Solar cell module

A solar cell module includes: a first solar cell; a second solar cell disposed apart from the first solar cell with a space therebetween; a first light reflector disposed on an edge portion of the first solar cell, and overlapping the space; and a second light reflector disposed on an edge portion of the second solar cell, and overlapping the space.

BACKGROUND

1. Technical Field

The present disclosure relates to a solar cell module.

2. Description of the Related Art

In recent years, solar cell modules have been progressively developed as photoelectric conversion devices which convert light energy into electric energy. Solar cell modules can directly convert inexhaustible sunlight into electricity, and thus have less environmental impact and generate power more cleanly than power generation using fossil fuels. Accordingly, such solar cell modules are expected to provide new energy sources.

For example, a solar cell module has a structure in which solar cells are sealed by a filling member, between a front surface shield and a back surface shield. In the solar cell module, the solar cells are disposed in a matrix. Pairs of adjacent solar cells among solar cells linearly aligned in either the row direction or the column direction are connected by tab lines to form a string.

Conventionally, a solar cell module has been proposed in which in order to effectively use sunlight emitted on the space between solar cells, a light reflector projecting out from the light-receiving surfaces of the solar cells and inclined relative to the light-receiving surfaces is provided in the space between the solar cells (for example, Japanese Unexamined Patent Application Publication No. 2013-98496).

SUMMARY

However, a conventional solar cell module often has difficulty in appropriately disposing a light reflector in the space between two adjacent solar cells since, for instance, the width of the space between two adjacent solar cells partially varies. The effects of improvement in efficiency of power generation achieved by the use of the light reflector will be thus diminished.

The present disclosure provides a solar cell module which effectively improves efficiency of power generation, using light reflectors.

In order to provide such a solar cell module, a solar cell module according to an aspect of the present disclosure includes: a first solar cell; a second solar cell disposed apart from the first solar cell with a space therebetween; a first light reflector disposed on an edge portion of the first solar cell, and overlapping the space; and a second light reflector disposed on an edge portion of the second solar cell, and overlapping the space.

The light reflectors effectively improve efficiency of power generation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following describes embodiments of the present disclosure with reference to the drawings. The embodiments described below each illustrate a particular example of the present disclosure. Thus, the numerical values, shapes, materials, elements, the arrangement and connection of the elements, processes, the order in which the processes are performed, and others indicated in the following embodiments are mere examples, and are not intended to limit the present disclosure. Therefore, among the elements in the following embodiments, elements not recited in any of the independent claims defining the most generic concept of the present disclosure are described as arbitrary elements.

The drawings are schematic diagrams and do not necessarily give strict illustration. Throughout the drawings, the same sign is given to the same element, and redundant description is omitted or simplified.

[Configuration of Solar Cell Module]

The first describes a schematic configuration of solar cell module1according to an embodiment, with reference toFIGS. 1, 2A, and 2B.FIG. 1is a plan view of solar cell module1according to the embodiment.FIGS. 2A and 2Bare cross-sectional views of solar cell module1according to the embodiment taken along line IIA-IIA and line IIB-IIB inFIG. 1.

Note that inFIGS. 1, 2A, and 2B, the Z axis is perpendicular to the principal surface of solar cell module1, and the X axis and the Y axis are orthogonal to each other, and are both orthogonal to the Z axis. The same applies to the Z axis, the X axis, and the Y axis in the drawings described below.

As illustrated inFIGS. 1, 2A, and 2B, solar cell module1includes solar cells10, tab lines20, light reflectors30, front surface shield40, back surface shield50, filling member60, and frame70. Solar cell module1has a structure in which solar cells10are sealed by filling member60between front surface shield40and back surface shield50.

As illustrated inFIG. 1, the shape of solar cell module1in a plan view is substantially quadrilateral, for example. As an example, solar cell module1has a substantially quadrilateral shape having a width of about 1600 mm, and a length of about 800 mm. Note that the shape of solar cell module1is not limited to a quadrilateral.

The following describes in further detail components of solar cell module1, with reference toFIGS. 3, 4, 5A, and 5B, and alsoFIGS. 1, 2A, and 2B.FIG. 3is a partial enlarged cross sectional view of solar cell module1according to the embodiment, illustrating enlarged region Y surrounded by the dashed line inFIG. 2A.FIG. 4is a partial enlarged plan view of solar cell module1according to the embodiment, illustrating enlarged region X surrounded by the dashed line inFIG. 1.FIGS. 5A and 5Bare enlarged cross sectional views of solar cell module1according to the embodiment taken along line VA-VA and line VB-VB inFIG. 4, respectively. Note thatFIG. 5Aillustrates a structure around tab lines20, andFIG. 5Billustrates a structure around light reflectors30.

Solar cell10is a photoelectric conversion element (photovoltaic element) which converts light such as sunlight into power. As illustrated inFIG. 1, solar cells10are disposed in rows and columns (a matrix) in the same plane.

Pairs of adjacent solar cells10among solar cells10linearly aligned in either the row direction or the column direction are connected by tab lines to form a string (cell string). Solar cells10are formed into a string by being electrically connected by tab lines20. Solar cells10in one string10S are connected in series by tab lines20.

As illustrated inFIG. 1, in the present embodiment, 12 solar cells10disposed at equal intervals in the row direction (the X axis direction) are connected by tab lines20to form one string10S. More specifically, each string10S is constituted by sequentially connecting pairs of solar cells10adjacent in the row direction (the X axis direction) using three tab lines20for each pair, so that all solar cells10in a line aligned in the row direction are connected.

A plurality of strings10S are formed. Strings10S are arranged in the other of the row direction or the column direction in which solar cells10are aligned. Six strings10S are formed in the present embodiment. As illustrated inFIG. 1, six strings10S are disposed at equal intervals along the column direction (the Y axis direction), parallel to one another.

Note that leading solar cell10in each string10S is connected to a connecting line (not illustrated) via tab lines20. Furthermore, solar cell10at the tail end in each string10S is connected to a connecting line (not illustrated) via tab lines20. Accordingly, a plurality of strings10S (six strings10S inFIG. 1) are connected in series or parallel to one another to constitute a cell array. In the present embodiment, two adjacent strings10S are connected in series to constitute a series connection (a series connection of 24 solar cells10), and three such series connections are connected in parallel.

As illustrated inFIGS. 1 and 4, solar cells10are disposed such that solar cells adjacent in the row direction and the column direction have a space therebetween. As described below, light reflectors30are disposed in the space.

In the present embodiment, solar cell10has a substantially quadrilateral shape in a plan view. Specifically, solar cell10is a 125-mm square having chamfered corners. Thus, one string10S is constituted such that sides of two adjacent solar cells10are facing each other. Note that the shape of solar cell10is not limited to a substantially quadrilateral shape.

The basic structure of solar cell10is a semiconductor pin junction, and as an example, solar cell10is constituted by an n-type monocrystalline silicon substrate which is an n-type semiconductor substrate, and an i-type amorphous silicon layer, an n-type amorphous silicon layer, and an n-side surface electrode which are sequentially formed on a principal surface side (front surface side) of the n-type monocrystalline silicon substrate, and an i-type amorphous silicon layer, a p-type amorphous silicon layer, and a p-side surface electrode which are sequentially formed on the other principal surface side (back surface side) of the n-type monocrystalline silicon substrate. The n-side surface electrode and the p-side surface electrode are transparent electrodes such as, for example, indium tin oxide (ITO) electrodes.

As illustrated inFIG. 3, front side collector electrode11(n-side collector electrode) electrically connected with the n-side surface electrode of solar cell10, and back side collector electrode12(p-side collector electrode) electrically connected with the p-side surface electrode of solar cell10are formed on solar cell10. Front side collector electrode11is formed in contact with, for example, the n-side surface electrode, and back side collector electrode12is formed in contact with, for example, the p-side surface electrode.

Front side collector electrode11and back side collector electrode12are each constituted by, for example, a plurality of finger electrodes formed linearly and orthogonally to the direction in which tab lines20extend, and a plurality of bus bar electrodes connected with the finger electrodes and formed linearly in the direction orthogonal to the finger electrodes (the direction in which tab lines20extend). The number of bus bar electrodes is the same as, for example, the number of tab lines20, and is three in the present embodiment. Note that front side collector electrode11and back side collector electrode12have the same shape, but may have other shapes.

Front side collector electrode11and back side collector electrode12are made of a conductive material having low resistance, such as silver (Ag). For example, front side collector electrode11and back side collector electrode12can be formed by screen printing a conductive paste obtained by dispersing conductive filler such as silver in a binder resin, in a predetermined pattern on the n-side surface electrode and the p-side surface electrode.

In solar cell10having such a configuration, both the front surface (n-side surface) and the back surface (p-side surface) serve as light-receiving surfaces. For example, light can enter through both front surface shield40and back surface shield50by using light-transmitting members for both front surface shield40and back surface shield50. The charge carriers generated in the photoelectric converter of solar cell10by the cell being irradiated with light are diffused to the n-side surface electrode and the p-side surface electrode as photoelectric currents, collected by front side collector electrode11and back side collector electrode12, and flow to tab lines20. The charge carriers generated in solar cell10can be efficiently taken out to an external circuit by providing front side collector electrode11and back side collector electrode12as described above.

As illustrated inFIGS. 1 and 2A, tab lines20(interconnectors) electrically connect pairs of adjacent solar cells10in string10S. As illustrated inFIG. 4, in the present embodiment, each pair of adjacent solar cells10are connected by three tab lines20disposed substantially parallel to each other. Tab lines20extend in the alignment direction of the pair of solar cells10to be connected.

Tab lines20are conductive elongated lines, and are ribbon-shaped metallic foil, for example. Tab lines20can be produced by cutting, for example, metallic foil, such as copper foil or silver foil having surfaces entirely covered with solder, silver, or the like into strips having a predetermined length.

As illustrated inFIG. 3, an end portion of each tab line20is disposed on the front surface of one solar cell10among two adjacent solar cells10, and another end portion of tab line20is disposed on the back surface of other solar cell10among two adjacent solar cells10.

Each tab line20electrically connects the n-side collector electrode (collector electrode on the front surface side) of one of two adjacent solar cells10, and the p-side collector electrode (collector electrode on the back surface side) of the other of two adjacent solar cells10. Specifically, tab lines20are connected with the bus bar electrodes of front side collector electrode11of one solar cell10and the bus bar electrodes of back side collector electrode12of other solar cell10. Tab lines20and front side collector electrode11(back side collector electrode12) are bonded together by, for example, thermo compression bonding with conductive adhesive21therebetween.

For example, a conductive adhesive paste, a conductive adhesive film, or an anisotropically conductive film (ACF) can be used as conductive adhesive21. A conductive adhesive paste is a pasty adhesive obtained by dispersing conductive particles in a thermosetting adhesive resin material such as an epoxy resin, an acrylic resin, or a urethane resin, for example. A conductive adhesive film and an anisotropically conductive film are obtained by dispersing conductive particles in a thermosetting adhesive resin material and forming the material into films.

Note that tab lines20and front side collector electrode11(back side collector electrode12) may be joined using solder material, rather than conductive adhesive21. A resin adhesive which does not contain conductive particles may be used, instead of conductive adhesive21. In this case, by appropriately designing the thickness of an applied resin adhesive, a resin adhesive softens when pressure is applied for thermo compression bonding, and consequently the surface of front side collector electrode11and tab lines20are brought into direct contact and electrically connected.

The surfaces of tab lines20in the present embodiment have recesses and protrusions20aas illustrated inFIG. 5A. When light which has entered solar cell module1falls on the surface of tab line20, recesses and protrusions20ascatter the light and cause the light to be reflected by the interface between front surface shield40and the air layer or the interface between front surface shield40and filling member60so that the reflected light is led to solar cell10. Accordingly, the light reflected by the surface of tab line20also effectively contributes to power generation, and thus the efficiency of power generation of solar cell module1improves.

A line obtained by forming a silver vapor-deposited film on the surface of copper foil having recesses and protrusions20aas the surface shape can be used as tab line20as described above. Note that the surface of tab line20may not have recesses and protrusions, but may rather be flat. A light reflector whose surface has recesses and protrusions may be separately stacked on a tab line having a flat surface.

As illustrated inFIGS. 1 and 2B, one or more light reflectors30are disposed on solar cell10. In the present embodiment, light reflectors30are disposed on solar cells10. Specifically, as illustrated inFIG. 4, light reflectors30are disposed on first solar cell10A and second solar cell10B disposed with a space therebetween.

As illustrated inFIG. 4, light reflectors30are disposed in the space between two adjacent solar cells10(first solar cell10A and second solar cell10B). In the present embodiment, light reflectors30are disposed on two solar cells10, overlapping the space between two adjacent solar cells10. Specifically, as light reflectors30, solar cell module1includes first light reflector30A disposed on an edge portion of first solar cell10A and overlapping the space between two adjacent solar cells10, and second light reflector30B disposed on an edge portion of second solar cell10B and overlapping the space.

Specifically, light reflectors30(first light reflector30A and second light reflector30B) are disposed on edge portions of solar cells10so as to be partially overlapping the space between two adjacent strings10S. In two adjacent strings10S, first light reflector30A disposed on first solar cell10A in one string10S and second light reflector30B disposed on solar cell10B in another string10S face each other. Stated differently, first light reflector30A extends toward second light reflector30B, and second light reflector30B extends toward first light reflector30A.

In the present embodiment, two light reflectors30are disposed on each solar cell10, except for solar cells10in outermost strings10S. Light reflector30has a tape-like shape that extends along the length of string10S (in the direction orthogonal to the alignment direction of first solar cell10A and second solar cell10B), an example of which is an elongated quadrilateral shape. Light reflector30is bonded to solar cell10along one side of solar cell10such that a lengthwise edge portion of light reflector30and an edge portion of solar cell10overlap. In a perimeter portion of solar cell10, a power generation ineffectual region is present in which charge carriers cannot be efficiently generated even if light enters, due to manufacturing reasons. Light reflector30may be bonded onto the power generation ineffectual region of solar cell10.

As illustrated inFIG. 4, in a plan view, two facing light reflectors30(first light reflector30A and second light reflector30B) disposed on two adjacent solar cells10(first solar cell10A and second solar cell10B) cover the space between two adjacent strings10S. Specifically, in a plan view, the space between two adjacent strings10S is covered with first light reflector30A and second light reflector30B facing each other.

In the present embodiment, as illustrated inFIG. 5B, two facing light reflectors30(first light reflector30A and second light reflector30B) are disposed such that the lateral surfaces along the edges of light reflectors30are in contact, fully covering the space but not overlapping each other. Yet light reflectors30may be disposed in a different manner. For example, as illustrated inFIG. 6A, two light reflectors30(first light reflector30A and second light reflector30B) may partially overlap each other. Stated differently, edge portions of two facing light reflectors30extending from the solar cells may overlap in the Z axis direction. Alternatively, as illustrated inFIG. 6B, two facing light reflectors30(first light reflector30A and second light reflector30B) may have a space therebetween, and the space between two adjacent strings10S may not be covered completely.

Note that two light reflectors30(first light reflector30A and second light reflector30B) disposed on two adjacent solar cells10(first solar cell10A and second solar cell10B) have the same shape. In the present embodiment, all light reflectors30included in solar cell module1have the same shape.

As illustrated inFIG. 5B, light reflectors30each include resin base31and reflective film32on the surface of resin base31. Resin base31includes polyethylene terephthalate (PET) or acrylics, for example. Reflective film32is a film made of metal such as, for example, aluminum or silver, and is an aluminum evaporated film in the present embodiment.

Here, recesses and protrusions31aare formed in the surface of resin base31, and reflective film32is formed on the surface of recesses and protrusions31aof resin base31by vapor deposition. In this manner, resin base31and reflective film32are laminated, thus forming light reflector30whose surface has recesses and protrusions. When light which has entered solar cell module1falls on the surface of light reflector30, recesses and protrusions31ascatter the light and cause the scattered light to be reflected by the interface between front surface shield40and an air layer or the interface between front surface shield40and filling member60so as to lead the reflected light to solar cell10. This also allows light that falls on a region which is located in the space between two adjacent solar cells10and is an ineffectual region (which is in the space between two adjacent strings10S, and cannot cause incident light to contribute to power generation in the present embodiment) to contribute to power generation effectively, whereby efficiency of power generation of solar cell module1improves.

As described above, light reflector30has an elongated quadrilateral shape whose length is 100 mm to 130 mm, width is 1 mm to 20 mm, and thickness is 0.05 mm to 0.5 mm, for example. In the present embodiment, light reflector30has a length of 125 mm, a width of 5 mm, and a thickness of 0.1 mm.

The thickness of resin base31is 50 μm to 500 μm, for example. With regard to recesses and protrusions31a, for example, a height between the peak and the bottom is at least 5 μm and at most 100 μm, and the spacing (intervals) between adjacent protruding portions is at least 20 μm and at most 400 μm. In the present embodiment, a height between the peak and the bottom is 12 μm, and the spacing (intervals) between adjacent protruding portions is 40 μm.

Note that in the present embodiment, recesses and protrusions31aare achieved by triangular grooves that extend along the lengths of light reflectors30, but the shapes are not limited to triangular grooves. Recesses and protrusions31amay be achieved by cones, quadrangular pyramids, polygonal pyramids, or combinations of such shapes, as long as recesses and protrusions31ascatter light.

Light reflector30is disposed on solar cell10using resin adhesive33that bonds the back surface of resin base31to solar cell10. For example, light reflector30and solar cell10are thermo-compression bonded with resin adhesive33therebetween so as to be bonded together. Resin adhesive33is, for example, ethylene-vinyl acetate (EVA), and may be disposed on the back surface of resin base31in advance. Thus, light reflector30may be achieved by resin base31, reflective film32, and resin adhesive33.

Front surface shield40(first shield) is a member which protects the front surface of solar cell module1, and protects the inside of solar cell module1(such as solar cell10) from the outside environment such as rainstorm and an external shock. As illustrated inFIGS. 2A and 2B, front surface shield40is disposed on the front surface side (n side) of solar cell10, and protects the light-receiving surface on the front side of solar cell10.

Front surface shield40is disposed on the light-receiving surface side of solar cell10, and thus is achieved by a light-transmitting member which transmits light in a wavelength range used for photoelectric conversion in solar cell10. Front surface shield40is, for example, a glass substrate (clear glass substrate) made of clear glass material or a resin substrate made of a hard resin material having a film-like or plate-like shape and light-transmitting and waterproof properties.

On the other hand, back surface shield50(second shield) is a member which protects the back surface of solar cell module1, and protects the inside of solar cell module1from the outside environment. As illustrated inFIGS. 2A and 2B, back surface shield50is disposed on the back surface side (p side) of solar cell10.

In the present embodiment, the back surface of solar cell10also serves as a light-receiving surface. Thus, back surface shield50protects the light-receiving surface on the back side of solar cell10, and is achieved by a light-transmitting member. Back surface shield50is a film-like or plate-like resin sheet made of a resin material such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), for example. Note that a glass sheet or glass substrate made of a glass material may be used as back surface shield50.

Note that when no light enters from the back surface side of solar cell10, back surface shield50may be a non-light-transmitting board or film. In this case, a non-light-transmitting member (light blocking member) such as, for example, a black member or a laminated film such as a resin film which includes metallic foil such as aluminum foil may be used as back surface shield50.

The space between front surface shield40and back surface shields50is filled with filling member60. Front surface shield40and back surface shield50are bonded and fixed to solar cell10by filling member60.

Filling member (filler)60is located between front surface shield40and back surface shield50. In the present embodiment, filling member60fills up the space between front surface shield40and back surface shield50.

Filling member60is made of a light-transmitting resin material such as ethylene vinyl acetate (EVA). Filling member60includes a front-surface side filling member and a back-surface side filling member between which solar cells10are sandwiched. For example, filling member60includes two resin sheets (EVA sheets) between which six strings10S are sandwiched and which are subjected to lamination processing (laminated).

Frame70is an outer frame which covers the perimeter edge portions of solar cell module1. Frame70in the present embodiment is an aluminum frame. As illustrated inFIG. 1, frame70includes four portions fitted on the four sides of solar cell module1. Frame70is bonded to the sides of solar cell module1with an adhesive, for example.

Note that solar cell module1includes a terminal box for taking out power generated by solar cells10, which is not illustrated. The terminal box is fixed to back surface shield50, for example. The terminal box includes a plurality of circuit components mounted on a circuit board.

Advantageous Effects and Others

The following describes advantageous effects of solar cell module1according to the present embodiment, also mentioning the circumstances which have led to the present disclosure.

Light which has fallen on the space between two adjacent solar cells had not contributed to power generation. Stated differently, the space between two adjacent solar cells was an ineffectual region which does not contribute to power generation.

In view of this, the inventors of the present application have conceived of disposing a light reflector in the space between two adjacent solar cells, and reflecting light which falls on this space using the light reflector so as to lead the incident light to a solar cell, thus causing the light which falls on the space to contribute to power generation. The inventors have conceived of, for example, bonding a light reflector such that the light reflector extends across a space between two adjacent solar cells.

However, when a plurality of solar cells are connected by tab lines into a string, the straightness of the string may be deviated by about several millimeters. In other words, the inventors found that the width of the space between two adjacent strings was partially different.

This is assumed to be influenced by manufacturing variations in the process of connecting a plurality of solar cells by tab lines to form a string (string formation process). For example, such variations are conceivably caused when disposing solar cells. Furthermore, distortion of the shape of a tab line also conceivably gives an influence. Specifically, tab lines are produced by pulling out narrow metallic foil wound around a bobbin and cutting the foil into strips. The wound foil consequently has a persistent winding shape, which results in distorted shapes of the tab lines.

As a result, the straightness of a string may be deviated in the string formation process, and the width of the space between two adjacent strings may be partially different.

In particular, if a string is formed using tab lines having a persistent winding shape, the string will be warped and curved gently in a plan view. In this case, as illustrated inFIG. 7, if two curved strings10S are disposed such that the curves are in opposite orientations in order to connect strings10S in series, the width of the space between two strings10S is greater in the central portion and smaller in both of the end portions.

For example, a variation in locations of solar cells10in the string formation process is about 1.5 mm. In addition, the amount of curvature of one string10S (deviation from a reference straight line in an end portion of the string) may be about 2 mm.

As described above, with regard to solar cells10of the solar cell module, the width of the space between two adjacent solar cells10(first solar cell10A and second solar cell10B) may be partially different. In particular, the width of the space between two adjacent strings10S may be partially different, and may be about 5 mm at the maximum.

In this case, if quadrilateral light reflectors are used for the space between two adjacent strings10S such that a single light reflector is disposed across each pair of adjacent solar cells10, a problem occurs that the light reflector cannot be appropriately disposed in the space between two adjacent solar cells10.

For example, if there is a portion (the central portion inFIG. 7) where the width of the space between two strings10S is greater than the length (width) of a light reflector in the transverse direction, the space between two strings10S in such a portion cannot be covered with the light reflector. In addition, if there is a portion (both of the end portions inFIG. 7) where the width of the space between two strings10S is smaller than the length (width) of a light reflector in the transverse direction, there is a possibility that the light reflector may cover the effectual region (power generating region) of solar cell10.

In view of this, the inventors of the present application have come up with an idea of, when disposing light reflectors in the space between pairs of adjacent solar cells10, disposing a light reflector on each of two adjacent solar cells10for the space between two adjacent solar cells10, rather than bonding a single light reflector across two adjacent solar cells10. In other words, the inventors have come up with an idea of disposing two light reflectors for the space between each pair of adjacent solar cells10.

Specifically, as illustrated inFIGS. 4 and 5B, first light reflector30A is disposed on an edge portion of first solar cell10A and overlaps the space between first solar cell10A and second solar cell10B adjacent to each other, and second light reflector30B is disposed on an edge portion of second solar cell10B and overlaps the space.

Accordingly, even if the width of the space between two adjacent strings10S is partially different, first light reflector30A and second light reflector30B can be disposed appropriately for the space between two adjacent solar cells10. Specifically, first light reflector30A and second light reflector30B can cover the space between two adjacent solar cells10as much as possible, even if the width of the space is great or narrow.

Specifically, first light reflector30A and second light reflector30B can cover the space between two adjacent solar cells10as much as possible when the width of the space is great, as illustrated inFIGS. 5B and 6B. Accordingly, for example, if the straightness of string10S deviates and thus the width of the space between two strings10S is partially great (central portion inFIG. 7), first light reflector30A and second light reflector30B can cover such a space as much as possible.

On the other hand, at a portion where the width of the space between two adjacent solar cells10is narrow, first light reflector30A and second light reflector30B can completely cover such a space between two solar cells10, as illustrated inFIGS. 5B and 6A. Accordingly, for example, when the straightness of string10S deviates, even if the width of the space between two adjacent strings10S is partially narrow (both of the end portions inFIG. 7), first light reflector30A and second light reflector30B can completely cover such a space.

As described above, in the present embodiment, two light reflectors30overlap the space between two adjacent solar cells10so as to eliminate the effects of variations in width of the space between adjacent strings10S.

As described above, in solar cell module1according to the present embodiment, first light reflector30A and second light reflector30B are disposed, overlapping the space between first solar cell10A and second solar cell10B adjacent to each other. Accordingly, the space between first solar cell10A and second solar cell10B adjacent to each other can be covered as much as possible so as to eliminate the space. Specifically, first light reflector30A and second light reflector30B can be disposed appropriately for the space between first solar cell10A and second solar cell10B adjacent to each other.

Accordingly, first light reflector30A and second light reflector30B can reflect, as much as possible, light which has fallen on the space (ineffectual region) between first solar cell10A and second solar cell10B adjacent to each other so as to lead the reflected light to solar cells10, whereby the efficiency of power generation of solar cell module1can be improved effectively.

For example, when light reflectors30are not disposed for the space between first solar cell10A and second solar cell10B adjacent to each other, light which has fallen on the space (ineffectual region) is reflected by the filling member on the back surface side (whose light utilization is about 40%), and enters solar cell module10. In contrast, when light reflectors30are disposed for the space between first solar cell10A and second solar cell10B adjacent to each other, light reflector30has light utilization of about 80%, and thus light utilization is about double the light utilization when light reflectors30are not disposed, whereby the efficiency of power generation of solar cell module1can be improved effectively.

Furthermore, in the present embodiment, light reflectors30are disposed on edge portions of solar cells10, rather than, for example, on back surface shield50. Stated differently, first light reflector30A is disposed on an edge portion of first solar cell10A, and second light reflector30B is disposed on an edge portion of second solar cell10B.

As described above, disposing light reflectors30on power generation ineffectual regions in edge portions of solar cells10improves productivity, and also efficiently utilizes the capacity of solar cells10to generate power.

In the present embodiment, first light reflector30A extends toward second light reflector30B, and second light reflector30B extends toward first light reflector30A.

Accordingly, first light reflector30A and second light reflector30B face each other, and thus readily cover the space between first solar cell10A and second solar cell10B adjacent to each other.

In the present embodiment, the space between two adjacent solar cells10(first solar cell10A and second solar cell10B) is included in the space between two adjacent strings10S, and light reflectors30are disposed, overlapping this space.

Accordingly, even if the straightness of string10S deviates and the width of the space between two strings10S is partially different, the space between two strings10S can be readily covered along the entire lengths of strings10S, by disposing light reflectors30on solar cells10. Specifically, the effects of variations in width of the space between two strings10S can be eliminated by pairs of light reflectors30which overlap the space.

The space between two adjacent strings10S may be partially wide. In this case, the space between first solar cell10A and second solar cell10B may not be completely covered with two light reflectors30, as illustrated inFIG. 6B.

In this case, the width of the space between solar cell10(first solar cell10A) in one of two adjacent strings10S and solar cell10(second solar cell10B) in the other of two adjacent strings10S, and the lengths of light reflectors30in the alignment direction of first solar cell10A and second solar cell10B may be determined to satisfy certain conditions.

Specifically, as illustrated inFIG. 5B, light reflectors30may be achieved such that a relation of W1+W2≥Gmax+C1+C2is satisfied, where W1denotes a width of first light reflector30A in an alignment direction (Y axis direction) of first solar cell10A and second solar cell10B, W2denotes a width of second light reflector30B in the alignment direction, C1denotes a width in the alignment direction of the edge portion of first solar cell10A on which first light reflector30A is disposed (a portion where first light reflector30A is bonded to first solar cell10A), C2denotes a width in the alignment direction of the edge portion of second solar cell10B on which second light reflector30B is disposed (a portion where second light reflector30B is bonded to second solar cell10B), and Gmax denotes a maximum width of the space between two adjacent strings10S.

Accordingly, even if the width of the space between two adjacent strings10S varies, the space between two adjacent strings10S can be completely covered with pairs of light reflectors30along the entire lengths of strings10S.

If the width of light reflector30in the alignment direction of first solar cell10A and second solar cell10B (in other words, the width in the direction in which light reflector30is projecting out) is excessively wide relative to the width of the space between two adjacent strings10S (space between first solar cell10A and second solar cell10B adjacent to each other), one of two light reflectors30facing each other may ride on solar cell10on which the other of two light reflectors30is disposed. For example, as illustrated inFIG. 8, first light reflector30A may ride on second solar cell10B, or second light reflector30B may ride on first solar cell10A. In this case, light reflector30covers the power generating region (effectual region) of solar cell10, which rather decreases efficiency of power generation.

In view of this, light reflection members30may be achieved such that W1, W2, C1and C2inFIG. 5Band Gmin satisfy a relation of W1≤Gmin+C1and W2≤Gmin+C2, where Gmin denotes a minimum width of the space between two adjacent strings10S (the space between the first string and the second string).

Accordingly, even if the space between two adjacent strings10S is partially narrow, a state as illustrated inFIG. 8, or specifically, a state in which one of two light reflectors30facing each other rides on solar cell10on which the other of two light reflectors30is disposed can be avoided. Thus, efficiency of power generation can be much more effectively improved using light reflectors30.

In the present embodiment, light reflector30having a tape-like shape that extends along the length of string10S is bonded to an edge portion of solar cell10such that a lengthwise edge portion of light reflector30overlaps the edge portion of solar cell10. Specifically, a lengthwise edge portion of first light reflector30A is bonded to first solar cell10A, and a lengthwise edge portion of second light reflector30B is bonded to second solar cell10B.

Accordingly, light reflector30can be disposed along the length of string10S in the space (ineffectual region) between two adjacent strings10S. Accordingly, the space between two adjacent strings10S can be covered in a wide range, and thus light which falls on this space can be reflected by light reflector30, and led to solar cell10. As a result, efficiency of power generation of solar cell module1can be further improved.

In the present embodiment, string10S is constituted such that sides of substantially quadrilateral solar cells are facing, and light reflectors30are bonded on sides other than the facing sides of two adjacent solar cells10in string10S. Specifically, light reflector30is bonded on a side of solar cell10which defines the space between two adjacent strings10S.

Accordingly, the space can be covered with light reflectors30while the space between two adjacent strings10S is reduced and the ineffectual region is decreased. Therefore, the efficiency of power generation as the entire solar cell module can be improved.

Variations and Others

The above completes description of solar cell module1according to the present disclosure based on the embodiment, yet the present disclosure is not limited to the above embodiment.

For example, in the above embodiment, as illustrated inFIG. 5B, two light reflectors30(first light reflector30A and second light reflector30B) which are facing each other have the same length (width) in the alignment direction of first solar cell10A and second solar cell10B, yet the present disclosure is not limited to this. For example, as illustrated inFIG. 9A, the length (width) of first light reflector30A in the above alignment direction and the length (width) of second light reflector30B in the above alignment direction may be different. Note that inFIG. 9A, the width of second light reflector30B is greater than the width of first light reflector30A. Accordingly, as illustrated inFIG. 9B, even if the space between two adjacent strings10S (space between first solar cell10A and second solar cell10B) is partially narrow, one of two light reflectors30facing each other is prevented from riding on solar cell10on which the other of two light reflectors30is disposed. Therefore, the efficiency of power generation can be improved further effectively using light reflectors30.

In the above embodiment, the lateral surfaces along the edges of two light reflectors30facing each other are vertical profiles, yet the present disclosure is not limited to this. For example, the lateral surfaces along the edges of two light reflectors30facing each other may have inclined profiles. Specifically, as illustrated inFIG. 10A, the lateral surface along the edge of first light reflector30A on the second light reflector30B side and the lateral surface along the edge of second light reflector30B on the first light reflector30A side may have inclined profiles. In this case, as illustrated inFIG. 10A, in a plan view, the inclined surfaces of first light reflector30A and second light reflector30B may be facing each other such that the space between first light reflector30A and second light reflector30B cannot be viewed. Accordingly, even if first light reflector30A and second light reflector30B have a space therebetween, the space between first solar cell10A and second solar cell10B can be substantially completely eliminated, and thus the efficiency of power generation can be improved effectively.

In the above embodiment, light reflectors30are disposed on the front surface shield40side of solar cells10, yet the present disclosure is not limited to this. For example, as illustrated inFIG. 10B, light reflectors30may be disposed on the back surface shield50side of solar cells10. In other words, light reflectors30may be disposed on the surfaces opposite the light entering surfaces.

In the above embodiment, two light reflectors30are disposed on each solar cell10except for solar cells10in outermost string10S, yet the present disclosure is not limited to this. For example, two light reflectors30may be disposed on each of all solar cells10, or string10S not located outermost may include solar cell10on which no light reflectors30are disposed. The number of light reflectors30disposed on each solar cell10may be one or three or more, rather than two. For example, light reflectors30may be disposed on the four sides of solar cell10, or a plurality of light reflectors30may be disposed on each side.

In the above embodiment, light reflectors30are disposed in the space between two adjacent strings10S, yet the present disclosure is not limited to this. For example, light reflectors30may be disposed in the space between two solar cells10adjacent in string10S.

In the above embodiment, the semiconductor substrate of solar cell10is an n-type semiconductor substrate, but may be a p-type semiconductor substrate.

In the above embodiment, solar cell module1is a bifacial module which includes front surface shield40and back surface shield50both serving as light-receiving surfaces, yet the present disclosure is not limited to this. For example, solar cell module1may be a monofacial module which includes front surface shield40and back surface shield50only one of which (for example, front surface shield40) serves as a light-receiving surface. If solar cell module1is a monofacial module, the p-side surface electrode is not necessarily transparent, and may be a reflective metal electrode, for example.

In the above embodiment, a semi-conducting material of a photoelectric converter of solar cell10is silicon, yet the present disclosure is not limited to this. Gallium arsenide (GaAs) or indium phosphide (InP) may be used as the semi-conducting material of the photoelectric converter of solar cell10.

The present disclosure may also include embodiments as a result of various modifications that may be conceived by those skilled in the art, and embodiments obtained by combining elements and functions in the embodiments in any manner without departing from the spirit of the present disclosure.