JP2000196121A - Photovoltaic element module and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic element module which has high conversion efficiency and can be manufactured with high productivity at a low cost. SOLUTION: A photovoltaic element module is manufactured, in such a way that after a semiconductor layer 102 and a transparent electrode 105 are formed on a conductive support substrate 101 using the substrate 101 as a rear- surface electrode and the substrate 101, layer 102, and electrode 105 are divided into photovoltaic elements, the plural elements are fixed on a mounting substrate 104 and connected in series by connecting the extended sections of opaque electrodes 103 formed on the transparent electrodes 105 of the low potential-side elements to the conductive support substrates 101 of high potential-side elements between adjacent elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic element module with low power generation efficiency loss, excellent productivity and low production cost, and a method for producing the same.

[0002]

2. Description of the Related Art Photovoltaic power generation using solar cells is a power generation method that has a very small load on the global environment. Therefore, very high expectations are placed on solar cells from the viewpoint of environmental protection. However, at present, due to its high manufacturing cost, solar power generation is not economically viable compared to other thermal power generation, nuclear power generation, and the like. To overcome this situation, it is essential to reduce manufacturing costs.

[0003] Methods for reducing the manufacturing cost are classified into two types. One is to improve the conversion efficiency and reduce the area of the solar cell module, and to reduce the material cost by making the module structure simple and rational. Another is to reduce manufacturing equipment costs and labor costs by simplifying the manufacturing process and module structure and improving productivity.

[0004] Methods for improving the conversion efficiency are further classified into two. One is an invention that increases the conversion efficiency of a photovoltaic structure in a semiconductor, which can be said to be the basis of a solar cell element. In other words, the invention is to increase the amount of power generated by the element per unit area. The other is an invention of a module structure combining elements having a unit area. Generally, the electric conductivity of the surface of the semiconductor layer is low, and in order to extract large power, a module structure in which unit elements having a surface electrode structure, a photovoltaic structure, and a back electrode structure are serialized and combined is required. In this module structure, improving the effective utilization rate of the photovoltaic region, reducing the source of Joule loss of power, and increasing the area filling rate of the unit element on the module surface are the conversion efficiencies of the module (A.M1). It is an invention to increase the ratio of the incident light energy per module area to the module output under 0.5.

There have been many inventions for improving the conversion efficiency by improving the photovoltaic structure and the module structure, and improving the productivity by simplifying the module structure. The following are examples of conventional examples which are considered to be particularly effective among them.

A method for manufacturing a photovoltaic structure is disclosed in US Pat.
No. 69730. This example is a method for manufacturing a thin-film solar cell by vacuum film formation. A thin film solar cell formed by vacuum film formation is the most advantageous solar cell for cost reduction because it uses few materials and has excellent productivity. It is also expected to be short of silicon worldwide and is currently the most promising solar cell.

[0007] The vacuum film forming method is a method for forming a semiconductor layer on a supporting substrate in a vacuum chamber. In this method, the selection of the supporting substrate is important. When a rigid supporting substrate such as glass is used, film formation is performed for each substrate, and evacuation is performed every time, or a complicated substrate transport system in a vacuum is required, resulting in poor productivity. In addition, the module forming process after the film forming process is also a batch process, and the productivity is greatly reduced in the entire manufacturing process.

In the above conventional example, a flexible substrate is used as a support substrate. The flexible substrate can be compactly stored in a vacuum chamber as a roll by forming it into a belt shape and winding it around a core material. By forming a film on the substrate surface while unwinding the roll, and winding the film on another core material, a large area film can be formed without opening the chamber. Therefore, the production speed is very high, the film forming apparatus is simple, and the production cost is low. This method is called a roll-to-roll method.

The invention of the module structure is disclosed in
JP-A-21501 discloses that a photovoltaic layer formed by vacuum deposition on a conductive support substrate is divided for each substrate, and a front electrode is formed on the front surface to form a photovoltaic element (a back electrode, a semiconductor, A module structure in which one surface electrode of an adjacent photovoltaic element and the other conductive support substrate are electrically connected in series using a series member is disclosed. FIG. 3 schematically shows the configuration. In the figure, 3
01 is a conductive support substrate, 302 is a photovoltaic layer, 303 is a surface electrode, and 306 to 308 are series members. In this example, a flexible conductive substrate can be used. Therefore, since the photovoltaic layer can be formed by the above-described roll-to-roll method, it can be said that this is a module form which is extremely advantageous for cost reduction.

As another invention of a module structure in which the above-mentioned roll-to-roll method can be used, US Pat.
No. 97041 discloses an example in which photovoltaic elements are mounted on an insulating support substrate at high density. In this example, a back electrode of each element and an entire surface of a semiconductor layer and a transparent electrode are formed as a thin film on an insulating support substrate, and only the transparent electrode is scribed to be separated into element units. The serialization is performed by electrically connecting the front surface electrode formed on the transparent electrode and the other back surface electrode. FIG. 2 schematically shows the configuration. In the figure, 201 is a back electrode, 204 is an insulating support substrate, 202 is a semiconductor layer, 203 is a front electrode, 2
05 is a transparent electrode.

[0011]

The above-mentioned module form has the following problems to be solved.

In the module disclosed in Japanese Patent Application Laid-Open No. 6-21501, there is a problem that the filling rate of the photovoltaic elements in the module cannot be sufficiently increased and the conversion efficiency of the module is low.

In this embodiment, the elements that fix the elements are only the series members between the elements. Therefore, as a function of the series member between the elements, it is necessary to have a strength for mechanically holding the gap between the elements, in addition to the electrical connection holding property. For this reason, it is necessary to use a series member that is thicker and wider than the thickness and width required for electrical connection. On the other hand, in order to increase the filling rate of the photovoltaic element and increase the conversion efficiency of the module, it is required that the interval between the elements is as narrow as possible within a range where the insulation between the elements is maintained. There is a limit in accurately attaching a member that is thick and wide for maintaining strength and short in length for shortening the interval between the elements, so that the interval between the elements is long and the conversion efficiency is sufficient. It was difficult to raise.

The module disclosed in US Pat. No. 4,697,041 has the following problems.

(1) It is difficult to make the back electrode sufficiently thick, so that Joule loss increases and efficiency loss increases.

In this embodiment, only the back electrode must be separated without separating the support substrate itself. Generally, the separation groove is formed by a method such as laser scribe and etching, but the ease of processing greatly depends on the thickness of the back electrode. To facilitate the processing, the back electrode is formed as a thin film,
Although it must be made very thin, as a result, even when a metal having a low volume resistivity is used for the back electrode, it is difficult to sufficiently reduce the sheet resistivity, and the Joule loss in the back electrode is large.

(2) Since the number of photovoltaic layers not contributing to the power generation in the element isolation groove (the gap between the serialized element and the element) increases, the material cost increases and the module conversion efficiency decreases.

In this embodiment, the photovoltaic layer existing in the separation groove portion is removed at the time of forming the groove, or becomes an ineffective portion which does not contribute to power generation even if it is not removed. Therefore, the number of separation grooves must be small.

However, in this embodiment, many grooves for separating the elements are required. This is due to the high surface resistivity of the back electrode as described above. That is, in order to prevent an increase in Joule loss due to high resistance, it is indispensable to reduce the size of the element on the supporting substrate to reduce the current flowing through the back electrode, or to shorten the length of the back electrode. For that purpose, it is necessary to increase the number of separation grooves for separating the elements. The large number of separation grooves causes an increase in useless photovoltaic layers, an increase in material cost, and a decrease in module conversion efficiency.

(3) Since the number of separation grooves is large, the number of series per module increases. For this reason, the output voltage of the module has increased, and it has been difficult to take safety measures and insulation when installing the module on the roof.

(4) Fine processing must be performed with high precision over a large area, and productivity and yield are extremely deteriorated.

In this embodiment, the photovoltaic layer existing in the separation groove is removed when the separation groove is formed, or becomes an ineffective portion that does not contribute to power generation even if it is not removed. Therefore, in order to reduce the ineffective portion, the width of the separation groove must be very narrow. The separation groove between adjacent elements is a space that forms an electrical connection between the front electrode of one element and the back electrode of the other element. Therefore, if this portion is narrow, the productivity and yield in the process of forming the electrical connection portion will be reduced.

(5) Since an insulating substrate is used as a supporting substrate for forming a photovoltaic layer, it is difficult to form a photovoltaic layer having high characteristics by a roll-to-roll method with high productivity.

In this embodiment, an insulating substrate or a substrate having an insulating surface must be used as a supporting substrate on which a film is formed. Therefore, the substrate is limited to a rigid ceramic substrate such as glass, a flexible substrate made of resin, and a metal substrate having an insulating coating. A rigid substrate is not suitable for the roll-to-roll method, and the productivity is reduced. The resin substrate has a poor function of retaining the shape of the element on the substrate due to its high elasticity. Further, impurities adsorbed on the surface during vacuum film formation on the substrate are mixed into the film formation layer, and the characteristics of the layer deteriorate. Since the melting point of the substrate is low and the substrate temperature at the time of film formation cannot be increased, there are weak points such as difficulty in obtaining a photovoltaic layer having sufficient characteristics. Since the metal substrate having the insulating coating forms the insulating layer, the manufacturing cost increases.

An object of the present invention is to solve the above problems and to provide a photovoltaic element module having high conversion efficiency and excellent productivity at low cost.

[0026]

Means for Solving the Problems The present inventors have conducted intensive research and development in order to solve the above-mentioned problems, and as a result, have found that the following photovoltaic element module is the best.

That is, in the photovoltaic element module of the present invention, a plurality of photovoltaic elements having at least a semiconductor layer and a surface electrode on a conductive support substrate as a back electrode are provided on the mounting substrate via a gap. , And has a serial structure in which an extension of one surface electrode of the adjacent photovoltaic elements is connected to the back electrode of the other photovoltaic element.

Further, it has been found that the following manufacturing method is the best in the method of manufacturing the photovoltaic element module.

That is, in the method of manufacturing a photovoltaic element module according to the present invention, a plurality of photovoltaic elements having at least a semiconductor layer and a surface electrode on a conductive support substrate as a back electrode are provided via a gap. A method for manufacturing a photovoltaic element module having a serial structure in which an extension of one surface electrode of photovoltaic elements adjacent to each other is fixedly mounted on a mounting substrate and connected to a back electrode of the other photovoltaic element. And at least a step of forming at least a semiconductor layer on the conductive support substrate, a step of dividing the conductive support substrate having at least the semiconductor layer, and a step of fixing the divided conductive support substrate on a mounting substrate And the following.

[0030]

The following functions operate on the photovoltaic element module of the present invention to solve the above-mentioned problems.

In the photovoltaic element module of the present invention, each photovoltaic element is fixed on a mounting substrate, and the mounting substrate has a function of maintaining a gap between the elements. Therefore, the function of maintaining the element gap is not required at the electrical connection between one surface electrode of the adjacent element and the other back electrode. Therefore, it is easy to reduce the distance between the elements by reducing the extension of the surface electrode, and it is possible to increase the module conversion efficiency.

In the photovoltaic element module of the present invention, since the back electrode is a conductive support substrate, the self-shape can be maintained and the shape of the photovoltaic layer can be maintained. Therefore, since it has a sufficient thickness, it is very easy to reduce its sheet resistivity. Therefore, the Joule loss in the back electrode decreases, and the conversion efficiency increases.

In the present invention, a conductive support substrate having at least a semiconductor layer as a photovoltaic layer formed on a surface thereof is divided. The plurality of cells thus obtained are arranged and fixed on the mounting board at appropriate intervals. Therefore, the photovoltaic layer does not originally exist in the isolation groove of the element of the obtained module, and a wasteful portion is omitted. Further, since the back surface electrode has a low sheet resistivity as described above, it is easy to sufficiently reduce the Joule loss in the back surface electrode even if the element size is increased. Therefore, the number of grooves for separating elements can be reduced, and the element filling rate in the module can be increased. As a result, module conversion efficiency increases.

In order to reduce the number of photovoltaic elements in series,
The output voltage of the module decreases, and insulation measures and safety measures during construction become easier.

In the present invention, as described above, since the divided cells are arranged and fixed on the mounting substrate, the width of the dividing groove between the elements is set within a range where the filling rate of the elements is not reduced, and the module conversion efficiency is significantly reduced. It can be set freely within a range not to be set. Therefore, it is possible to sufficiently secure a space for forming an electrical connection portion between one surface electrode and the other back electrode of the adjacent photovoltaic element, thereby preventing productivity and yield from being deteriorated. Easy.

Further, in the present invention, the following functions and effects can be obtained by specifying each member.

When the conductive support substrate is made of a metal, the effect of reducing Joule loss appears remarkably. Metal has the highest conductivity as a back electrode and has a high effect of preventing Joule loss. Further, it has sufficient strength and melting point as a support substrate at the time of film formation. Further, the material has good surface cleaning properties, and can be said to be a material suitable for use as a substrate in vacuum film formation.

When the conductive support substrate is a foil material, it has flexibility and is suitable for the roll-to-roll method, so that module productivity is improved. In the present invention, it is essential to divide the substrate into element sizes, but when the supporting substrate is a foil material, it is very thin compared to a plate material because it is thin enough to have flexibility. Easy and more productive.

When the semiconductor layer is formed on one entire surface of the conductive support substrate, it is possible to increase the ratio of the effective power generation region in the module, and the conversion efficiency of the module increases.

When the conductive support substrate is larger in size than the semiconductor layer and has a portion protruding from the semiconductor layer,
The area of the semiconductor layer (photovoltaic unit) with respect to the module area decreases. This is because, even if elements in which the conductive support substrate protrudes from the semiconductor layer are arranged as densely as possible on the mounting substrate, the protruding portion becomes an obstacle, and the semiconductor layers, which are effective power generation areas, may be densely arranged. It is impossible.
This means that the effective power generation area in the module is reduced, which hinders an improvement in conversion efficiency. However, this does not apply to an element having a support substrate that does not protrude from the semiconductor layer.

When the extension of the surface electrode is connected to the end face of the conductive support substrate of the adjacent element, the utilization rate of the photovoltaic layer is increased, and as a result, the module efficiency is improved. Also, productivity is improved.

One problem common to the embodiments disclosed in Japanese Patent Application Laid-Open No. Hei 6-21501 and US Pat. No. 4,694,041 is that an electric connection portion that connects to one surface electrode of an adjacent photovoltaic element is connected to the other. There is a problem that the element is connected to the main plane of the back electrode of the element and reduces the effective power generation area or significantly lowers productivity.

In the case of the module disclosed in Japanese Patent Application Laid-Open No. 6-21501, a series member of photovoltaic elements is connected to the main plane of one surface electrode and the other back electrode of an adjacent element (FIG. 3). This is because the series member must have mechanical strength for maintaining the element gap, and it is not sufficient to simply connect the series member, which is an extension of the front electrode, to the back electrode end face. . In particular, when connecting to the main plane on the light incident side, the photovoltaic layer (semiconductor layer) formed on the connection main plane is removed, and a series member is connected to that portion. Therefore, the utilization rate of the photovoltaic layer is reduced by the connection area, and the effective power generation area is reduced. Further, when connecting to the anti-light incident side, the work is performed from both sides of the element in the connection step, and the productivity is poor.

Also, in the case of a module having a back electrode formed in a thin film on an insulating support substrate, such as the module disclosed in US Pat. The extension of the front electrode is connected to the main plane of the other back electrode. This is because sufficient electrical continuity cannot be obtained even when connected to the end face because the thickness of the back electrode is extremely thin. in this case,
It is not possible to connect the extension to the back electrode main plane on the side in contact with the insulating support substrate because it is necessary to once peel off the interface between the insulating support substrate and the back electrode. Therefore, it is connected to the main plane on the side in contact with the photovoltaic layer (semiconductor layer) on the opposite side. At this time, the semiconductor layer existing on the portion connecting the extension on the main plane is removed, or the extension is connected to the main plane by penetrating the semiconductor layer. Therefore, in any case, the power generation area above the portion connecting the extension of the main plane is wasted.

However, in the case of the present invention, since the back electrode has a certain thickness as a conductive support substrate, its end face is large, and it is easy to connect an extension of the front electrode. By connecting to the end face, there is no power generation area wasted in connection.

In the present invention, since the photovoltaic element has a plurality of extensions of the surface electrode, the effective power generation area is further increased, and the conversion efficiency of the module is increased.

When the front electrode protrudes and extends from the edge of the semiconductor layer at one location and is connected to the back electrode of an adjacent element, an electric path for collecting the current flowing through the front electrode at that location. Is required in the surface electrode. Generally, the value of the current flowing through the current collecting electrical path is large, and the resistivity of the constituent material must be reduced in order to prevent Joule loss at that portion. Low resistivity materials are generally opaque, so the electrical paths cast shadows on the surface of the semiconductor layer, reducing the effective power generation area. However, the extension of the surface electrode protrudes from the end of the semiconductor layer from a plurality of places without collecting electricity at one place, and is electrically connected to the back surface electrode of an adjacent element to reduce the area of the above-described electric path. It has the effect of reducing and increasing the effective power generation area.

If the extension of the surface electrode is formed of a conductive resin, the present invention can be further easily implemented. That is, the surface electrode can be formed by printing using a conductive resin,
The formation process is very easy. Also, due to its plasticity, it can be easily installed in a narrow gap between elements. Therefore, the interval between the elements can be extremely narrowed, and this has the effect of increasing the conversion efficiency of the module.

When the extension of the surface electrode is a metal wire, the effect of the present invention becomes more remarkable. That is, factors that limit the element size include the resistivity of the front electrode layer in addition to the area resistivity of the back electrode. When a surface electrode having a low resistivity such as a metal wire is used, the element size can be further increased, the number of division grooves between the elements is reduced, and the module efficiency is further increased.

[0050]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional perspective view of one embodiment of the photovoltaic element module of the present invention. The element in FIG. 1 is a diagram schematically showing the configuration of the module of the embodiment. still,
The present invention is not limited to the configuration of FIG.

In FIG. 1, reference numeral 101 denotes an insulating support substrate as a back electrode, 102 denotes a semiconductor layer, 103 and 105 denote surface electrodes, 105 denotes a transparent electrode, and 103 denotes an opaque electrode. 106 is an extension of the surface electrode, and 107 is an insulator. Hereinafter, each member will be described.

(Insulating support substrate (back surface electrode): 101)
It is a conductor that guides current from the semiconductor layer 102 and is a support substrate that holds the shape of the semiconductor layer. Here, the supporting substrate is a plate-like member having a thickness capable of maintaining at least a self-shape and a thickness capable of withstanding a tension applied to the unit element.

A characteristic desired as a conductor in the conductive support substrate used in the present invention is that the sheet resistivity is low.

Further, the characteristics desired as the supporting substrate are to have appropriate rigidity for holding the semiconductor layer, to have a thermal expansion coefficient close to the thermal expansion coefficient of the semiconductor layer, and to be able to easily divide the substrate. When a vacuum deposited semiconductor layer is used, it has flexibility, a roll-to-roll method can be used, it has a high melting point higher than the temperature at the time of semiconductor layer formation, Is difficult to adsorb.

A metal foil is most desirable as having the above characteristics. Specific examples include aluminum, SUS, copper, nickel, molybdenum, a simple substance such as gold, and a foil material such as an alloy. In particular, aluminum, SUS, and copper have appropriate conductivity, flexibility, melting point, It has rigid elasticity and detergency and is preferably used.
The metal foil is also excellent in that it can be easily divided by a roll cutter, a laser cutter, or the like. Considering the above points, the most preferable thickness of the metal foil is 10 μm to 200 μm.
m. A metal layer of silver, aluminum, or the like may be formed on the surface of the conductive support substrate for reflecting light transmitted through the semiconductor layer. The surface may be textured to induce diffuse reflection.

When the conductive support substrate does not have a portion (a portion viewed from above) protruding from the end of the semiconductor layer when viewed from the light incident side, the cells are effectively filled in the module, and the power generation area is formed. Can be increased, which is preferable.

(Semiconductor layer: 102) The semiconductor layer is a layer in which carriers are excited by the incidence of light to generate a potential difference between the front and back surfaces of the layer. A stack of p-type, i-type, and n-type semiconductor layers, and a layered structure such as a double-structure or a triple-structure in which these are stacked can be preferably used.

The present invention is applicable and effective to a thick-film crystalline or polycrystalline semiconductor. However, it is particularly effective for thin film semiconductors. The reason is that a thin film can be easily divided after forming a semiconductor layer all over a large substrate. In addition, if it is a thin film as a whole, it is not affected by the atomic arrangement. Furthermore, a thin film single crystal, a thin film polycrystal, amorphous silicon, a thin film compound semiconductor, or a multilayer structure in which these are stacked may be used.

A pin type amorphous silicon (a-S
i) When forming a photovoltaic element, a-Si: H, a-Si: F, a-Si: H
Si: H: F, a-SiGe: H, a-SiGe: F,
a-SiGe: H: F, a-SiC: H, a-SiC:
So-called Group IV and I such as F, a-SiC: H: F
Group V alloy-based amorphous semiconductors and microcrystalline semiconductors are exemplified. The semiconductor material constituting the p-layer or the n-layer can be obtained by doping the above-mentioned semiconductor material constituting the i-layer with a valence electron controlling agent. As raw materials,
As a valence electron controlling agent for obtaining a p-type semiconductor, a compound containing an element of Group III of the periodic table is used. II
Examples of group I elements include B, Al, Ga, and In. As a valence electron controlling agent for obtaining an n-type semiconductor, a compound containing an element of Group V of the periodic table is used. Group V elements include P, N, As, and Sb.

As a method for forming the amorphous silicon semiconductor and the microcrystalline silicon semiconductor layer, there are a vapor deposition method, a sputtering method, an RF plasma CVD method, and a microwave plasma CVD method.
Method, VHFCVD method, ECR method, thermal CVD method, LPCV
A known method such as Method D is used as desired. As a method adopted industrially, an RF plasma CVD method in which a raw material gas is decomposed by RF plasma and deposited on a substrate is preferably used. Further, in the RF plasma CVD, there are problems that the decomposition efficiency of the source gas is as low as about 10% and the deposition rate is as low as about 1 ° / sec to 10 ° / sec. Attention has been paid to microwave plasma CVD and VHF plasma CVD. As a reaction apparatus for performing the above film formation, a known apparatus such as a batch type apparatus or a continuous film formation apparatus can be used as desired.

The semiconductor layer formed on the entire surface of at least one main plane of the conductive support substrate has an effect of increasing the ratio of the effective power generation area in the module,
preferable.

(Surface electrodes: 103 and 105) The front electrodes are electrodes for extracting current from the back electrode and the pair of semiconductor layers, and are electrodes formed on the light incident side.

In the present invention, the desired characteristics of the surface electrode are that light is not blocked as much as possible, that the transmittance of the transparent electrode is high, and that the shadow of the surface electrode formed on the semiconductor is as small as possible for the opaque electrode. The area is small and the sheet resistivity is low. Generally, light transmission and low sheet resistivity are conflicting requirements. Many electrodes have been devised which satisfy both requirements as much as possible, and are applicable to the present invention.

As the transparent surface electrode, SnO ₂ , In ₂
O ₃ , ZnO, CdO, CdSnO ₄ , ITO (In ₂ O ₃
+ SnO ₂ ) or a metal oxide formed by a sputtering method, a resin obtained by dispersing these oxides in a resin to form a paste, applying a sol-gel method, gold, indium, etc. It is possible to use a metal thin film formed of such a thickness as to have a light transmitting property.
Since the light transmittance of the transparent electrode is inversely proportional to the thickness of the electrode,
Generally, it is formed very thin on the entire surface of the element, but it is also possible to form it only on a necessary part. It is also possible to change the thickness according to the current density flowing through the electrodes. The transparent electrode has a wavelength of, for example, 4 nm in order to efficiently absorb light from the sun or a white fluorescent lamp into the semiconductor layer.
It is desirable that the light transmittance at 00 nm is 85% or more. Generally, it is difficult for a transparent electrode to sufficiently lower the sheet resistivity, and it is preferable to combine the transparent electrode with the next opaque electrode.

As the opaque electrode, a conductive resin paste in which conductive particles are dispersed in a paste resin and printed on the surface of the semiconductor layer by printing is rich in plasticity and easily formed in a gap such as an element gap. It is suitable. The printed electrode is suitable because it can be printed in any shape such as a comb shape or a grid shape. Further, the thickness and the width can be changed according to the current density. Silver, as conductive particles,
Fine particles of gold, copper, platinum, palladium, nickel and alloys thereof, fine particles of carbon, titanium oxide, and the like are generally used. As the paste resin, a thermosetting resin (epoxy resin, crosslinkable urethane resin or the like) or thermoplastic (silicone resin or the like) is appropriately selected. It is also preferable to mix a coupling agent to increase the adhesion to the semiconductor layer or mix an antioxidant to prevent oxidation of the metal particles. It is also effective to coat a low melting point alloy such as solder thereon to lower the resistivity.

An opaque electrode of a type in which a metal wire coated with a conductive resin is adhered to the semiconductor surface is also preferably used because the resistivity can be easily reduced. As the metal wire, an alloy such as copper, aluminum, gold, silver or SUS is used. Further, those having a plating coating on their surfaces are also used. As the conductive resin, one obtained by appropriately adjusting the viscosity, the degree of curing, and the like of the above-described conductive resin paste is used. It is desirable that the bonding pattern be optimized according to device characteristics such as parallel lines and grid shapes.

As another opaque electrode, an electrode obtained by forming a thin film of metal on the surface of a semiconductor layer can be used. Aluminum,
Silver, gold, palladium, nickel, solder, lead, tin and their alloys, which are formed on the semiconductor surface by masking in any desired shape by vapor deposition, sputtering, electrodeposition plating, etc., or comb-shaped after being formed on the entire surface What is etched in a lattice shape is effective.

The above-mentioned transparent electrode and opaque electrode are preferably used in an appropriate combination. FIG. 1 illustrates this case, wherein 103 is the above-described opaque comb-shaped electrode, and 105 is a transparent electrode.

When a thin-film semiconductor layer is used and the front electrode and the rear electrode are close to each other, and when the transparent electrode is formed over the entire surface of the semiconductor layer, the transparent electrode is slightly smaller than the surface of the semiconductor layer. After forming or forming the entire surface, it is effective to remove a small amount of the transparent electrode along the edge of the surface of the semiconductor layer in order to prevent a short circuit between the front electrode and the back electrode (see FIG. 1). A known method such as a mask method can be used in the case of forming a slightly smaller area, and a known method such as chemical etching or laser etching can be used in the case of removing an edge portion.

(Mounting board: 104) The mounting board is a board for fixing and serializing the divided cells, and any board having strength and insulating surface for maintaining the element gap can be used. Specific examples include a resin film sheet, glass, ceramic, and a metal plate whose surface is insulated. In order to maintain the element gap and prevent mechanical stress applied to the extension of the surface electrode existing between the elements, the smaller the thermal expansion coefficient, the better. It is also effective to have an appropriate rigidity. In particular, many resin film sheets have appropriate strength and insulating properties, and have a high adhesive strength to the metal back electrode, and are easily used for fixing the element. Among them, polyester resins and polyimide resins are excellent in insulation and strength. Polyimide-based resins are further excellent in small coefficient of thermal expansion.

(Extension of Front Electrode: 106) The extension of the front electrode is a path for electrically connecting one surface electrode and the other back electrode of the adjacent photovoltaic element. The required properties are high electric conductivity and easy to suppress Joule loss. It may be opaque because it exists in the element gap. Therefore, it is desirable to use a metal thin film, a metal strip, a metal wire, a metal filler made of a conductive resin or the like. The extension can be connected to the front and back electrodes by bonding or thermocompression bonding using a conductive adhesive.
Melt bonding and welding of low melting point metals are preferred. When bonding with a conductive adhesive, add a coupling agent to the adhesive to increase the adhesive strength with the back electrode, or add an antioxidant to prevent oxidation of the back electrode surface and increase in resistance Is valid. The welding is performed by a known method such as ultrasonic wave, resistance heating, and laser welding.

It is preferable that the opaque electrode formed as a part of the above-mentioned surface electrode and formed integrally with the same member is easy and easy to dispose (see FIG. 1). The connection between the back electrode and the extension of the front electrode is formed on an end surface (cut surface) other than the main plane of the back electrode, which is effective for expanding the photovoltaic area (see FIG. 1). Further, it is also effective to fill the gap between the elements with an extension of the surface electrode to reinforce the connection.

When the extension of the surface electrode is one place,
A current collecting path for collecting the current flowing through the surface electrode in one place is required on the semiconductor layer. It is preferable that the number of the current collecting paths be reduced because a shadow is formed on the semiconductor layer surface. Therefore, it is desirable to protrude from the end of the semiconductor layer at a plurality of locations.

In order to prevent the extension of the front electrode for electrically connecting adjacent elements from short-circuiting with the back electrode of the element on the low potential side, it is necessary to provide a sufficient space between the two. It is. Further, it is preferable to fill the space with an insulating material. As the insulating material, a resin is preferable because its installation and molding are easy. Further, a transparent material is desirable so as not to block light even if it is installed on the light incident side surface of the semiconductor layer.

(Step of Dividing Insulating Supporting Substrate (Back Electrode): 101) The insulating supporting substrate having at least a semiconductor layer formed on its surface is divided by die pressing, laser cutting, water jet, roll cutter, and disk cutter. And other known methods can be used. In particular, when the insulating support substrate is made of a metal foil and the semiconductor layer is a thin film semiconductor, a roll cutter or a laser cut is suitable.

(Step of Fixing Insulating Support Substrate (Back Electrode): 101 on Mounting Substrate: 104) In order to fix the insulating supporting substrate having at least a semiconductor layer, which is divided into element units, to the mounting substrate, The simplest and most preferable method is to sandwich and fix a resin as an adhesive between the mounting substrate and the insulating support substrate. In this case, as the resin, a general acrylic or silicone resin can be used by spray coating or roller coating. It is also possible to directly laminate the insulating support substrate using a resin film for the mounting substrate. In this case, the resin material is preferably a thermoplastic resin. This is because the thermoplastic resin can be easily pressed by adding a heating step. Particularly, a polyester resin and a polyimide resin are effective.

The step of forming the surface electrode and the extension of the surface electrode is not particularly limited. Even if the entire surface electrode is formed after the division step, the transparent electrode may be formed on an insulating support substrate. The opaque electrode and the extension may be formed after forming and dividing and fixing on a mounting substrate.

[0079]

EXAMPLES Hereinafter, specific examples of the structure of the photovoltaic element module of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 A photovoltaic element module having a structure schematically shown in FIG. 1 was manufactured by the following steps.

As the insulating support substrate 101, an aluminum foil (thickness 15 μm, width 30 cm) was used. The aluminum foil wound around a metal bobbin in a roll of 1000 m is put into a vacuum chamber, and while the aluminum foil is wound around another metal bobbin in the vacuum chamber, a light reflecting layer is formed on the surface of the aluminum foil in the middle chamber. (Not shown), a semiconductor layer 102 was formed. The light reflecting layer is made of ZnO by sputtering.
Was deposited at 1 μm, and two layers of a combination of a p layer, an i layer, and an n layer were formed as the semiconductor layer 102 by a CVD method. Z
A texture structure was formed on the nO surface to increase the light reflectance. The thickness of the semiconductor layer was 500 °. Further, similarly, a transparent electrode 105 which is a part of the surface electrode was formed on the semiconductor layer by a roll-to-roll method and a sputtering method. The material of the transparent electrode is ITO and the thickness is 700 °.

Next, the insulating support substrate having the semiconductor layer and the transparent electrode formed thereon is rolled to a length of 2 to 20 cm using a roll cutter.
Each cell was cut. The cutting was performed by repeating a series of operations of unwinding a fixed amount of the substrate from the roll onto the resin table and cutting while pressing the roll cutter.

Next, as the mounting substrate 104, the width 40c
m, a length of 1 m and a thickness of 100 μm were separately prepared on a polyimide substrate, and the cut cell was 0.5 mm on the substrate surface.
They were lined up with bonding at intervals. Adhesion was performed by spraying a chloroprene-based synthetic rubber adhesive. Cell length 2c
Dozens of different types from m to 20 cm were manufactured.

Next, the edge of the transparent electrode was removed by 0.2 mm in width along the edge of the cell. This is to prevent a short circuit between the transparent electrode and the insulating support substrate at the end of the element.

Further, an insulative transparent resin was printed as an insulator 107 on one end of the element adjacent to the cell, which was brought to the lower potential side by serialization, by a known screen printing method. this is,
This is to prevent the opaque electrode 103 which is a part of the surface electrode and the conductive support substrate from being short-circuited in the same element. As shown in FIG. 10, the screen pattern used was a pattern in which strips having the same length as the cell width and 1 mm width were arranged at cell length intervals. In the figure, reference numeral 1001 denotes a pattern of the insulator 107. The alignment between the screen and the insulating support substrate was performed by aligning the edge of the substrate with the position reference mark of the screen. All cells were printed at once for each module. As the insulating transparent resin, a thermosetting epoxy resin was used. The viscosity of the resin used is 200 ps,
The curing temperature was 150 ° C. and the curing time was 20 minutes. The thickness of the completed insulating resin film was 10 μm.

Further, the opaque electrode 103, which is a part of the surface electrode, was formed by printing using a conductive resin paste by a screen printing method to obtain a photovoltaic element. As the screen pattern, a parallel line pattern having the same length as the cell length was used as shown in FIG. In the figure, reference numeral 1002 denotes a pattern of the opaque electrode 103. Several types of intervals between parallel lines and thicknesses of the parallel lines were prepared. The alignment between the screen and the substrate was performed in the same manner as in the case of printing the insulating transparent resin described above. The conductive resin paste used is a copper-based paste in which a mixed powder of copper powder and silver powder is dispersed in a resin. Viscosity is 10
It was of 0 ps and the film thickness was 20 μm.

Next, a solder layer (not shown) was formed on the opaque electrode 103. This is to further reduce the resistance of the opaque electrode 103. A solder paste was printed using the screen pattern of FIG. 11 and fired in an oven to form a solder layer. The solder used was eutectic solder. The thickness was 30 μm.

Finally, module terminals were attached by a known method, and vacuum-laminated with a resin on a metal plate to complete the module.

FIG. 8 shows the conversion efficiency (ratio of incident energy to the entire surface of the module and power generation amount) of the module manufactured in this manner. The conversion efficiency was measured using a solar simulator manufactured by Spire. In FIG. 8, the horizontal axis indicates the cell length (element length) of each element, and the vertical axis indicates the normalized efficiency with the maximum conversion efficiency being 1. The value of the conversion efficiency at each cell length was optimized by changing the interval between the parallel lines of the opaque electrode and the thickness of the parallel lines, and showed the highest conversion efficiency at the cell length. FIG. 8 shows that in the case of this example, the maximum conversion efficiency can be obtained with a cell length of about 100 mm. Cell length is 100
When the length is longer than mm, the Joule loss in the surface electrode increases, and the conversion efficiency decreases. Also 100mm
If the distance is shorter, the conversion efficiency decreases because the interval between adjacent elements increases.

Comparative Example 1 As a comparative sample with Example 1, a photovoltaic element module having the configuration shown in FIG. 2 was manufactured as follows.

The insulating support substrate 204 has a width of 30c.
A glass substrate having a length of 1 m, a length of 1 m and a thickness of 5 mm was used. The glass substrate is placed in a vacuum chamber, and a back electrode 2 is
01 was formed. Aluminum was deposited by a sputtering method. The deposition rate was 50 ° / sec for 40 seconds, and the film thickness was 2000 °. In another vacuum chamber, ZnO (not shown) is also
μm.

The deposited back electrode and ZnO layer were separated for each cell by a known laser scribe method. The width of the separation groove was 50 μm. The laser used was a YAG laser.
The cell length was in the range of 2 to 50 m.

Next, a semiconductor layer 202 was formed on the ZnO layer of the separated cell. The formation method is a known CVD method. The layer configuration of the semiconductor layer is the same as that of the first embodiment. Next, a black epoxy-based resin layer having a width of 100 μm was formed on the semiconductor layer in a portion parallel to and separated by 100 μm from the separation groove of the back electrode (not shown). The layer was formed to a thickness of 30 μm by a screen printing method. Further, an ITO layer having a thickness of 700 Å was deposited as a transparent electrode 205 as a part of the surface electrode on the semiconductor layer by the same sputtering method as in Example 1.

Next, as shown in FIG. 2, a separation groove for separating the ITO layer was formed in parallel with the scribe groove of the back electrode at a distance of 100 μm. A YAG laser was used for the formation. The groove width was 50 μm. The black epoxy resin layer serves to protect the semiconductor layer from laser light when the ITO layer is separated, and makes it possible to absorb light in the resin layer and remove the upper ITO layer. ing.

Further, an opaque electrode 203 which is a part of the surface electrode is formed on the transparent electrode made of the ITO layer.
A photovoltaic element was used. The forming method is the same as the screen printing method in the first embodiment. As in the case of the first embodiment, a print pattern in which linear patterns having the same length as the cell length were arranged in parallel was used. The conductive resin paste used is a copper-based paste in which a mixed powder of copper powder and silver powder is dispersed in a resin. The viscosity was 100 ps and the film thickness was 20 μm.

Next, a laser beam is radiated from directly above the opaque electrode to a portion of one of the opaque electrodes of the adjacent element where the back electrode of the other element is located immediately below, and the opaque electrode and the back electrode are welded. Serialized. The laser used was a YAG laser.

Next, a solder paste having the same pattern as that of the opaque electrode was printed on the opaque electrode in the same manner as in Example 1.
It was baked in an oven to form a solder layer (not shown). Finally, module terminals were attached by a known method, and the surface was vacuum-laminated with the same resin as in Example 1 to complete the module.

Example 1 shows the conversion efficiency of the completed module.
8 and the results are shown in FIG. FIG. 8 shows that in the case of this example, the maximum conversion efficiency can be obtained when the cell length (element length) is 15 mm. If the cell length is longer than 15 mm, Joule loss in the back electrode increases, and conversion efficiency decreases. When the cell length is smaller than 15 mm, the number of element isolation grooves increases, and the conversion efficiency decreases.

When the value of the maximum conversion efficiency is compared with that of Example 1, the effect of the present invention is clear. In Comparative Example 1, it is impossible to sufficiently suppress the Joule loss in the back electrode, and the cell length cannot be increased to around 90 mm, which is the same as in Example 1, which is a cause of the low maximum conversion efficiency. .

Also, comparing the output voltage of the module having the highest conversion efficiency of 15 mm with the maximum conversion efficiency of this comparative example and the module having the maximum conversion efficiency of 90 mm of the first embodiment, the module voltage of this example is 118 V. In contrast, the module of Example 1 had a voltage of 20V. From this, it can be seen that the module of the present invention is a module that can be easily insulated and has relatively easy safety measures during construction. Further, the yield of the module when this example was manufactured was 30% worse than that of Example 1. As a result of detailed analysis, 80% of the causes of the failure were poor connection at the connection between the front electrode (opaque electrode) and the back electrode.

Comparative Example 2 Example 1 different from Comparative Example 1
As a comparative sample, a photovoltaic element module having the configuration shown in FIG. 3 was manufactured.

The conductive support substrate 301 has a thickness of 150
A μm SUS plate was used. As in Example 1, a light reflection layer (not shown) and a semiconductor layer 302 were formed on the SUS plate surface by a roll-to-roll method. The light reflecting layer is made of Al and ZnO each having a thickness of 2000Å and 1 μm by sputtering.
m. A semiconductor layer having the same configuration as in Example 1 was manufactured. Further, a transparent electrode 305 was formed on the semiconductor layer in the same manner as in Example 1.

Next, the SUS plate having the light reflecting layer, the semiconductor layer, and the transparent electrode formed on the surface was divided into cells each having a length of 2 to 20 cm using a mold press.

In order to prevent short circuit and short circuit between the transparent electrode of the divided cell and the SUS plate, a width of 0.2 mm
Then, the transparent electrode was removed by a laser scribe method. further,
The semiconductor layer and the transparent electrode immediately above the back electrode at the portion where the serial members 306 and 307 were connected were removed with a laser scribe to a width of 2 mm.

Further, an opaque electrode 303 was formed on the transparent electrode to form a photovoltaic element. Example 1
According to the same screen printing method. As in the case of the first embodiment, a print pattern in which linear patterns having the same length as the cell length were arranged in parallel was used.

The used conductive resin paste is a copper-based paste in which a mixed powder of copper powder and silver powder is dispersed in a resin. The viscosity was 100 ps and the film thickness was 20 μm. Further, a solder layer (not shown) was formed on the opaque electrode by printing using the same screen pattern as that of the opaque electrode in the same manner as in Example 1.

Next, serial members 306 and 307 were separately manufactured. A copper foil (306) having a length of 50 cm, a width of 30 cm, and a thickness of 100 μm is prepared, and has a length of 30 c along the width direction.
An insulating resin strip (307) having a width of 2 mm and a width of 2 mm was formed by screen printing. The strips were printed in a pattern arranged at intervals of 2 mm in parallel with the copper foil length direction.
An epoxy-based thermosetting resin was used as the insulating resin, and was cured by heating after application. The series members were separated by a cutter along the center line between adjacent insulating resin strips to complete the series member. The size of the completed series member is 30 cm in length and 4 mm in width.

The above-described photovoltaic elements were arranged on the table at intervals of 2 mm, and a conductive resin was applied to both ends of each element in the arrangement direction with a dispenser. The conductive resin is applied on the opaque electrode at the end of the element on the low potential side, and on the back electrode at the end where the semiconductor layer and the transparent electrode layer are removed with a width of 2 mm in the element on the high potential side. As the conductive resin, a silver paste having a strong adhesive force to be cured by heating is used. Finally, the series members are bonded between the elements as shown in Fig. 3 so that the center line between the elements and the center line of the series members are aligned, and the module is heated in an oven to cure the conductive resin and complete the serialization. I let it. Finally, a module terminal was attached by a known method, an insulating sheet was laid on a metal plate, the completed series element was mounted thereon, and vacuum-laminated with a resin to complete the module.

Example 1 shows the conversion efficiency of the completed module.
8 and the results are shown in FIG. FIG. 8 shows that in the case of this example, the maximum conversion efficiency can be obtained when the cell length (element length) is 100 mm. If the cell length is longer than 100 mm, Joule loss in the back electrode increases, and conversion efficiency decreases. If the cell length is smaller than 100 mm, the number of cell separation grooves increases and the conversion efficiency decreases.

The effect of the present invention is clear when the value of the maximum conversion efficiency is compared with that of Example 1. The fact that it is impossible to make the gap between cells sufficiently small in Comparative Example 2 is the reason why the highest conversion efficiency equivalent to that of Example 1 is not achieved.

Example 2 As a second example of the present invention, a photovoltaic element module having the structure schematically shown in FIG. 4 was manufactured by the following steps. 4, reference numeral 401 denotes a conductive support substrate serving as a back electrode, 402 denotes a semiconductor layer, and 403 denotes a semiconductor layer.
Is an opaque electrode which is a part of the surface electrode, 404 is a mounting substrate, 405 is a transparent electrode which is a part of the surface electrode, 406 is an extension of the surface electrode, 407 is an insulator, and 408 is a conductor.

This embodiment differs from the first embodiment only in that a metal wire is used for the surface electrode.

That is, the insulating support substrate 401 having a thickness of 1
Using a 5 μm aluminum foil, a light reflecting layer (not shown), a semiconductor layer 402 and a transparent electrode 405 were formed on the surface in the same manner as in Example 1, and cut into cells each having a length of 2 to 20 cm.

Next, as in the first embodiment, the mounting substrate 404
Using a polyimide substrate as the above, the above cells are adhered, and a dozen or more kinds of cells each having a cell width of 2 cm to 20 cm are produced, and in order to prevent contact short-circuit between the transparent electrode and the conductive support substrate. Next, the edge of the transparent electrode was removed by 0.2 mm in width along the edge of the cell.

Further, in the same manner as in Example 1, an insulator 407 was formed at the end of one of the cells that was brought to the lower potential side by serialization between adjacent cells using an insulating transparent resin. Further, a conductive resin was filled between the insulator and an adjacent cell to form a conductor 408. As the conductive resin, a silver paste obtained by dispersing silver fine particles in a thermosetting epoxy resin was used, and the filling was performed by screen printing, followed by curing at 150 ° C. for 20 minutes.

Separately, the opaque electrode 4 which is a part of the surface electrode
03 members were prepared. The member has a diameter of 50 to 500 μ
A copper wire having a thickness of 10 μm is coated on a copper wire having a thickness of 10 μm, and is semi-dried. A plurality of such members were placed in parallel on the transparent electrode on the cell surface as shown in FIG. The heating method is an oven.
This was done by applying pressure with a TFE film. The length of the opaque electrode was the same as the cell length. The opaque electrode was adjusted so that one end was connected to the conductor 408 between cells and did not run on the surface of an adjacent cell. As a result, the series connection between the elements is completed at the same time when each electromotive element is completed. Finally, module terminals were attached by a known method, and vacuum-laminated with a resin on a metal plate to complete a module. A plurality of surface electrodes having different diameters and parallel intervals were produced.

The conversion efficiency of the module thus obtained was measured in the same manner as in Example 1, and the results are shown in FIG. The value of the conversion efficiency at each cell length (element length) was optimized by changing the interval between the parallel lines of the opaque electrode and the thickness of the opaque electrode, and showed the highest conversion efficiency at that cell length. FIG.
From this, it can be seen that in the case of this example, the maximum conversion efficiency can be obtained with a cell length of about 150 mm. If the cell length is longer than 150 mm, the conversion efficiency decreases because the Joule loss in the surface electrode increases. On the other hand, if it is shorter than 150 mm, the conversion efficiency is reduced because the interval between the elements is widened.
When this is compared with Comparative Example 1 and Comparative Example 2, the effect of the present invention is clear.

Further, when this example is compared with Example 1, the cell length showing the highest conversion efficiency is increased from 100 mm to 150 mm, and the cell length is increased. From this, the effect of using a wire for the extension of the surface electrode can be seen.

Example 3 As a third example of the present invention, a photovoltaic module having the structure schematically shown in FIG. 5 was manufactured. In the figure, reference numeral 501 denotes a conductive support substrate serving as a back electrode, 502 denotes a semiconductor layer, 503 denotes an opaque electrode which is a part of a surface electrode, 504 denotes a mounting substrate, 505 denotes a transparent electrode which is a part of a surface electrode, and 506 denotes a transparent electrode. Extension of surface electrode, 507
Is an insulator.

This embodiment differs from the second embodiment only in that a metal wire which is a part of the front electrode is welded to the back electrode of an adjacent element.

The edge of the transparent electrode is set to a width of 0.2 along the cell edge.
The steps before the removal of mm are all the same as in the second embodiment. As shown in FIG. 5, the removal of the transparent electrode involves removing the transparent electrode at the end of the cell which comes in series to the high potential side, as shown in FIG. The transparent electrode was removed along the cell edge with a width of 1 mm.

Thereafter, an insulating transparent resin is used to form an insulator 50 between the adjacent cells at the ends of the cells which come to the lower potential side by serialization.
Steps up to the formation of 7 were performed in the same manner as in Example 2.
In the step of forming the insulator, the printing pattern was changed so that the insulating transparent resin was filled between the cells.

Next, similarly to Example 2, a member for the opaque electrode 503 was separately prepared. A plurality of such members were placed in parallel with each other on the transparent electrode on the cell surface as shown in FIG. The length of the opaque electrode was slightly longer than the cell length. The position of the extension of the surface electrode was adjusted so as to ride an appropriate amount on the surface of the adjacent cell. By irradiating a laser beam from directly above the last surface electrode that was ridden last, and melting and welding a part of the surface electrode, the semiconductor layer, and the back electrode layer, an electric path was formed between the front electrode and the back electrode in that part. .

In the above-mentioned module, a plurality of opaque electrodes having different diameters and parallel intervals were prepared.

The conversion efficiency of the module obtained as described above was measured in the same manner as in Example 1, and the results are shown in FIG. The value of the conversion efficiency at each cell length (element length) was optimized by changing the distance between the parallel lines of the opaque electrode and the thickness of the opaque electrode, and showed the highest conversion efficiency at that cell length. From FIG. 8, it can be seen that in the case of this example, the maximum conversion efficiency can be obtained with a cell length of about 150 mm. Cell length is 150m
When the length is longer than m, the conversion efficiency decreases because the Joule loss in the surface electrode increases. On the other hand, if it is shorter than 150 mm, the conversion efficiency decreases because the distance between the elements increases. When this is compared with Comparative Example 1 and Comparative Example 2,
The effects of the present invention are clear. Further, when this example is compared with Example 2, the effect of connecting the extension of the surface electrode to the end surface of the back electrode (conductive support substrate) of the adjacent element is clear.

Example 4 As a fourth example of the present invention, a photovoltaic element module having a structure schematically shown in FIG. 6 was manufactured. In the figure, 601 is a conductive support substrate as a back electrode, 602 is a semiconductor layer, 603 is an opaque electrode that is a part of a surface electrode, 604 is a mounting substrate, 605 is a transparent electrode that is a part of a surface electrode, and 606 is Extension of surface electrode, 6
07 is an insulator.

The present example is different only in that the supporting substrate of each photovoltaic element has a portion protruding from the end of the semiconductor layer, and an extension of the surface electrode of an adjacent element is connected to the protruding portion. A laser was used to form the protrusion. The output of the YAG laser was set to an appropriate value, the formed semiconductor layer was removed, and the back electrode 601 was exposed.

The output of the obtained module was measured in the same manner as in Example 1, and the results are shown in FIG. When the results of this example are compared with Comparative Examples 1 and 2, the effect of the present invention is clear. In addition, comparing the result of this example with that of Example 1, in this example, the protrusion of the conductive support substrate from the semiconductor layer is an obstacle,
It can be seen that the highest conversion efficiency was reduced due to a decrease in the filling factor of the elements in the module. Therefore, the effect of configuring the conductive support substrate so as not to protrude from the edge of the semiconductor layer is apparent.

Example 5 As a fifth example of the present invention, a photovoltaic element module having the structure schematically shown in FIG. 7 was manufactured. In FIG. 7, reference numeral 701 denotes a conductive support substrate serving as a back electrode, 702 denotes a semiconductor layer, 703 denotes an opaque electrode which is a part of a surface electrode, 704 denotes a mounting substrate, 705 denotes a transparent electrode which is a part of a surface electrode, and 706. Is an extension of the surface electrode, and 707 is an insulator.

In this embodiment, the opaque electrode 703 is formed by changing the printing pattern of the conductive resin from that of the first embodiment. In the opaque electrode of this example, a bus bar for collecting the current collected in each parallel line portion in one place is further formed on the semiconductor layer. In addition, the pattern for removing the transparent electrode along the cell edge was changed so that the portion to which the extended portion of the front electrode was connected was slightly removed, as shown in FIG. Other configurations were the same as in the first embodiment.

The output of the obtained module was measured in the same manner as in Example 1, and the results are shown in FIG. When the results of this example are compared with Comparative Examples 1 and 2, the effect of the present invention is clear. In addition, when the result of this example is compared with Example 1, the highest conversion efficiency is reduced in this example. This is because a portion of the opaque electrode that collects current from each parallel line portion at one location forms a shadow on the semiconductor layer and reduces the effective power generation area. Therefore, the effect of projecting the extension of the surface electrode from a plurality of locations at the end of the semiconductor layer and connecting the extension to the back electrode of an adjacent element is apparent.

Example 6 As a sixth example of the present invention, a photovoltaic element module was manufactured in the same manner as in Example 1 except that a thin film single crystal layer was used for the semiconductor layer.

In this example, a semiconductor layer obtained by mechanically peeling an epitaxial film grown on a single crystal silicon wafer by a liquid phase epitaxy from the wafer was used.

By applying a positive voltage to a 500 μm-thick p ⁺ -type single-crystal silicon wafer immersed in a hydrofluoric acid solution diluted with ethanol, a large number of micropores having a diameter of about several hundred mm were formed on the wafer surface. A porous silicon layer was formed. Further, a thin film single crystal silicon was epitaxially grown on the porous silicon layer by a method called a slow cooling method. 2 growth of the n ⁺ layer of non-doped i-layer and the antimony-doped
The pn junction was completed by performing various types. The thickness of the completed layer is 2
It was 0 μm. Next, the completed thin-film single-crystal semiconductor layer is separated from the porous silicon layer by mechanical vacuum adsorption,
It was thermally fused on an aluminum sheet having a thickness of 15 μm. Further, a transparent electrode was formed on the separated semiconductor layer surface in the same manner as in Example 1. Finally, the aluminum sheet was divided into desired cell sizes by a press machine to obtain unit cells. The subsequent steps are the same as in the first embodiment.

The output of the obtained module was measured in the same manner as in Example 1, and the results are shown in FIG. Each cell length (element length)
Shows the highest conversion efficiency obtained by optimizing the opaque electrode. From FIG. 9, in this example, the cell length is 50 mm
It can be seen that the conversion efficiency is the highest. Cell length is 5
If it is longer than 0 mm, the Joule loss in the back electrode increases, and the conversion efficiency decreases. The cell length is 50m
If it is smaller than m, the number of element isolation grooves increases and the conversion efficiency decreases. In FIG. 9, the highest conversion efficiency obtained among all the manufactured thin-film polycrystalline modules is normalized as 1. Compared with Example 1, the cell length showing the highest conversion efficiency was shorter because the semiconductor layer was a thin film single crystal,
This is because the amount of generated current per unit area has increased.

Comparative Example 3 A module for comparison with Example 6 was manufactured. This example differs from Comparative Example 1 only in that the semiconductor layer is a thin film single crystal. Therefore, the module structure is the same as FIG. The production of a thin film single crystal was performed in exactly the same manner as in Example 6.

The output of the obtained module was measured in the same manner as in Example 1, and the results are shown in FIG.

The effect of the present invention is clear from the comparison between this example and Example 6. Further, it is understood that the effect of the present invention does not depend on the configuration of the semiconductor layer.

(Comparative Example 4) Another module was manufactured for comparison with Example 6. This example is different from Comparative Example 2 only in that the semiconductor layer is a thin film single crystal. Therefore, the module structure is the same as FIG. The production of the thin film single crystal layer was performed in exactly the same manner as in Example 6.

The output of the obtained module was measured in the same manner as in Example 1, and the results are shown in FIG.

The effect of the present invention is clear from the comparison between this example and Example 6. Further, it is understood that the effect of the present invention does not depend on the configuration of the semiconductor layer.

(Example 7) As a seventh example of the present invention, a photovoltaic element module having the same configuration as in Example 2 except that the same thin-film single-crystal semiconductor layer as in Example 6 was used was manufactured. The output of the obtained module was measured in the same manner as in Example 1, and the results are shown in FIG.

The effect of the present invention is clear from the comparison between this example and Comparative Examples 3 and 4. Further, it is understood that the effect of the present invention does not depend on the configuration of the semiconductor layer. When this example is compared with Example 6, the cell length showing the highest conversion efficiency is 50 m.
The cell length has increased from m to 75 mm. From this, the effect of using a wire for the extension of the surface electrode can be seen. Further, it is understood that the effect of the present invention does not depend on the configuration of the semiconductor layer.

Example 8 As an eighth example of the present invention, a photovoltaic element module having the same configuration as in Example 3 except that the same thin film single crystal semiconductor layer as in Example 6 was used was manufactured. The output of the obtained module was measured in the same manner as in Example 1, and the results are shown in FIG.

From the comparison between this example and Comparative Examples 3 and 4, the effects of the present invention are clear. When this example is compared with Example 7, the effect of connecting the extension of the surface electrode to the end surface of the conductive support substrate of the adjacent element is understood. Further, it is understood that the effect of the present invention does not depend on the configuration of the semiconductor layer.

Example 9 As a ninth example of the present invention, a photovoltaic element module having the same configuration as in Example 4 except that the same thin-film single-crystal semiconductor layer as in Example 6 was used was manufactured. The output of the module was measured in the same manner as in Example 1, and the results are shown in FIG.

The effect of the present invention is clear from the comparison between this example and Comparative Examples 3 and 4. Further, it is understood that the effect of the present invention does not depend on the configuration of the semiconductor layer. Further, when this example is compared with Example 6, it is understood that the effect that the conductive supporting substrate does not have a portion protruding from the end of the semiconductor layer is provided.

Example 10 As a tenth example of the present invention, a photovoltaic element module having the same configuration as in Example 5 except that the same thin film single crystal semiconductor layer as in Example 6 was used was produced. The output of the obtained module was measured in the same manner as in Example 1, and the results are shown in FIG.

From the comparison between this example and Comparative Examples 3 and 4, the effect of the present invention is clear. Further, it is understood that the effect of the present invention does not depend on the configuration of the semiconductor layer. Further, when this example is compared with Example 6, it is understood that the extension of the surface electrode protrudes from the end of the semiconductor layer at a plurality of locations and is connected to the conductive support substrate of the adjacent element.

[0150]

According to the present invention, in a photovoltaic element module having a series structure of a plurality of photovoltaic elements, the module efficiency loss can be reduced because the Joule loss at the back electrode of the photovoltaic element is reduced. Is possible.
Further, it is easy to increase the filling rate of the elements by narrowing the element intervals, thereby improving the conversion efficiency and the productivity of the module. Further, since it is easy to reduce the number of photovoltaic elements and to reduce the number of element isolation grooves in the module, the effective power generation area in the module can be further increased to increase the module efficiency. Also, the module output changes from a high-voltage, small-current type to a low-voltage, large-current type because the number of series elements decreases. Therefore, insulation processing is facilitated, and security during construction is easily ensured.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of one embodiment of a photovoltaic element module of the present invention.

FIG. 2 is a diagram schematically showing a configuration of an example of a conventional photovoltaic element module.

FIG. 3 is a diagram schematically showing the configuration of another example of a conventional photovoltaic element module.

FIG. 4 is a diagram schematically illustrating a configuration of a photovoltaic element module according to Embodiment 2 of the present invention.

FIG. 5 is a diagram schematically illustrating a configuration of a photovoltaic element module according to Embodiment 3 of the present invention.

FIG. 6 is a diagram schematically illustrating a configuration of a photovoltaic element module according to Embodiment 4 of the present invention.

FIG. 7 is a diagram schematically illustrating a configuration of a photovoltaic element module according to Embodiment 5 of the present invention.

FIG. 8 is a graph showing the conversion efficiencies of the photovoltaic element modules of Examples 1 to 5, Comparative Example 1, and Comparative Example 2.

FIG. 9 is a graph showing the conversion efficiencies of the photovoltaic element modules of Examples 6 to 10, Comparative Examples 3 and 4.

FIG. 10 is a diagram showing a screen pattern used in a step of forming an insulator in Example 1 of the present invention.

FIG. 11 is a diagram showing a screen pattern used in a step of forming an opaque electrode in Example 1 of the present invention.

[Explanation of symbols]

101, 301, 401, 501, 601, 701 Back electrode (conductive support substrate) 102, 202, 302, 402, 502, 602, 7
02 semiconductor layers 103, 203, 303, 403, 503, 603, 7
03 Opaque electrode (part of surface electrode) 104, 404, 504, 604, 704 Mounting substrate 105, 405, 505, 605, 705 Transparent electrode (part of surface electrode) 106, 406, 506, 606, 706 Surface electrode Extensions 107, 205, 305, 407, 507, 607, 7
07 Insulator 201 Back electrode 204 Insulating support substrate 306 Conductor 307 Insulator 308, 408 Conductor 1001 Insulator pattern 1002 Opaque electrode pattern

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Yoshino 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Koji Tsuzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Within non-corporation (72) Inventor Yoshifumi Takeyama 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 5F051 AA02 BA14 CA14 CB02 CB15 CB28 EA02 EA09 EA11 EA15 FA02 FA04 FA10 FA13 GA02 GA03

Claims (9)

[Claims] 1. A plurality of photovoltaic elements each having at least a semiconductor layer and a surface electrode on a conductive support substrate as a back electrode and arranged and fixed on a mounting substrate via a gap,
A photovoltaic element module having a series structure in which an extension of one surface electrode of adjacent photovoltaic elements is connected to a back electrode of the other photovoltaic element. 2. The photovoltaic element module according to claim 1, wherein said conductive support substrate is made of metal. 3. The photovoltaic element module according to claim 1, wherein said conductive support substrate is made of a foil material. 4. The photovoltaic element module according to claim 1, wherein said semiconductor layer is formed on an entire surface of one surface of said conductive support substrate. 5. The photovoltaic element module according to claim 1, wherein said extension portion is connected to an end surface of said conductive support substrate. 6. The photovoltaic element module according to claim 1, wherein said photovoltaic element has a plurality of extensions of said surface electrode. 7. The photovoltaic element module according to claim 1, wherein an extension of said surface electrode is made of a conductive resin. 8. The photovoltaic element module according to claim 1, wherein an extension of said surface electrode is a metal wire. 9. A plurality of photovoltaic elements having at least a semiconductor layer and a surface electrode on a conductive support substrate with a back electrode serving as a back electrode are arranged and fixed on a mounting substrate via a gap.
A method for manufacturing a photovoltaic element module having a series structure in which an extension of one surface electrode of adjacent photovoltaic elements is connected to a back electrode of the other photovoltaic element,
At least, a step of forming at least a semiconductor layer on a conductive support substrate, a step of dividing the conductive support substrate having at least the semiconductor layer, and a step of fixing the divided conductive support substrate on a mounting substrate, A manufacturing method, comprising: