JP2005175206A - Solar cell and measuring method of contact resistor and sheet resistor employing solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell capable of measuring the contact resistor of a receiving surface electrode and the sheet resistor of a photoelectric conversion layer under perfected state. <P>SOLUTION: The solar cell is provided with the photoelectric conversion layer, the receiving surface electrode formed on the front surface of the photoelectric conversion layer and a back electrode formed on the rear side of the photoelectric conversion layer, while at least two places of disconnection disconnected with mutually different spaces are formed on the receiving surface electrode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solar battery cell and a method for measuring contact resistance and sheet resistance using the solar battery cell, and more specifically, a contact resistance of a light-receiving surface electrode and a sheet of a photoelectric conversion layer in a solar battery cell in a completed state. The present invention relates to a structure of a solar battery cell for making resistance measurable.

As a prior art related to this invention, a back surface electrode of a solar battery cell is formed with a plurality of divided electrodes, and a solder layer is formed on the surface of each divided electrode by a solder dipping method, whereby a layer is formed at the tip of each divided electrode. A solar battery cell having a thick solder reservoir is known (see, for example, Patent Document 1).
According to such a solar battery cell, when connecting the lead wire to the back electrode in the modularization process, the lead wire is connected to the back electrode with sufficient strength because the lead wire is connected by a plurality of solder reservoirs. Is done.
JP 2000-332269 A

Since it is difficult to measure the contact resistance of the light-receiving surface electrode and the sheet resistance of the photoelectric conversion layer in the completed solar battery cell, it is difficult to obtain correlation data between the resistance value and the cell characteristics.
For this reason, the solar cell which can measure the contact resistance of a light-receiving surface electrode and the sheet resistance of a photoelectric converting layer in the completed state is calculated | required.

  The present invention has been made in consideration of the above-described circumstances. In a completed state, the solar cell capable of measuring the contact resistance of the light-receiving surface electrode and the sheet resistance of the photoelectric conversion layer, and the contact using the solar cell A method for measuring resistance and sheet resistance is provided.

  The present invention includes a photoelectric conversion layer, a light receiving surface electrode formed on the surface of the photoelectric conversion layer, and a back electrode formed on the back surface of the photoelectric conversion layer, and the light receiving surface electrodes are disconnected at intervals different from each other. The present invention provides a solar battery cell in which a disconnection point is formed.

According to the present invention, since the light receiving surface electrode is formed with at least two disconnection locations that are disconnected at different intervals, the electrical resistance values can be measured at the two disconnection locations with different disconnection intervals, respectively. From the difference in value, the contact resistance of the light-receiving surface electrode and the sheet resistance of the photoelectric conversion layer can be obtained.
The obtained contact resistance and sheet resistance are used to obtain correlation data between these resistance values and cell characteristics, and are used for determining the quality of the manufacturing process and for developing solar cells.

  A solar cell according to the present invention includes a photoelectric conversion layer, a light receiving surface electrode formed on the surface of the photoelectric conversion layer, and a back electrode formed on the back surface of the photoelectric conversion layer, and the light receiving surface electrodes are disconnected at different intervals. It is characterized in that at least two disconnected portions are formed.

  In the solar cell according to the present invention, as the photoelectric conversion layer, for example, an n-type or p-type impurity is diffused in a p-type or n-type silicon substrate having a thickness of about 200 to 400 μm to form a pn junction layer. Can be used.

  As the light-receiving surface electrode and the back surface electrode, for example, those formed by printing and baking a metal paste containing metal powder on the front and back surfaces of the photoelectric conversion layer by a method such as a screen printing method can be used.

In the solar battery cell according to the present invention, the light-receiving surface electrode may be composed of two parallel elongated connecting electrodes and a plurality of elongated grid electrodes orthogonal to the connecting electrodes.
Further, in the above configuration, one disconnection point may be formed on each of the two connection electrodes.
Moreover, in the said structure, each disconnection location may be formed in the approximate center of the longitudinal direction of each connection electrode.
Moreover, in the said structure, each disconnection location may be formed so that it may cross each connection electrode diagonally.

  In the solar cell according to the present invention, the light-receiving surface electrode may be made of sintered silver.

  Further, from another viewpoint, the present invention uses the above-described solar cell according to the present invention, and applies the terminals of the resistance meter to the ends of the light receiving surface electrodes facing each other at intervals in each disconnection. Contact resistance and sheet characterized by measuring the electrical resistance value between the end portions and determining the contact resistance of the light receiving surface electrode and the sheet resistance of the photoelectric conversion layer from the difference between the electrical resistance values measured at the two disconnection points, respectively It also provides a method for measuring resistance.

  Further, from another viewpoint, the present invention obtains the contact resistance of the light-receiving surface electrode and the sheet resistance of the photoelectric conversion layer by the contact resistance and sheet resistance measurement method according to the present invention described above, and the obtained contact resistance and The present invention also provides a method for manufacturing a solar battery cell, in which the quality of the manufacturing process of the solar battery cell is determined based on the sheet resistance.

  From another viewpoint, the present invention electrically connects a plurality of solar cells arranged adjacent to each other, and one light receiving surface electrode and the other back surface electrode of a pair of adjacent solar cells. An interconnector to be connected and a sealing material for sealing electrically connected solar cells, each solar cell is composed of the above-described solar cells according to the present invention, The present invention also provides a solar cell module that is connected so as to electrically connect the disconnection points formed on the light receiving surface electrode.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view of a solar battery cell according to Embodiment 1 of the present invention, FIG. 2 is a side view of the solar battery cell shown in FIG. 1, and FIGS. 3 and 4 are process diagrams showing manufacturing steps of the solar battery cell, FIG. 5 is a plan view of a light receiving surface electrode forming screen used when the light receiving surface electrode is formed by a screen printing method, FIGS. 6 and 7 are explanatory diagrams for explaining a method of measuring electric resistance, and FIG. FIG. 9 is a graph showing the relationship between FF and Pm, and FIG. 9 is an explanatory diagram showing a schematic configuration of a solar cell module manufactured using the solar cells shown in FIGS. 1 and 2.

Solar Cell As shown in FIGS. 1 and 2, the solar cell 20 according to Example 1 includes a photoelectric conversion layer 17, a light-receiving surface electrode 14 formed on the surface of the photoelectric conversion layer 17, and a photoelectric conversion layer 17. The back surface collecting electrode 13 formed on the back surface of the light receiving surface electrode 14 is provided, and the light receiving surface electrode 14 is formed with at least two disconnected portions 25 and 26 that are disconnected at different intervals.
The photoelectric conversion layer 17 is obtained by forming the n-type diffusion layer 11 on the surface of the wafer 10 made of p-type silicon.
The light-receiving surface electrode 14 is composed of two parallel elongated connecting electrodes 22 and 23 and a plurality of elongated grid electrodes 24 orthogonal to the connecting electrodes 22 and 23.

The two connection electrodes 22 and 23 each have one disconnection point 25 and 26, and the disconnection points 25 and 26 are connected to the connection electrodes 22 and 23 at approximately the center in the longitudinal direction of the connection electrodes 22 and 23. Are formed so as to cross each of them diagonally.
The antireflection film 12 is formed on the surface of the photoelectric conversion layer 17, the back surface wiring electrode 15 is formed on a part of the back surface collecting electrode 13, and the surfaces of the light receiving surface electrode 14 and the back surface wiring electrode 15 are the solder layer 16. It is covered with.

Production of Solar Cell First, as shown in FIG. 3A, the p-type silicon wafer 10 sliced to 125 mm square and 300 μm thick by a wire saw is subjected to alkali etching to remove a damaged layer at the time of slicing. .
Next, as shown in FIG. 3B, an n-type impurity containing a phosphorus (P) -based compound is applied to the surface of the wafer 10 to be a light receiving surface, and the surface is diffused by thermal diffusion at 800 to 900 ° C. An n-type diffusion layer 11 having a resistance value of about 50Ω is formed.

Next, as shown in FIG. 3C, an SiN film having a film thickness of 70 to 100 μm is formed on the light receiving surface of the wafer 10 as an antireflection film 12 (ARC) by plasma CVD.
Next, as shown in FIG. 3D, an aluminum paste is printed on the back surface of the wafer 10 by a screen printing method, dried at about 150 ° C., and then baked at about 700 to 800 ° C. to become impurities. Aluminum is diffused to form a BSF layer (not shown) made of a P ⁺ layer, and the back collector electrode 13 is formed.
In forming the back surface collecting electrode 13, an opening 13a for forming the back surface wiring electrode 15 (see FIG. 11) is formed in a later step.

Next, as shown in FIG. 3E, a silver paste (viscosity 350 Pa · s (viscosity at 10 rpm)) is printed on the surface of the wafer 10 by a screen printing method to form the light receiving surface electrode 14.
At this time, a light receiving surface electrode forming screen 30 having a mesh pattern corresponding to the light receiving surface electrode to be printed as shown in FIG. 5 is used.
The light receiving surface electrode forming screen 30 shown in FIG. 5 is mainly composed of a frame member 31 having a size of 320 mm × 320 mm, a mesh 32 made of SUS250, and an emulsion 33 integrated with the mesh 32. Only the portion corresponding to the pattern 34 is missing the emulsion 33.

Next, as shown in FIG. 4 (f), a silver paste is printed on the opening 13 a of the back collector electrode 13 by screen printing, dried at about 150 ° C., and then fired at about 700 to 800 ° C. Thus, the back surface wiring electrode 15 is formed. In this firing, the light-receiving surface electrode 14 printed on the light-receiving surface of the wafer 10 fires through the antireflection film 12, and an ohmic contact between the light-receiving surface electrode 14 and the wafer 10 is obtained.
Thereafter, as shown in FIG. 4G, the surface of the light-receiving surface electrode 14 and the back surface wiring electrode 15 is covered with the solder layer 16 by performing solder dipping, and the solar battery cell shown in FIGS. 20 is completed.

Measurement of Contact Resistance and Sheet Resistance Using the completed solar cell 20 shown in FIG. 1, terminals of resistance meters (not shown) are respectively connected to the ends 22a and 22b of the connection electrodes facing each other at a disconnection point 25 with a space therebetween. 2) and the electrical resistance value between the end portions 22a and 22b is measured.
Similarly, also at the disconnection point 26, the resistance values of the terminals 23a and 23b are applied to the ends 23a and 23b of the connection electrodes facing each other with a space therebetween, and the electrical resistance value between the ends 23a and 23b is measured.
At this time, the resistance value measured at the disconnection point 25 includes the contact resistance Rc and the sheet resistance kα as shown in FIG. “K” is a constant, and “α” is a distance between the end portions 22 a and 22 b of the connection electrode 22.
On the other hand, the resistance value measured at the disconnection point 26 includes the contact resistance Rc and the sheet resistance kβ as shown in FIG. “Β” is the distance between the end portions 23 a and 23 b of the connection electrode 23.

Here, when the resistance value between the end portions 22a and 22b of the connection electrode 22 is “R1” and the resistance value between the end portions 23a and 23b of the connection electrode 23 is “R2”, the contact resistance Rc and the sheet resistance kα. , Kβ can be obtained by the following equation.

R1 = 2Rc + kα
R2 = 2Rc + kβ
β> α
R2−R1 = k (β−α)
k = (R2-R1) / (β-α)

R1-kα = 2Rc
Rc = 2Rc / 2

In general, the quality of a solar cell as a product can be judged by the output (Pm). The output (Pm) can be obtained by the following equation.

Pm = Isc × Voc × FF

Here, Isc is a short-circuit current, Voc is an open-circuit voltage, and FF is a filter factor.

FIG. 8 shows the relationship between the sheet resistance value and FF and Pm. In FIG. 8, the sheet resistance value, FF, and Pm of the first sample (T1) are set to 1, respectively, and the sheet resistance value, FF, and Pm of the second sample (T2) and the third sample (T3) are respectively relative. It is a comparison.
As is clear from FIG. 8, as the sheet resistance increases, the FF decreases and the Pm also decreases, so the yield rate decreases.
Although not shown in the graph, the FF tends to decrease as the contact resistance increases.
From these facts, it is possible to determine whether or not the solar cell manufacturing process was satisfactory by measuring the contact resistance and sheet resistance of the solar cell 20 completed by the above-described measurement method.

Solar Battery Module FIG. 9 shows a solar battery module manufactured using the solar battery cell 20 shown in FIGS. 1 and 2.
The solar cell module 60 shown in FIG. 9 includes a plurality of solar cells 20 arranged so as to be adjacent to each other, one light receiving surface electrode 14 of the pair of adjacent solar cells 20 and the other back surface wiring electrode 15. The interconnector 61 and the sealing material 62 for sealing the electrically connected solar cells 20 are formed on the light receiving surface electrode 14 of each solar cell 20. The disconnected part 25 is connected so as to be electrically connected.
Although not shown in the figure, the disconnected portion 26 is also electrically connected by the interconnector 61 in the same manner.

A light receiving surface glass 63 is attached to the front surface side of the sealing material 62, and a back surface sealing sheet 64 is attached to the back surface side, and the outer edge of the sealing material 62 is surrounded by an aluminum frame member 65. .
Note that an external terminal 66 for extracting power is connected to the light receiving surface electrode 14 and the back surface wiring electrode 15 of the solar battery cell 20 located at both ends.
In other words, the solar battery cell 20 is put to practical use in the same manner as a general solar battery cell in which a disconnection point is not formed by electrically connecting the disconnection points 25 and 26 of the light receiving surface electrode 14 with the interconnector 61.

A solar battery cell according to Embodiment 2 of the present invention will be described with reference to FIGS.
In Example 2, the light receiving surface electrode forming screen 50 shown in FIG. 10 is used in place of the light receiving surface electrode forming screen 30 shown in FIG.
For this reason, as shown in FIG. 11, the light receiving surface electrode 41 of the completed solar battery cell 40 is formed with disconnection portions 45, 46, 47, 48 at four locations.
The disconnection points 45 and 46 are formed on the connection electrode 42, and the disconnection points 47 and 48 are formed on the connection electrode 43.
The disconnection points 45 and 46 formed in the connection electrode 42 and the disconnection points 47 and 48 formed in the connection electrode 43 have the same disconnection interval.

  In the measurement of the electrical resistance value, as shown in FIG. 11, the end portions 42a and 42b of the connection electrodes facing each other at the disconnection location 45, the end portions 42c and 42d of the connection electrodes facing each other at the disconnection location 46, and the disconnection location. 47, the resistance values are measured by applying the terminals of the resistance meter to the ends 43a and 43b of the connection electrodes facing each other and the ends 43c and 43d of the connection electrodes facing each other at the disconnection point 48.

That is, in Example 2, since the number of measurement points is increased to four, more accurate contact resistance and sheet resistance can be calculated.
For example, by calculating the average value of the contact resistance obtained from the difference between the resistance values of the breakage point 45 and the breakage point 46 and the contact resistance obtained from the difference between the resistance values of the breakage point 47 and the breakage point 48, Accurate contact resistance can be calculated.
Similarly, by obtaining the average value of the sheet resistance obtained from the difference in resistance value between the breakage point 45 and the breakage point 46 and the sheet resistance obtained from the difference in resistance value between the breakage point 47 and the breakage point 48, More accurate sheet resistance can be calculated.

It is a top view of the photovoltaic cell by Example 1 of this invention. It is a top view of the photovoltaic cell shown by FIG. It is process drawing which shows the manufacturing process of the photovoltaic cell shown by FIG. 1 and FIG. It is process drawing which shows the manufacturing process of the photovoltaic cell shown by FIG. 1 and FIG. It is a top view of the screen for light-receiving surface electrode formation used at the manufacturing process of FIG.4 (e). It is explanatory drawing explaining the measuring method of contact resistance and sheet resistance. It is explanatory drawing explaining the measuring method of contact resistance and sheet resistance. It is a graph which shows the relationship between sheet resistance, FF, and Pm. It is explanatory drawing which shows schematic structure of the solar cell module manufactured using the photovoltaic cell shown by FIG. 1 and FIG. It is a top view of the screen for light-receiving surface electrode formation used at the manufacturing process of the photovoltaic cell by Example 2 of this invention. It is a top view of the photovoltaic cell by Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Wafer 11 ... N-type diffused layer 12 ... Antireflection film 13 ... Back surface collection electrode 13a ... Opening part 14 ... Light-receiving surface electrode 15 ... Electrode for back surface wiring 16. ..Solder layer 17 ... Photoelectric conversion layer 20 ... Solar cell 22,23,42,43 ... Connecting electrode 22a, 22b, 23a, 23b, 42a, 42b, 42c, 42d, 43a, 43b , 43c, 43d ... end 24 ... grid electrode 25, 26, 45, 46, 47, 48 ... disconnection location 30, 50 ... light receiving surface electrode forming screen 31 ... frame material 32 ... Mesh 33 ... Emulsion 34 ... Mesh pattern 60 ... Solar cell module 61 ... Interconnector 62 ... Sealing material 63 ... Light receiving surface glass 64 ... Back side sealing sheet 65 ... Wood 66 ... external terminal

Claims (9)

  A photoelectric conversion layer, a light-receiving surface electrode formed on the surface of the photoelectric conversion layer, and a back-surface electrode formed on the back surface of the photoelectric conversion layer, the light-receiving surface electrode is formed with at least two disconnected points disconnected at different intervals A solar battery cell characterized by being made.   The solar cell according to claim 1, wherein the light-receiving surface electrode includes two elongated connection electrodes in parallel and a plurality of elongated grid electrodes orthogonal to the connection electrodes.   The solar cell according to claim 2, wherein the disconnection portion is formed on each of the two connection electrodes.   The method for measuring contact resistance and sheet resistance of a solar battery cell according to claim 3, wherein each disconnection point is formed at substantially the center in the longitudinal direction of each connection electrode.   5. The solar battery cell according to claim 3, wherein each disconnection portion is formed so as to obliquely cross each connection electrode.   The solar cell according to any one of claims 1 to 5, wherein the light-receiving surface electrode is made of sintered silver.   Using the solar battery cell according to any one of claims 1 to 6, a terminal of an ohmmeter is applied to each end of the light receiving surface electrode facing each other at an interval at each disconnection point, and between the ends. A method for measuring contact resistance and sheet resistance, characterized in that the electrical resistance value is measured, and the contact resistance of the light-receiving surface electrode and the sheet resistance of the photoelectric conversion layer are respectively determined from the difference between the electrical resistance values measured at two disconnection points. .   The contact resistance of the light receiving surface electrode and the sheet resistance of the photoelectric conversion layer are respectively determined by the contact resistance and sheet resistance measuring method according to claim 7, and the quality of the solar cell manufacturing process is determined based on the obtained contact resistance and sheet resistance. The manufacturing method of the photovoltaic cell characterized by distinguishing.   A plurality of solar cells arranged adjacent to each other, an interconnector that electrically connects one light receiving surface electrode and the other back surface electrode of a pair of adjacent solar cells, and an electrically connected solar And a solar cell according to any one of claims 1 to 6, wherein an interconnector is formed on a light-receiving surface electrode of each solar cell. Solar cell module connected to electrically connect the disconnected part.

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