaped compartment and the second triangularly-shaped compartment, and a solar cell extending from and perpendicular to the top glass cover along an edge of the first triangularly-shaped compartment.

[0007] In one aspect, which is combinable with any of the other aspects or embodiments, the first triangularly- shaped compartment comprises a first material with a first refractive index in a range of 1.0 to 1.8. [0008] In one aspect, which is combinable with any of the other aspects or embodiments, the first refractive index is in a range of 1.30 to 1.45.

[0009] In one aspect, which is combinable with any of the other aspects or embodiments, the first material comprises a mixture of glycol and water.

[00010] In one aspect, which is combinable with any of the other aspects or embodiments, the second triangularly-shaped compartment comprises a second material with a second refractive index in a range of 1.0 to 1.5.

[00011] In one aspect, which is combinable with any of the other aspects or embodiments, the second refractive index is in a range of 1.0 to 1.33.

[00012] In one aspect, which is combinable with any of the other aspects or embodiments, the second material comprises air or a mixture of glycol and water.

[00013] In one aspect, which is combinable with any of the other aspects or embodiments, the first triangularly- shaped compartment comprises a first material with a first refractive index; the second triangularly-shaped compartment comprises a second material with a second refractive index; and the first refractive index is greater than or equal to the second refractive index.

[00014] In one aspect, which is combinable with any of the other aspects or embodiments, the sawtooth solar module further comprises: a plurality of solar cell segments, wherein the reflector in the plurality of solar cell segments is unidirectional.

[00015] In one aspect, which is combinable with any of the other aspects or embodiments, a ratio between a height of the solar cell to a width of the at least one solar cell segment is in a range of 0.25: 1 to 0.50: 1.

[00016] In one aspect, which is combinable with any of the other aspects or embodiments, the ratio is in a range of 0.30: 1 to 0.40: 1.

[00017] In one aspect, which is combinable with any of the other aspects or embodiments, the reflector comprises at least one layer of aluminum (Al), silver (Ag), or aluminized Mylar.

[00018] In one aspect, which is combinable with any of the other aspects or embodiments, the top glass cover is configured for total internal reflection of light rays.

[00019] In one aspect, which is combinable with any of the other aspects or embodiments, the sawtooth solar module further comprises: a bottom glass cover positioned atop a bottom surface of the at least one solar cell segment, wherein the solar cell extends perpendicular to the bottom glass cover.

[00020] In one aspect, which is combinable with any of the other aspects or embodiments, the top glass cover and the bottom glass cover are each independently selected from an alkali-free glass or an alkali-containing glass.

[00021] In one aspect, which is combinable with any of the other aspects or embodiments, the first triangularly-shaped compartment comprises a first material, when the first material has a refractive index niA, an angle Q_IA is between the solar cell and the reflector, when the first material has a refractive index ni_B, an angle Q_IB is between the solar cell and the reflector, when ni_A is greater than n , Q_IA is greater than Q_IB, when ¾A is less than n , Q_IA is less than Q_IB, and when niA is equal to niB, QIA is equal to QIB.

[00022] In one aspect, which is combinable with any of the other aspects or embodiments, the sawtooth solar module further comprises: a plurality of solar cell segments, such that the first triangularly-shaped compartment comprises a first material, when the first material has a refractive index niA, the plurality of solar cell segments comprises XIA segments, when the first material has a refractive index ni_B, the plurality of solar cell segments comprises XIB segments, when ni_A is greater than nm, XIA is less than XIB, when ¾A is less than nm, XIA is greater than XIB, when ¾A is equal to e, XIA is equal to XIB.

[00023] In one aspect, which is combinable with any of the other aspects or embodiments, the reflector is a dual-sided reflector configured to reflect light rays from both a top reflector surface and a bottom reflector surface.

[00024] In some embodiments, a sawtooth solar module, comprises: at least one solar cell segment; and a top glass cover positioned atop a top surface of the at least one solar cell segment, wherein the at least one solar cell segment comprises: at least two triangularly-shaped compartments, a reflector positioned at the interface of the at least two triangularly-shaped compartments, and a solar cell extending from and perpendicular to the top glass cover along an edge of a first triangularly- shaped compartment.

[00025] In one aspect, which is combinable with any of the other aspects or embodiments, the sawtooth solar module further comprises: a plurality of solar cell segments, wherein the solar cell is positioned at an interface of each of the plurality of solar cell segments. [00026] In one aspect, which is combinable with any of the other aspects or embodiments, the at least two triangularly-shaped compartments comprise the first triangularly-shaped compartment, a second triangularly-shaped compartment, and a third triangularly-shaped compartment, and the reflector comprises a first reflector positioned at the interface of the first triangularly-shaped compartment and the second triangularly-shaped compartment, and a second reflector positioned at the interface of the third triangularly-shaped compartment and the second triangularly-shaped compartment.

[00027] In one aspect, which is combinable with any of the other aspects or embodiments, the first reflector converges to the second reflector along a surface of the top glass cover.

[00028] In one aspect, which is combinable with any of the other aspects or embodiments, the first triangularly-shaped compartment and the third triangularly-shaped compartment comprise a first material with a first refractive index in a range of 1.0 to 1.8.

[00029] In one aspect, which is combinable with any of the other aspects or embodiments, the first refractive index is in a range of 1.30 to 1.45.

[00030] In one aspect, which is combinable with any of the other aspects or embodiments, the first material comprises a mixture of glycol and water.

[00031] In one aspect, which is combinable with any of the other aspects or embodiments, the second triangularly-shaped compartment comprises a second material with a second refractive index in a range of 1.0 to 1.5.

[00032] In one aspect, which is combinable with any of the other aspects or embodiments, the second refractive index is in a range of 1.0 to 1.33.

[00033] In one aspect, which is combinable with any of the other aspects or embodiments, the second material comprises air or a mixture of glycol and water.

[00034] In one aspect, which is combinable with any of the other aspects or embodiments, the first triangularly-shaped compartment and the third triangularly-shaped compartment comprise a first material with a first refractive index; the second triangularly-shaped compartment comprises a second material with a second refractive index; and the first refractive index is greater than or equal to the second refractive index. [00035] In one aspect, which is combinable with any of the other aspects or embodiments, a ratio between a height of the solar cell to a width of the at least one solar cell segment is in a range of 0.25: 1 to 0.50: 1.

[00036] In one aspect, which is combinable with any of the other aspects or embodiments, the ratio is in a range of 0.30: 1 to 0.40: 1.

[00037] In one aspect, which is combinable with any of the other aspects or embodiments, the reflector comprises at least one layer of aluminum (Al), silver (Ag), or aluminized Mylar.

[00038] In one aspect, which is combinable with any of the other aspects or embodiments, the top glass cover is configured for total internal reflection of light rays.

[00039] In one aspect, which is combinable with any of the other aspects or embodiments, the sawtooth solar module further comprises: a bottom glass cover positioned atop a bottom surface of the at least one solar cell segment, wherein the solar cell extends perpendicular to the bottom glass cover.

[00040] In one aspect, which is combinable with any of the other aspects or embodiments, the top glass cover and the bottom glass cover are each independently selected from an alkali-free glass or an alkali-containing glass.

BRIEF DESCRIPTION OF THE DRAWINGS

[00041] The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, in which:

[00042] FIG. 1 illustrates a traditional solar module configuration.

[00043] FIG. 2 illustrates a solar module configuration, according to some embodiments.

[00044] FIG. 3 illustrates a solar module configuration, according to some embodiments.

[00045] FIG. 4 illustrates sunlight ray configuration in Phoenix, according to some embodiments.

[00046] FIG. 5 illustrates a unidirectional solar cell module configuration, according to some embodiments.

[00047] FIGS. 6 and 7 illustrate bidirectional solar cell module configurations, according to some embodiments. [00048] FIG. 8 illustrates a perspective view of a unidirectional solar cell module configuration, according to some embodiments.

[00049] FIG. 9 illustrates average efficiency degradation over time for solar modules constructed with Eagle glass top and bottom covers and soda lime glass top and bottom covers, according to some embodiments.

DETAILED DESCRIPTION

[00050] Reference will now be made in detail to exemplary embodiments which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. The components in the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the exemplary embodiments. It should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting.

[00051] Additionally, any examples set forth in this specification are illustrative, but not limiting, and merely set forth some of the many possible embodiments of the claimed invention. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the field, and which would be apparent to those skilled in the art, are within the spirit and scope of the disclosure.

[00052] The present disclosure addresses the deficiencies of conventional solar modules by using a combination of reflectors within the module and trapping light entering the module by total internal reflection at glass/air interfaces, according to some embodiments. As a result, the solar modules disclosed herein are able to generate at least similar amounts of power as conventional solar modules while significantly reducing solar cell material in the design.

[00053] Turning to FIG. 2, a solar module 200 is disclosed, according to some embodiments, comprising at least one solar cell segment 201; and a top glass cover 202 positioned atop a top surface of the at least one solar cell segment 201. Furthermore, the at least one solar cell segment 201 comprises: a first triangularly-shaped compartment 208 and a second triangularly- shaped compartment 206, a reflector 210 positioned at the interface of the first triangularly- shaped compartment 208 and the second triangularly-shaped compartment 206, and a solar cell 212 extending from and perpendicular to the top glass cover 202 along an edge of the first triangularly-shaped compartment 208.

[00054] In some examples, the first triangularly-shaped compartment 208 comprises a first material with a first refractive index in a range of 1.0 to 1.8. For example, the first refractive index may be 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75,

1.8, or any intervening value, or any range therebetween. In some examples, the first refractive index is in a range of 1.30 to 1.45. For example, the first refractive index may be 1.30, 1.31,

1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.40, 1.41, 1.42, 1.43, 1.44, 1.45, or any intervening value, or any range therebetween. In some examples, the first material comprises a mixture of glycol and water. For example, the first material comprises a mixture having a glycol-to- water ratio of 0: 100, 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85: 15, 90: 10, 95:5, 100:0, or any intervening ratio therebetween.

[00055] In some examples, the second triangularly-shaped compartment 206 comprises a second material with a second refractive index in a range of 1.0 to 1.5. For example, the second refractive index may be 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, or any intervening value, or any range therebetween. In some examples, the second refractive index is in a range of 1.0 to 1.33. For example, the second refractive index may be 1.0, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.30, 1.31, 1.32, 1.33, or any intervening value, or any range therebetween. In some examples, the second material comprises air. In some examples, the second material comprises a mixture of glycol and water having a glycol-to-water ratio as described above for the first material.

[00056] In some examples, the second triangularly-shaped compartment 206 may be a clear triangular transparent or translucent (e.g., plastic) extrusion spanning the length of the at least one solar cell segment 201. Inside this extrusion is the second material (e.g., air or a mixture of glycol and water). The first material is prevented from entering the cavity of the second compartment (or vice-versa, whereby the second material is prevented from entering the cavity of the first compartment) by flexible membrane caps on at least one end of second compartment. For example, in certain examples, the second material may expand as a result of applied heat and displace the membrane caps by pushing them inward into the second compartment cavity and compressing the first material. This flexibility prevents bowing or flexing of the top and bottom cover glasses to maintain the desired optical arrangement. In some examples, the bottom cover glass 204 may function as one wall of the extrusion such that the extrusion has two walls (e.g., one wall supporting the solar cell 212, one wall supporting the reflector 210).

[00057] In some examples, the first triangularly-shaped compartment 208 may be a clear triangular transparent or translucent (e.g., plastic) extrusion spanning the length of the at least one solar cell segment 201. Inside this extrusion is the first material (e.g., a mixture of glycol and water). The first material is prevented from entering the cavity of the second compartment (or vice-versa, whereby the second material is prevented from entering the cavity of the first compartment) by flexible membrane caps on at least one end of first compartment, as described above. In some examples, the top cover glass 202 may function as one wall of the extrusion such that the extrusion has two walls (e.g., one wall supporting the solar cell 212, one wall supporting the reflector 210).

[00058] In some examples, the extrusion (either of the second triangularly-shaped compartment 206, the first triangularly-shaped compartment 208, or both) may be a polymeric material (e.g., PMMA) bonded to the cover glass such that the polymeric material is positioned between the solar cell 212 and the first or second material and between the reflector 210 and the first or second material. In some examples, the polymeric material may also be positioned between the top or bottom cover glass and the first or second material. As disclosed herein, light rays 216 may be trapped by the extrusion through a combination of reflection off the reflector 210 and total internal reflection off the glass/air interface; this involves paths through the cover glass, first material, and extrusion (i.e., PMMA).

[00059] In some examples, the first triangularly-shaped compartment 208 comprises a first material with a first refractive index; the second triangularly- shaped compartment 206 comprises a second material with a second refractive index; and the first refractive index is greater than or equal to the second refractive index. In some examples, the solar module further includes a plurality of solar cell segments 201, wherein the reflector 210 in the plurality of solar cell segments is unidirectional. [00060] In some examples, a ratio between a height of the solar cell 212 to a width of the at least one solar cell segment 201 is in a range of 0.25: 1 to 0.50: 1. For example, the ratio may be 0.25: 1, 0.30: 1, 0.35: 1, 0.40: 1, 0.45: 1, 0.50: 1, or any intervening value, or any range

therebetween. In some examples, the ratio is in a range of 0.30: 1 to 0.40: 1. For example, the ratio may be 0.30: 1, 0.31 : 1, 0.32: 1, 0.33: 1, 0.34: 1, 0.35: 1, 0.36: 1, 0.37: 1, 0.38: 1, 0.39: 1, 0.40: 1, or any intervening value, or any range therebetween.

[00061] In some examples, the reflector 210 comprises at least one layer of aluminum (Al), silver (Ag), aluminized Mylar, or combinations thereof. In some examples, the reflector 210 is a dual-sided reflector configured to reflect light rays from both a top reflector surface and a bottom reflector surface. In some examples, the top glass cover 202 is configured for total internal reflection of light rays 216. In some examples, the module further comprises a bottom glass cover 204 positioned atop a bottom surface of the at least one solar cell segment 201, wherein the solar cell 212 extends perpendicular to the bottom glass cover 204. In some examples, the bottom glass cover 204 may be a non-transparent material, such a metal sheet.

[00062] In some examples, the solar module comprises a plurality of solar cell segments 201, with the total number of segments XN determined by the index of refraction of the first material (m) in the first triangularly-shaped compartment and the overall module size. Stated generally, the total number of segments in the solar module may be determined by the index of refraction of the material through which the entering light rays penetrate and propagate toward the solar cell. For example, in some instances, the first material has a refractive index ni_A and an angle QIA is between the solar cell 212 and the reflector 210. In other instances, the first material has a refractive index n and an angle QIB is between the solar cell 212 and the reflector 210.

[00063] When ni_A is greater than nm, then QIA will be greater than QIB, meaning that as refractive index of the first material increases from nm to ni_A, the angle qi will also increase from Oi_B to QIA. AS a result, there will be fewer solar cell segments needed in the module where refractive index is ni_A than when the refractive index is e to trap equivalent amounts of light (i.e., xi_A is less than XIB). Conversely, when ¾A is less than nm, then QIA will be less than QIB, meaning that as refractive index of the first material decreases from nm to ni_A, the angle qi will also decrease from QIB to QIA. AS a result, there will be more solar cell segments needed in the module where refractive index is ni_A than when the refractive index is ni_B to trap equivalent amounts of light (i.e., XIA is greater than XIB).

[00064] In some examples, the solar module 200 may also include a single or pair of spacers 214 to seal the plurality of solar cell segments 201. Spacers 214 may be a frame surrounding the perimeter of the module 200 to which the top glass cover 202 and bottom glass cover 204 are affixed. This frame may prevent the contents of the first triangularly- shaped compartment 208 from escaping. A second frame (not shown) may also be included to protect edges of the glass covers and to provide a location to clamp the module when attaching to a single axis tracker, for example.

[00065] Turning to FIGS. 2 and 3, solar modules, 200 and 300, are disclosed, according to some embodiments, comprising at least one solar cell segment, 201 and 301 ; and a top glass cover, 202 and 302, positioned atop a top surface of the at least one solar cell segment, wherein the at least one solar cell segment, comprises: at least two triangularly-shaped compartments, 206-208 and 306-308b, a reflector(s), 210, 3l 0a, and 310b, positioned at the interface of the at least two triangularly-shaped compartments, and a solar cell, 212 and 312, extending from and

perpendicular to the top glass cover along an edge of a first triangularly-shaped compartment, 208, 308a, and 308b.

[00066] In some examples, the solar module further comprises: a plurality of solar cell segments, 212 and 312, wherein the solar cell is positioned at an interface of each of the plurality of solar cell segments, 201 and 301.

[00067] In some examples, the at least two triangularly-shaped compartments comprise the first triangularly-shaped compartment 308a, a second triangularly-shaped compartment 306, and a third triangularly-shaped compartment 308b, and the reflector comprises a first reflector 3l0a positioned at the interface of the first triangularly-shaped compartment 308a and the second triangularly-shaped compartment 306, and a second reflector 310b positioned at the interface of the third triangularly-shaped compartment 308b and the second triangularly- shaped compartment 306.

[00068] In some examples, the first reflector 3l0a converges to the second reflector 3 lOb along a surface of the top glass cover 302. In some examples, a ratio between the first reflector 3 lOa length to the second reflector 3l0b length may be 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85: 15, 90: 10, 95:5, or any intervening value, or any range therebetween. In some examples, a ratio between the first reflector 3l0a length to the second reflector 310b length may be 50:50. In some examples, a ratio between the first reflector 3l0a length to the second reflector 310b length may be 70:30.

[00069] In some examples, the first triangularly-shaped compartment 308a and the third triangularly-shaped compartment 308b comprise the first material and the second triangularly- shaped compartment 306 comprises the second material, both of which are described herein. Moreover, the geometry, materials, and functionality of the individual portions of the solar module described in FIG. 3 may be similar as those described herein for FIG. 2, according to some embodiments. For example, the module further comprises a bottom glass cover 304 positioned atop a bottom surface of the at least one solar cell segment 301, wherein the solar cell 312 extends perpendicular to the bottom glass cover 304. In some examples, the bottom glass cover 304 may be a non-transparent material, such a metal or fiberglass sheet. In some examples, the solar module 300 may also include a single or pair of spacers 314 to seal the plurality of solar cell segments 301. Spacers 314 are analogous to spacers 214 in function and position.

EXAMPLES

[00070] The embodiments described herein will be further clarified by the following examples.

[00071] Unidirectional Sawtooth Solar Modules

[00072] Unidirectional solar modules disclosed herein may be those with the reflector facing in a single direction (FIG. 2). For example, FIG. 8 illustrates a perspective view of a unidirectional solar cell module configuration, according to some embodiments.

[00073] Optimal angle at which reflectors may be positioned depend on the latitude at which the solar module is deployed, as well as the north-south tilt of the modules at that location. In some examples, the modules may be assumed to not be tilted, at least initially. In some examples, tilt of the modules may be controlled via single axis (east-west) tracking, where modules track the position of the sun throughout the day. Thus, the modules remain parallel to the ground from a north-south perspective. [00074] With east-west tracking, the angle of the sun relative to the modules is a function of the latitude of the location and the season. For example, in Phoenix where the latitude is about 33.44°N, the sun on the summer solstice is 10° off normal (i.e., the difference between latitude and the 23.44° tilt of the earth) (see FIG. 4). By considering the highest position of the sun (e.g. in summer), a reflector may be positioned relative to a vertical strip of solar cells (e.g., qi from FIGS. 2 and 3) such that light rays either strike the solar cells directly or indirectly by reflecting off the reflector and/or the top glass cover/air interface through total internal reflection. Angles of reflection may depend at least on the season (see FIG. 5, for Phoenix). Aside from summer, when the sun is lower than its summer peak position, the sun is positionally lower in the sky, reaching its lowest point on the winter solstice at 56.88° off normal. At all such lower angles, the light rays continue to fall on the solar cells either directly or by reflection and because of this phenomenon, the particular reflector angle resulting in full illumination (less fractional losses from bounces off the reflector) sets the gap between cells. By comparing the distance between the solar cells to the height of the solar cells, the savings in solar cell material may be determined. In the case of Phoenix, this savings is 68.5% (with a refractive index of 1.5 in the first

triangularly-shaped compartment), meaning that the solar cell module design of FIG. 5 (and similarly, FIG. 2), results in about the same generation of solar cell energy as a traditional solar cell module (e.g., as in FIG. 1) while using 68.5% less solar cell material. Since reflector angle can be optimized for latitude, at higher latitudes, a greater amount of solar cell material savings is observed using unidirectional solar modules. Moreover, a reflector angle optimized for a certain latitude may also be fully efficient at higher latitudes, with some sacrifice in solar cell material savings.

[00075] Moreover, unidirectional solar modules may also allow for scattered light impinging upon the rear of the module (through the bottom glass cover) to generate power (i.e., backside illumination). In other words, the reflector is a dual-sided reflector configured to reflect light rays from both a top reflector surface and a bottom reflector surface.

[00076] Bidirectional Sawtooth Solar Modules

[00077] Bidirectional solar modules disclosed herein may be those with two reflectors in the same solar cell segment facing different directions (e.g., FIG. 3). Closer to the equator (i.e., lower latitudes), a greater amount of solar cell material savings may be accomplished using bidirectional solar modules. For example, at the equator, the solar cell module configuration may be as in FIG. 6 (50: 50 ratio between the north- facing reflector length to the south-facing reflector length), which experiences solar cell material savings at about 73% (with a refractive index of 1.5 in the first and third triangularly- shaped compartments) since the solar cells are able to absorb light from either direction (though generally, one side of the solar cell typically generates more power than the other side). In some examples, the side of the solar cell which comprises electrical interconnects generates about 80% of the power compared to the opposite side.

[00078] Bidirectional solar modules may also be used at higher latitudes as well, using optimized angles of the north-facing and south-facing reflectors depending on the particular location (i.e., latitude) to ensure total internal reflection (TIR). The angles of the reflectors vary at different latitudes. For example, as seen in FIG. 7 with the example of Phoenix, because of the low angle of the sun at winter solstice, the south-facing reflector must have a steeper angle than the north-facing reflector to form an approximately 70:30 ratio between the north-facing reflector length to the south-facing reflector length. This results in a 30% incremental solar cell material savings. With the configuration as in FIG. 7, the bidirectional solar module generates about 94% as much power as that of the unidirectional module due to an 80% efficiency of backside illumination.

[00079] Bidirectional solar modules may be especially attractive options in applications where power gain from backside illumination is limited because the underlying structure may block a portion of the module. For example, in residential applications, the underlying roof blocks the entire rear of the solar module, with only a small opportunity to illuminate the backside coming from the air gap created to help the solar cells run cooler and more efficiently. Commercial and industrial applications are similar to residential because modules are placed almost parallel to the roof with a ballast system which does not require penetrating the roof membrane and keeps wind loads down. In some examples, a non-transparent back sheet may substitute for the bottom glass cover.

[00080] Glass Covers

[00081] In some examples, the top glass cover and/or the bottom glass cover may use EAGLE XG^® glass (“Eagle”) from Corning, Inc. The Eagle glass is a boro-aluminosilicate, environmentally friendly glass containing no heavy metals (arsenic, antimony, barium, or halides) or alkalis and features high surface quality, excellent thermal properties, low density, and high resistance to chemicals.

[00082] The thinner Eagle glass may substantially reduce module weight (most of which is due to the cover glass), thereby providing a budget for the incremental material in the compartments. For example, modules may be fabricated using a 1.0 mm thick Eagle glass for both of the front and back covers versus traditional modules using 2.5 mm soda lime glass for the front and back covers.

[00083] Another benefit of Eagle glass is module lifetime. Conventional modules often suffer from potential induced degradation (PID) caused by alkali migration from the cover glass. Being alkali free, Eagle glass eliminates a root cause of PID. FIG. 9 illustrates average efficiency degradation over time for solar modules constructed with Eagle glass top and bottom covers and soda lime glass top and bottom covers, according to some embodiments. Efficiency degradation after 500-hour intervals were measured during which multi-cell modules were exposed to 85°C temperatures and 85% relative humidity with the solar cells biased at about -1000 V. The module comprising soda lime top and bottom cover glasses shorted completely during the initial 500-hour interval, while the modules comprising Eagle glass top and bottom covers showed no degradation after 3000 hours.

[00084] Advantages of the solar modules disclosed herein include: (1) a reduction in solar cell material used, resulting in budgets for features not in traditional modules (e.g., reflectors); (2) an increase in effective capacity of solar cell manufacturing facilities (i.e., due to reduced solar cell material usage in the modules described herein, the number of modules produced for equivalent amount of material consumed increases, versus that of conventional modules); and (3) solar cell configuration being orthogonal to the cover glass, rather than coplanar with the cover glass as in traditional modules, which increases mechanical robustness and allows for use of thinner cover glass materials such as Eagle glass to further reduce material weight and prevent potential induced degradation (i.e., the solar cells are micro-singulated and rest upon a flex circuit vertical to the cover glass such that the flex circuit can flex to prevent cracking in the micro-singulated solar cells). [00085] As utilized herein, the terms“approximately,”“about,”“substantially”, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

[00086] As utilized herein,“optional,”“optionally,” or the like are intended to mean that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not occur. The indefinite article“a” or“an” and its corresponding definite article“the” as used herein means at least one, or one or more, unless specified otherwise.

[00087] References herein to the positions of elements (e.g.,“top,”“bottom,”“above,”“below,” etc.) are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

[00088] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural

permutations may be expressly set forth herein for the sake of clarity.

[00089] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claimed subject matter.

Accordingly, the claimed subject matter is not to be restricted except in light of the attached claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A sawtooth solar module, comprising:

at least one solar cell segment; and

a top glass cover positioned atop a top surface of the at least one solar cell segment, wherein the at least one solar cell segment comprises:

a first triangularly-shaped compartment and a second triangularly-shaped compartment,

a reflector positioned at the interface of the first triangularly- shaped compartment and the second triangularly-shaped compartment, and

a solar cell extending from and perpendicular to the top glass cover along an edge of the first triangularly-shaped compartment.

2. The sawtooth solar module of claim 1, wherein the first triangularly-shaped compartment comprises a first material with a first refractive index in a range of 1.0 to 1.8.

3. The sawtooth solar module of claim 2, wherein the first refractive index is in a range of 1.30 to 1.45.

4. The sawtooth solar module of claim 2, wherein the first material comprises a mixture of glycol and water.

5. The sawtooth solar module of any one of claims 1-4, wherein the second triangularly- shaped compartment comprises a second material with a second refractive index in a range of 1.0 to 1.5.

6 The sawtooth solar module of claim 5, wherein the second refractive index is in a range of 1.0 to 1.33.

7. The sawtooth solar module of claim 5, wherein the second material comprises air or a mixture of glycol and water.

8. The sawtooth solar module of any one of claims 1-7, wherein:

the first triangularly-shaped compartment comprises a first material with a first refractive index;

the second triangularly-shaped compartment comprises a second material with a second refractive index; and

the first refractive index is greater than or equal to the second refractive index.

9. The sawtooth solar module of any one of claims 1-8, further comprising:

a plurality of solar cell segments,

wherein the reflector in the plurality of solar cell segments is unidirectional.

10. The sawtooth solar module of any one of claims 1-9, wherein a ratio between a height of the solar cell to a width of the at least one solar cell segment is in a range of 0.25: 1 to 0.50: 1.

11. The sawtooth solar module of claim 10, wherein the ratio is in a range of 0.30: 1 to 0.40: 1.

12. The sawtooth solar module of any one of claims 1-11, wherein the reflector comprises at least one layer of aluminum (Al), silver (Ag), or aluminized Mylar.

13. The sawtooth solar module of any one of claims 1-12, wherein the top glass cover is configured for total internal reflection of light rays.

14. The sawtooth solar module of any one of claims 1-13, further comprising:

a bottom glass cover positioned atop a bottom surface of the at least one solar cell segment,

wherein the solar cell extends perpendicular to the bottom glass cover.

15. The sawtooth solar module of claim 14, wherein the top glass cover and the bottom glass cover are each independently selected from an alkali-free glass or an alkali-containing glass.

16. The sawtooth solar module of any one of claims 1-15, wherein:

the first triangularly-shaped compartment comprises a first material,

when the first material has a refractive index niA, an angle Q_IA is between the solar cell and the reflector,

when the first material has a refractive index nm, an angle Q_IB is between the solar cell and the reflector,

when ni_A is greater than n , Q_IA is greater than Q_IB,

when niA is less than nm, QIA is less than QIB, and

when niA is equal to nm, QIA is equal to 0m.

17. The sawtooth solar module of any one of claims 1-16, further comprising:

a plurality of solar cell segments,

wherein:

the first triangularly-shaped compartment comprises a first material, when the first material has a refractive index niA, the plurality of solar cell segments comprises XIA segments,

when the first material has a refractive index nm, the plurality of solar cell segments comprises xm segments,

when niA is greater than nm, XIA is less than xm,

when niA is less than nm, XIA is greater than xm,

when niA is equal to nm, XIA is equal to xm.

18. The sawtooth solar module of any one of claims 1-17, wherein the reflector is a dual sided reflector configured to reflect light rays from both a top reflector surface and a bottom reflector surface.

19. A sawtooth solar module, comprising: at least one solar cell segment; and

at least two triangularly- shaped compartments,

a reflector positioned at the interface of the at least two triangularly- shaped compartments, and

a solar cell extending from and perpendicular to the top glass cover along an edge of a first triangularly-shaped compartment.

20. The sawtooth solar module of claim 19, further comprising:

a plurality of solar cell segments,

wherein the solar cell is positioned at an interface of each of the plurality of solar cell segments.

21. The sawtooth solar module of claim 19 or claim 20, wherein:

the at least two triangularly-shaped compartments comprise the first triangularly-shaped compartment, a second triangularly-shaped compartment, and a third triangularly-shaped compartment, and

the reflector comprises a first reflector positioned at the interface of the first triangularly- shaped compartment and the second triangularly- shaped compartment, and a second reflector positioned at the interface of the third triangularly-shaped compartment and the second triangularly-shaped compartment.

22. The sawtooth solar module of claim 21, wherein the first reflector converges to the second reflector along a surface of the top glass cover.

23. The sawtooth solar module of claim 21 or claim 22, wherein the first triangularly-shaped compartment and the third triangularly-shaped compartment comprise a first material with a first refractive index in a range of 1.0 to 1.8.

24. The sawtooth solar module of claim 23, wherein the first refractive index is in a range of 1.30 to 1.45.

25. The sawtooth solar module of claim 23 or claim 24, wherein the first material comprises a mixture of glycol and water.

26. The sawtooth solar module of any one of claims 21-25, wherein the second triangularly- shaped compartment comprises a second material with a second refractive index in a range of 1.0 to 1.5.

27. The sawtooth solar module of claim 26, wherein the second refractive index is in a range of 1.0 to 1.33.

28. The sawtooth solar module of claim 26 or claim 27, wherein the second material comprises air or a mixture of glycol and water.

29. The sawtooth solar module of claim 21, wherein:

the first triangularly-shaped compartment and the third triangularly-shaped compartment comprise a first material with a first refractive index;

30. The sawtooth solar module of any one of claims 19-29, wherein a ratio between a height of the solar cell to a width of the at least one solar cell segment is in a range of 0.25: 1 to 0.50: 1.

31. The sawtooth solar module of claim 30, wherein the ratio is in a range of 0.30: 1 to 0.40: 1.

32. The sawtooth solar module of any one of claims 19-31 , wherein the reflector comprises at least one layer of aluminum (Al), silver (Ag), or aluminized Mylar.

33. The sawtooth solar module of any one of claims 19-32, wherein the top glass cover is configured for total internal reflection of light rays.

34. The sawtooth solar module of any one of claims 19-33, further comprising:

wherein the solar cell extends perpendicular to the bottom glass cover.

35. The sawtooth solar module of claim 34, wherein the top glass cover and the bottom glass cover are each independently selected from an alkali-free glass or an alkali-containing glass.