JP5344595B2 - Solar cell evaluation apparatus, evaluation method, and solar cell manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaluating apparatus and method for a solar battery, which enables accurate evaluation of the solar battery, and also to provide a manufacturing method for the solar battery. <P>SOLUTION: The evaluating apparatus for the solar battery has: a current source 34 which supplies a current to a shunt resistor R<SB>sh</SB>of the solar battery 12 based on a current that flows into the solar battery 12 under a specific bias voltage resulting in a shaded condition; a light source 14 which emits light onto the solar battery 12; a detecting circuit 19 which detects power output from the solar battery 12 that results when light is emitted as the shunt resistor R<SB>sh</SB>is supplied with a current from the current source 34; and a processing unit 20 which calculates the characteristics value of the solar battery 12 based on the result of detection by the detecting circuit 19. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a solar cell evaluation device, an evaluation method, and a solar cell manufacturing method.

  In recent years, the solar cell industry has developed rapidly. In the solar cell factory, solar cell modules (also referred to as solar cell panels) are manufactured. The production scale of solar cells is mostly evaluated by the total amount of generated power. Therefore, if an efficient cell can be obtained even at 1%, the production scale at the solar cell factory will be greatly improved. Naturally, a highly efficient cell has high commercial value.

  Therefore, it is important to evaluate the power generation efficiency of the solar cell. For example, Patent Document 1 discloses a method for measuring efficiency and characteristics of solar cells and the like. In addition, the method of evaluating the output characteristic of a solar cell is disclosed by patent document 2, 3, for example.

Japanese Patent Laid-Open No. 60-83381 JP 2000-196115 A International Publication No. 2008/129010

  The following problems occurred when trying to measure the power generation efficiency distribution by partially illuminating it. A solar cell has a shunt resistance. Therefore, when measuring the power generation efficiency of the solar cell, the current generated in the solar cell flows into the shunt resistor. For example, in a solar cell made of polycrystalline silicon, a shunt resistance is about 100 to 200Ω at about 152.4 mm (= 6 inches) □. For this reason, for example, even if a photoexcitation current of several mA is generated by partial light irradiation, a current greater than the photoexcitation current flows through the shunt resistor under a predetermined bias voltage. That is, the power generated in the solar cell is canceled by the shunt resistance, and accurate measurement cannot be performed.

  The present invention has been made to solve the above-described problem, and an object thereof is to provide a solar cell evaluation apparatus, an evaluation method, and a solar cell manufacturing method capable of accurately evaluating a solar cell. To do.

  The solar cell evaluation apparatus according to the present invention includes a current source that supplies current to a shunt resistor of the solar cell based on an inflow current to the solar cell under a specific bias voltage when light is shielded, and an irradiation to the solar cell. A light source that emits light, a detector that detects the output of the solar cell when light is applied in a state in which a current is passed through the shunt resistor by the current source, and a detection result of the detector And a processing unit for calculating the characteristic value of the solar cell. Thereby, a solar cell can be evaluated correctly.

  Moreover, in the above-described solar cell evaluation apparatus, light conversion means for converting light irradiated to the solar cell from the light source into line-shaped light, and a direction of the line-shaped light with respect to the solar cell Change means for changing, and the processing unit may calculate the power generation efficiency distribution of the solar cell based on a detection result when the linear light is changed in a different direction by the change means. . Thereby, measurement time can be shortened compared with the case where spot light is scanned two-dimensionally.

  Furthermore, in the above-described solar cell evaluation apparatus, the light source includes a plurality of bundle fibers, and the plurality of bundle fibers are arranged in a line shape so that the line light is supplied to the solar cell. It may be irradiated. Thereby, substantially uniform light can be irradiated to a solar cell.

  In the solar cell evaluation apparatus described above, the processing unit may calculate the power generation efficiency distribution by calculating a generated current distribution using an expected value maximizing maximum likelihood estimation method. Thereby, a solar cell can be evaluated more correctly.

  The method for evaluating a solar cell according to the present invention includes a step of passing a current through a shunt resistor of the solar cell based on an inflow current to the solar cell under a specific bias voltage when light is shielded, and irradiating the solar cell with light. A step of detecting an output from the solar cell when light is irradiated in a state where a current is passed through the shunt resistor by the current source, and a characteristic value of the solar cell based on the detection result And a step of calculating. Thereby, a solar cell can be evaluated correctly.

  In the solar cell evaluation method described above, in the step of irradiating the solar cell with light, the linear light is irradiated on the solar cell and the output is detected in the step of detecting the output. Detecting the output from the solar cell when irradiated, and after detecting the output, further comprising the step of changing the linear light to the solar cell in different directions, the linear light being in different directions The power generation efficiency distribution of the solar cell may be calculated based on the detection result of the output from the solar cell. Thereby, measurement time can be shortened compared with the case where spot light is scanned two-dimensionally.

  Furthermore, in the solar cell evaluation method described above, in the step of irradiating the solar cell with light, the solar cell is irradiated with the line-shaped light by arranging a plurality of optical fibers in a line. Also good. Thereby, substantially uniform light can be irradiated to a solar cell.

  In the solar cell evaluation method described above, the power generation efficiency distribution may be calculated by calculating a generated current distribution from the detection result using an expected value maximizing maximum likelihood estimation method. Thereby, a solar cell can be evaluated more correctly.

  Moreover, the manufacturing method of the solar cell concerning this invention has a step which evaluates a solar cell using the above-mentioned evaluation method of a solar cell. As a result, it is possible to find and take measures against a region where the generated current is small, and to improve the productivity of the solar cell.

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell evaluation apparatus which can evaluate a solar cell correctly, the evaluation method, and the manufacturing method of a solar cell can be provided.

It is a perspective view which shows typically the structure of the evaluation apparatus for evaluating the electric power generation efficiency distribution of the solar cell concerning embodiment. It is a side view which shows the structure of the evaluation apparatus concerning embodiment. It is a figure which shows the structure of the illumination intensity measuring device and detection circuit concerning embodiment. It is a circuit diagram which shows the structure of the principal part of the evaluation apparatus concerning embodiment. It is a circuit diagram which shows the structure of the current source concerning an embodiment. It is a circuit diagram which shows the structure of the principal part of the evaluation apparatus at the time of connecting the solar cell concerning embodiment in series. It is a Phantom image of angle division number 2 concerning an embodiment. It is a phantom image of the number of angle divisions concerning an embodiment. It is a phantom image of the number of angle divisions concerning an embodiment. It is a Phantom image of angle division number 16 concerning an embodiment. It is the original image of the density | concentration test image concerning embodiment. It is a density test image of angle division number 8 concerning an embodiment. It is a density test image of the angle division | segmentation number 16 concerning embodiment. It is a density | concentration test image of the angle division | segmentation number 32 concerning embodiment. It is a density | concentration test image of the number of angle divisions 64 concerning embodiment. It is a figure which shows the result of the detail of the density test image of ML-EM of the repetition frequency k = 100 concerning embodiment. It is a figure which shows the result of the detail of the density test image of ML-EM of the repetition frequency k = 100 concerning embodiment. It is a figure which shows the result of the detail of the density | concentration test image of MAP-EM of the repetition frequency k = 100 concerning embodiment. It is a figure which shows the result of the detail of the density | concentration test image of MAP-EM of the repetition frequency k = 100 concerning embodiment. It is a figure which shows the result of the detail of the density test image of ML-EMR of the repetition frequency k = 100 concerning embodiment. It is a figure which shows the result of the detail of the density test image of ML-EMR of the repetition frequency k = 100 concerning embodiment. It is a figure which shows the result of the detail of the density test image of ML-EMR of the repetition frequency k = 1000 concerning embodiment. It is a figure which shows the result of the detail of the density test image of ML-EMR of the repetition frequency k = 1000 concerning embodiment. It is a figure which shows the result of the detail of the density test image of MAP-EMR of the frequency | count of repetition k = 100 concerning embodiment. It is a figure which shows the result of the detail of the density | concentration test image of MAP-EMR of the frequency | count of repetition k = 100 concerning embodiment. It is a figure which shows the result of the detail of the density | concentration test image of MAP-EMR of the frequency | count of repetition k = 1000 concerning embodiment. It is a figure which shows the result of the detail of the density | concentration test image of MAP-EMR of the frequency | count of repetition k = 1000 concerning embodiment. It is a figure which shows each total processing time of the density test image concerning embodiment. It is a figure which shows each processing time when the number of angle division concerning embodiment is constant and the number of pixels of a reconstruction image is changed.

Embodiment.
Embodiments of the present invention will be described below with reference to the drawings. The following description shows preferred examples of the present invention, and the scope of the present invention is not limited to the following examples. In the following description, the same reference numerals denote the same contents.

  The configuration of the evaluation apparatus according to this embodiment will be described with reference to FIGS. 1 and 2. The evaluation device measures the current distribution under a constant bias voltage for predicting the power generation efficiency distribution. That is, the power generation efficiency distribution is obtained by measuring the current distribution. In the following description, such measurement of current distribution is also referred to as measurement of power generation efficiency distribution. FIG. 1 is a perspective view schematically showing the configuration of an evaluation apparatus for evaluating the power generation efficiency distribution of a solar cell. FIG. 2 is a side view showing the configuration of the evaluation apparatus. In FIG. 2, the illustration of the illumination intensity measuring device and the like is omitted.

  As shown in the figure, the evaluation apparatus includes a stage 11, a light shielding plate 13, a light source 14, detection circuits 19 and 25, a processing unit 20, a measurement target driving unit 21, a light shielding plate driving unit 22, an illumination intensity measuring device 23, and an illumination intensity. A measuring instrument driving unit 24 and a roll screen 26 are provided.

  On the stage 11, the solar cell 12 which is a measuring object is mounted. That is, a solar cell 12 to be measured is prepared and placed on the stage 11. The solar cell 12 is, for example, a solar cell module (solar cell panel) composed of one cell. A light source 14 is provided on the solar cell 12. The light source 14 irradiates the solar cell 12 with light. The light source 14 is a solar simulator, for example, and emits illumination light for the solar cell 12. Therefore, light having the same spectrum as sunlight is emitted from the light source 14. The light source 14 is not limited to the solar simulator. Moreover, it is not necessary to make it the spectrum similar to sunlight. Furthermore, the characteristics can be evaluated by changing the wavelength from the light source 14. That is, the wavelength dependence of the output from the solar cell 12 can also be measured.

  Specifically, the light source 14 includes a lamp house 15, bundle fibers 16 and 17, and a housing 18. The lamp house 15 is a lamp house such as a highly stable xenon or halogen lamp. By using a filter, white light from a xenon lamp or the like becomes pseudo sunlight.

  One bundle fiber 16 is connected to the lamp house 15. The bundle fibers 16 and 17 are a bundle of a plurality of optical fibers. One bundle fiber 16 is branched into a plurality of bundle fibers 17. In FIG. 1, the light is branched into four bundle fibers 17. The bundle fibers 17 are arranged in a line on the upper surface of the housing 18.

  The lower end of the housing 18 is attached to the light shielding plate 13 described later. The housing 18 is formed in a trapezoidal columnar shape in which two opposing side surfaces are isosceles trapezoids and the other surface is a quadrangle. The upper surface of the housing 18 is formed in an elongated rectangular shape whose short side corresponds to the diameter of the bundle fiber 17. The housing 18 is open at the lower end and is hollow inside. That is, the lower end of the housing 18 is a rectangular opening. The lower end of the housing 18 is formed in a rectangular shape whose short side is longer than the short side of the top surface and whose long side is substantially the same as the long side of the top surface. That is, the housing 18 has a shape that spreads from the upper side to the lower side. Further, the long sides of the upper surface and the lower end of the housing 18 are sufficiently longer than the size of the solar cell 12.

  Thus, by forming the trapezoidal columnar shape, the light and strong housing 18 can be obtained. As will be described later, the housing 18 moves in the horizontal direction. At this time, if the housing 18 swings, the strength swings and an error occurs. That is, an artifact occurs. For this reason, by making the housing 18 into a trapezoidal columnar shape close to a triangular columnar shape, the above problems can be improved and the measurement accuracy can be improved.

  The bundle fibers 17 are arranged at equal intervals along the long side of the upper surface of the housing 18. For example, the ends of the four bundle fibers 17 are arranged at equal intervals with respect to the length of 100 to 200 mm. That is, the bundle fibers 17 are scattered at a predetermined interval.

  The distance from the upper end of the housing 18 to the lower end of the housing 18 is, for example, about 300 mm. That is, the distance from the end of the bundle fiber 17 to the slit 13a of the light shielding plate 13 is about 300 mm. As a result, the spot-like light is converted into line-like light that is substantially uniform in the long side direction. With such a configuration, light having a spatially uniform intensity is emitted from the light source 14. When measured with the illumination intensity measuring instrument 23 or the like, the amount of light can be suppressed within a range of several percent. If this range is exceeded, even if the power generation efficiency is actually uniform, some power generation efficiency may be measured high. That is, it becomes impossible to accurately measure the power generation efficiency distribution. Further, even though the line-shaped light can be configured with a substantially uniform intensity, it cannot be strictly uniform. Therefore, the intensity distribution may be separately measured by the illumination intensity measuring device 23 and the distribution may be added to the CT calculation described later. In other words, the influence of the illumination unevenness may be reduced by measuring the illumination unevenness with the illumination intensity measuring device 23 and adding it to the CT calculation.

  A light shielding plate 18 b is provided inside the housing 18. The light shielding plate 18b is provided substantially parallel to the light shielding plate 13, and has a slit 18c in part. By providing the slit 18c, it is possible to suppress ghost caused by light reflected from the inner surface of the housing 18. The slit 18c and the slit 13a of the light shielding plate 13 have a predetermined width around the optical axis. The width of the slit 18c is wider than the width of the slit 13a. For example, when the width of the slit 13a is 0.2 mm, the width of the slit 18c is about 5 mm. The light emitted from the bundle fiber 17 passes through the slit 18c and enters the slit 13a. Further, the inner surface of the housing 18 may be painted black. By making the inside of the housing 18 such a configuration, more uniform light can be obtained. The light source 14 is not limited to the above configuration. Further, as long as substantially uniform light can be irradiated, the light does not have to be converted into line-shaped light.

  The light shielding plate 13 is disposed between the light source 14 and the solar cell 12. A slit 13 a is formed in the light shielding plate 13. The light shielding plate 13 is mounted on a belt that can be driven in a horizontal direction (perpendicular to the extending direction of the slit 13a), for example. Hereinafter, the horizontal direction is the x direction, and the extending direction of the slit 13a is the y direction. The belt is provided at each end of the light shielding plate 13 in the y direction. That is, both end portions of the light shielding plate 13 are fixed to the two belts. Each belt is provided so as to surround two pulleys. That is, one pulley is provided at each end of the belt in the x direction. In addition, at each end in the x direction, two pulleys provided on two belts are connected by a connecting shaft. Then, by rotating the connecting shaft and the pulley, the two belts move in the x direction. That is, the light source 14 and the light shielding plate 13 move in the x direction. In other words, the slit 13a moves in the x direction.

  The light from the light source 14 is shielded by the light shielding plate 13, and only the light incident on the slit 13 a enters the solar cell 12. The light irradiated to the solar cell 12 from the light source 14 is converted into line-shaped light by sequentially passing through the slit 18c and the slit 13a. And the solar cell 12 is illuminated by line-shaped light. That is, linear light is irradiated to the solar cell 12.

  The slit 13 a is sufficiently longer than the size of the solar cell 12. Therefore, linear light is irradiated from the end of the solar cell 12 to the opposite end. The width of the slit 13a can be set to, for example, about 0.2 mm. Of course, the width of the slit 13a is not particularly limited and can be appropriately changed.

  A roll screen 26 is disposed on the light shielding plate 13. Specifically, two roll screens 26 are arranged so as to sandwich the light shielding plate 13. Each roll screen 26 covers, for example, from the belt end to the end of the light shielding plate 13 attached to the belt. That is, the outside of the light shielding plate 13 is also shielded by the roll screen 26. Thereby, the solar cell 12 of parts other than just under the slit 13a can fully be light-shielded.

  Moreover, the roll screen 26 is not provided on at least the solar cell 12. That is, the solar cell 12 is not covered with the roll screen 26. Therefore, the light passing through the slit 13a can be scanned onto the solar cell 12 by moving the light shielding plate 13 in the x direction.

  The illumination intensity measuring device 23 moves on the straight guide. Specifically, the illumination intensity measuring device 23 is mounted on a belt. Further, similarly to the above, pulleys and connecting shafts are provided at both ends of the belt. When measuring the light intensity distribution (illumination intensity distribution) from the light source 14, the light source 14 attached to the light shielding plate 13 is disposed on the illumination intensity measuring device 23. That is, the light shielding plate 13 and the light source 14 are disposed on the illumination intensity measuring device 23. In this state, the pulley is rotated. Thereby, the illumination intensity measuring device 23 moves along the y direction. And the light quantity of the light which passed the slit 13a is measured.

  The measurement target drive unit 21 has a rotation mechanism for rotating the solar cell 12. The measurement target drive unit 21 is provided with a motor or the like. The measurement target drive unit 21 rotates the solar cell 12 on the stage 11 by rotating the stage 11, for example. Therefore, the solar cell 12 is rotated by the measurement target drive unit 21. Thereby, the direction of the slit 13a with respect to the solar cell 12 changes. Further, the stage 11 has an axis passing through the center, and the center is difficult to shift. As a result, errors during measurement are unlikely to occur and measurement can be performed accurately. Although the stage 11 is rotated here, the present invention is not limited to this, and the light source 14 and the light shielding plate 13 may be rotated. When the light source 14 and the like are rotated, their centers are not shifted so that the resolution does not decrease.

  The light shielding plate driving unit 22 has a rotation mechanism for moving the light shielding plate 13 in the x direction. The light shielding plate driving unit 22 is provided with a motor and the like. The connecting shaft is rotated by rotating the light shielding plate driving unit 22. As a result, the pulley rotates and the belt moves in the x direction. Then, the light shielding plate 13 attached on the belt and the housing 18 attached on the light shielding plate 13 move in the x direction. Thereby, the slit 13a also moves in the x direction. Specifically, the light shielding plate 13 and the housing 18 move in a direction perpendicular to the long side of the slit 13a. In FIG. 1, the light shielding plate 13 and the housing 18 move in the left-right direction (lateral direction). Thereby, the position of the slit 13a with respect to the solar cell 12 in the x direction changes. In addition, you may attach a linear encoder to a measuring apparatus as needed. Thereby, the coordinate of a x direction can be grasped | ascertained more correctly.

  Thus, the irradiation position of the light in the solar cell 12 is changed by the rotation of the solar cell 12 and the movement of the light shielding plate 13. For example, power is generated at different positions in the cell due to the rotation of the solar cell 12 and the movement of the light shielding plate 13. That is, power generation is performed at different positions of the solar cell 12 depending on the rotation angle of the solar cell 12 and the movement distance of the light shielding plate 13 in the x direction.

  Further, the illumination intensity measuring device driving unit 24 has a rotation mechanism for moving the illumination intensity measuring device 23 in the y direction. The illumination intensity measuring device driving unit 24 is provided with a motor and the like. By driving the illumination intensity measuring device driving unit 24, the connecting shaft rotates. As a result, the pulley rotates and the belt moves in the y direction. Then, the illumination intensity measuring device 23 attached on the belt moves in the y direction. The intensity distribution from one end to the other end of the light passing through the slit 13a can be measured.

  A detection circuit 19 as a detector for detecting the output of the solar cell 12 is connected to the output terminal of the solar cell 12. The detection circuit 19 includes a current-voltage conversion amplifier and a subtraction circuit which will be described later. The detection circuit 19 converts the current from the solar cell 12 into a voltage and outputs the voltage to the processing unit 20. The detection circuit 19 converts and outputs the integrated value of the output in the line-shaped region corresponding to the illumination light.

  A detection circuit 25 as a detector for detecting the output of the illumination intensity measuring device 23 is connected to the output terminal of the illumination intensity measuring device 23. The detection circuit 25 detects the output from the illumination intensity measuring device 23 and outputs it to the processing unit 20.

Here, with reference to FIG. 3, the illumination intensity measuring device 23 and the detection circuit 25 will be described in detail. FIG. 3 is a diagram illustrating the configuration of the illumination intensity measuring device 23 and the detection circuit 25. A non-inverting input terminal (+) and an inverting input terminal (−) of an operational amplifier 27 serving as a detection circuit 25 are connected to the illumination intensity measuring device 23. Further, the non-inverting input terminal (+) of the operational amplifier 27 is grounded, and the feedback resistor R _fb is connected to the inverting input terminal (−) of the operational amplifier 27. The processing unit 20 is connected to the output terminal of the operational amplifier 27.

  When measuring the illumination intensity distribution, the illumination intensity measuring device 23 is irradiated with line-shaped light that has passed through the slit 13 a from the light source 14. The illumination intensity measuring device 23 converts the optical signal into an electrical signal and outputs it to the operational amplifier 27. Further, as described above, the illumination intensity measuring instrument 23 moves along the y direction, and sequentially outputs electric signals to the operational amplifier 27. The output voltage of the operational amplifier 27 changes according to the electrical signal from the illumination intensity measuring device 23. That is, the illumination intensity distribution at an arbitrary wavelength can be measured by the output voltage from the operational amplifier 27.

Here, the illumination intensity measuring device 23 is a photodiode having a sensitivity region of 3 mm × 3 mm. The width of the line-shaped light emitted from the light source 14 is 0.2 mm. The light emitted from the light source 14 is blue-green light having a wavelength of 500 nm, and the light receiving sensitivity of the illumination intensity measuring instrument 23 at this time is 0.3 A / W (sensitivity region 3 mm × 3 mm). For example, when the illumination intensity is 0.1 Sun (10 mW / cm ² ), in order for the output from the operational amplifier 27 to be 1 V, the feedback resistor R _fb may be set to about 556Ω from the following equation (1).

  The processing unit 20 is an information processing apparatus such as a personal computer. The processing unit 20 includes an A / D converter, and converts output voltages from the detection circuits 19 and 25 into digital signals. Then, the processing unit 20 performs a predetermined calculation process on the detection signal. That is, the processing unit 20 is a computer having a storage area such as a CPU or a memory. For example, the processing unit 20 includes a CPU (Central Processing Unit) that is an arithmetic processing unit, a ROM (Read Only Memory) and a RAM (Random Access Memory) that are storage areas, a communication interface, and the like, and generates a power generation efficiency distribution. Perform the processing necessary to measure.

  For example, the ROM stores an arithmetic processing program for performing arithmetic processing, various setting data, and the like. Then, the CPU reads out the arithmetic processing program stored in the ROM and develops it in the RAM. Then, the program is executed in accordance with the setting data and the output from the detection circuit 19 or the like. Further, the processing unit 20 includes a monitor for displaying the calculation processing result.

  Further, the processing unit 20 controls driving of the measurement target driving unit 21, the light shielding plate driving unit 22, and the illumination intensity measuring device driving unit 24. That is, the processing unit 20 controls the rotation angle of these driving units. Therefore, the processing unit 20 grasps the rotation angles of these driving units. The processing unit 20 recognizes the position of the slit 13 a with respect to the solar cell 12. Thus, the processing unit 20 can measure how much output the line-shaped light has when the light enters the solar cell 12. For example, when light is incident on a location where the power generation efficiency is low, the output of the solar cell 12 decreases. Therefore, when the output voltage is low, a line including a portion with low power generation efficiency is illuminated, and when the output voltage is high, a line including a portion with high power generation efficiency is illuminated.

  Next, the operation of the measuring apparatus will be described. First, the solar cell 12 and the slit 13a are aligned. For example, the slit 13a is aligned with one end of the solar cell 12 in the x direction. Then, the light shielding plate 13 is moved in the x direction by the light shielding plate driving unit 22 in a state where light is emitted from the light source 14. Thereby, the slit 13a scans on the solar cell 12 from one end of the solar cell 12 toward the other end. That is, the line-shaped light that has passed through the slit 13 a from the light source 14 scans the solar cell 12. This line-shaped light scans the entire solar cell 12 in the x direction. While the line-shaped light is scanned in the x direction with respect to the solar cell 12, the detection data from the detection circuit 19 is stored in the processing unit 20.

  Then, after the light shielding plate 13 is reciprocated once to return to the initial position, the stage 11 is rotated by the measurement target drive unit 21. Of course, the stage 11 may be rotated by the measurement target drive unit 21 while returning. That is, the detection data is stored in the processing unit 20 while the light shielding plate 13 is moved in one direction. Then, the stage 11 may be rotated while the light shielding plate 13 is moved in the opposite direction. By rotating the stage 11, the solar cell 12 is inclined at a predetermined angle from the state of the solar cell 12 before the stage 11 is rotated. The line-shaped light is scanned over the entire solar cell 12 while being tilted at a predetermined angle. Then, the same operation as described above is repeated to perform measurement for the desired number of angle divisions.

  In addition, when measuring roughly in a short time, the number of angle divisions is about 4, 8, or 16. When more detailed information is obtained over time or artifacts (linear errors called Hansfield dark lines) are reduced, the number of angle divisions is about 64,128. Thus, the number of angle divisions is determined according to the required accuracy and the like.

  The line-shaped light is scanned a plurality of times, and these detection results are stored in the processing unit 20. Thus, the spatial distribution can be measured based on the detection result when the line-shaped light with respect to the solar cell 12 is in a different direction. That is, the angle of the line-shaped light with respect to the solar cell 12 is changed to be two or more directions. And the detection result when 2 or more directions are illuminated is memorize | stored. Then, a spatial distribution of power generation efficiency is obtained for the stored detection result.

  For example, a power generation efficiency distribution spread in two dimensions can be obtained by a computer tomograph (CT). That is, one-dimensional detection data can be converted into a two-dimensional power generation efficiency distribution and imaged. At this time, the X-ray transmission intensity in the X-ray CT corresponds to the output of the detection circuit 19. That is, the linear absorption coefficient of the measurement target in the X-ray CT is the amount of power generated by the line light. The integrated power generation amount for one line becomes projection data. The two-dimensional spatial distribution of the absorption coefficient in the X-ray CT corresponds to the two-dimensional spatial distribution of the power generation efficiency. Thus, the spatial distribution of the power generation efficiency can be calculated by performing the same process as the process of obtaining the tomographic image from the projection data in the X-ray CT with respect to the output current measurement data. That is, a two-dimensional distribution of power generation efficiency can be calculated by the same process as that of the X-ray CT that irradiates collimated X-rays.

  Thus, the output from the solar cell 12 is detected by irradiating the line-shaped light. And the output from the solar cell 12 is detected, changing the direction and position of line-shaped light. The processing unit 20 stores the detection data of this output and performs a predetermined calculation process. Thereby, the spatial distribution of the power generation efficiency can be measured. Therefore, in the solar cell 12, the location where the power generation efficiency is partially reduced can be grasped. And a manufacturing process etc. are optimized so that the power generation efficiency of the location where the power generation efficiency is falling partially may be improved. That is, it is possible to find a region where the generated current is small and take measures. And the solar cell 12 is manufactured using the optimized manufacturing process. In this way, the conditions in the manufacturing process are adjusted based on the measurement result of the power generation efficiency distribution. That is, the solar cell 12 is manufactured by adjusting the conditions in the manufacturing process according to the evaluation result. Thereby, the power generation efficiency of the solar cell 12 can be improved as a whole. Therefore, the productivity of the solar cell 12 can be improved. In addition, if the power generation efficiency of the solar cell 12 is improved, the production scale of the manufacturing plant increases.

  In addition, the measurement time can be shortened as compared with the case of two-dimensional scanning with spot light. That is, when scanning a small spot-like spot, it takes a long time to scan the entire surface of the solar cell 12. As shown in this embodiment mode, the measurement time can be significantly shortened by scanning the line-shaped light. Therefore, productivity can be improved. Furthermore, in the present invention, the power generation efficiency distribution in one cell can be measured by increasing the spatial resolution. Moreover, you may measure a spatial distribution with respect to the solar cell module which consists of a some cell. In the above description, the output from the solar cell 12 is measured when scanning in one direction, but the output from the solar cell 12 may be measured when scanning in both directions.

  Next, the main part of the evaluation apparatus will be described. FIG. 4 is a circuit diagram illustrating a configuration of a main part of the evaluation apparatus.

The solar cell 12 is represented by an equivalent circuit having a current source 31, a diode 32, a parallel resistance (shunt resistance) R _sh , and a series resistance R _s . Light to be scanned is input to the current source 31. That is, as shown in FIGS. 1 and 2, light from the light source 14 that has passed through the slit 13a is input. The shunt resistor R _sh is generated by a leakage current around the pn junction. The series resistance R _s is a resistance when current flows through each part of the element. One terminal of the solar battery 12 is grounded, and the inverting input terminal (−) of the current-voltage conversion amplifier 33 is connected to the other terminal.

A current source 34 is connected between the terminal of the solar cell 12 and the inverting input terminal (−) of the current-voltage conversion amplifier 33. The current source 34 is a current source that supplies current to the shunt resistor R _sh based on the output from the detection circuit when the solar cell 12 is shielded from light. Specifically, in order to set the current (shunt current) from the current source 34, the entire surface of the solar cell 12 is covered and light is completely shielded. That is, light from the light source 14 is not incident on the solar cell 12. In this state, a shunt current is supplied so that the output from the subtraction circuit 35 becomes a desired voltage. For example, the shunt current is adjusted so that the voltage input from the subtraction circuit 35 to the processing unit 20 is about 0V.

When adjusting the shunt current, a bias voltage is applied from the outside of the solar cell 12. This bias voltage is adjusted by controlling the load voltage of the current-voltage conversion amplifier 33. In other words, the current source 34 supplies a current to the shunt resistor R _sh of the solar cell 12 based on the inflow current to the solar cell 12 under a specific bias voltage when completely shielded from light. The shunt current flows through the series resistor R _s and the shunt resistor R _sh . Shunt current make measurements in a state of being supplied to the shunt resistor R _sh, current i _p generated by light irradiation is hardly flows through the shunt resistor R _sh. That is, the current _{i p} flowing from the current source 31 is less likely to flow to the shunt resistor _{R sh.}

The current source 34 is a constant current circuit that allows a constant current to flow if a constant voltage is set. The current source 34 must stabilize the shunt current of the mA order on the order of μA. FIG. 5 is a circuit diagram showing the configuration of the current source 34. In the current source 34 shown in FIG. 5A, a resistor Re is connected to the power supply voltage + V. Further, the other end of the resistor Re, the emitter of the transistor Tr ₁ is connected. By setting the base voltage of the transistor Tr _1, it flows shunt current from the collector of the transistor Tr _1. The shunt current flowing from the current source 34 is reduced by the base current. The voltage at the input terminal of the emitter is the base voltage (current setting voltage) + the base-emitter voltage. That is, the shunt current is (+ V−current setting voltage−base-emitter voltage) / Re.

Current source shown in FIG. 5 (b) 34 further transistor Tr ₂ to the transistor Tr ₁ shown in FIGS. 5 (a) is connected. More specifically, the base of the transistor Tr _1, the emitter of the transistor Tr ₂ are connected. The collector of the transistor Tr ₂ is connected to the power supply voltage, the collector of the transistor Tr ₂ is connected to ground through a resistor. By setting the base voltage of the transistor Tr _2, it flows shunt current from the collector of the transistor Tr _1. The voltage between the base and emitter of the transistor varies depending on the junction temperature. Here, by coupling a transistor Tr ₂ to the transistor Tr _1, the base-emitter voltage cancel. That is, the shunt current is (+ V−current setting voltage) / Re. In this way, accuracy is increased because it is not easily affected by the junction temperature. That is, temperature compensation is performed and accuracy is increased.

  Any of the current sources 34 in FIGS. 5A and 5B can be used for the measuring device, but it is preferable to use the current source 34 in FIG. 5B from the viewpoint of accuracy. Of course, the present invention is not limited to this, and any configuration may be used as long as the current can be set by voltage and stabilized on the order of μA. Further, by using an operational amplifier for the current source 34, it is possible to configure a more accurate constant current circuit.

As described above, the current _{i p} flowing from the current source 31 to become difficult to flow through the shunt resistor _{R sh,} also current _{i p} flows through the feedback resistor _{R fb} of the current-voltage conversion amplifier 33. A subtraction circuit 35 is connected to the output terminal of the current-voltage conversion amplifier 33. The subtraction circuit 35 is a differential amplifier configured by an operational amplifier, for example. The subtraction circuit 35 outputs a difference from V ₋ of the current-voltage conversion amplifier 33. Specifically, the output from the subtraction circuit _35, V + - a _{- (-i p × R fb V} ). In the current-voltage conversion amplifier 33, the inverting input terminal (+) and the non-inverting input terminal (-) are imaginary short. That is, V ₋ = V ₊ . _Therefore, V - - a _{- (-i p × R fb V} ) = i p × R fb. For example, if the bias voltage of the current-voltage conversion amplifier 33 is 0.5, and _{0.5- (0.5-i p × R} fb) = i p × R fb. That is, i _p × R _fb is always output regardless of the bias voltage of the current-voltage conversion amplifier 33.

An output from the subtraction circuit 35 is input to the processing unit 20. That is, the processing unit 20, the output voltage _{(i p} × _{R fb)} is input. The processing unit 20 includes an A / D converter. As a result, the output from the subtraction circuit 35 is converted into a digital signal to perform arithmetic processing. Specifically, the processing unit 20 calculates the power generation efficiency distribution of the solar cell 12 based on the output from the subtraction circuit 35 when the solar cell 12 is irradiated with light in a state where a shunt current is passed.

Further, the processing unit 20 controls the shunt current supplied from the current source 34. The processing unit 20 includes a D / A converter and controls the shunt current by a digital signal. For example, by controlling the base voltage of the transistor Tr ₁ shown in FIG. 5 (a), to control the shunt current. The processing unit 20 controls the shunt current so that the output voltage from the subtraction circuit 35 becomes a desired value when the solar cell 12 is shielded from light.

  Further, the processing unit 20 controls the load voltage at the non-inverting input terminal (+) of the current-voltage conversion amplifier 33. In the present embodiment, the entire solar cell 12 is not irradiated with light at the same time, and the line-shaped light is scanned on the solar cell 12. For this reason, at an arbitrary time, only a part of the solar cell 12 is irradiated with light, and the other part is not irradiated with light. That is, at an arbitrary time, a bias voltage is applied only by a part of the solar cell 12. On the other hand, a bias voltage is applied to the entire solar cell 12 during normal use. Therefore, in the present embodiment, a bias voltage is applied from the outside of the solar cell 12 by applying a load voltage by the processing unit 20. Thereby, even if the other part of the solar cell 12 is dark, if a constant load voltage is applied from the outside, a state similar to that in which the entire solar cell 12 generates power is obtained. And the solar cell 12 can be evaluated correctly.

As described above, the processing unit 20 obtains power generation efficiency by converting the output voltage (i _p × R _fb ) into a digital signal and performing arithmetic processing. Specifically, the processing unit 20 makes the load voltage of the non-inverting input terminal (+) of the current-voltage conversion amplifier 33 constant, and causes the solar cell 12 to scan light. That is, the solar cell 12 is caused to scan light under a constant bias voltage. The constant bias voltage is different from the specific bias voltage applied when adjusting the shunt current. And each detection data scanned is memorize | stored in the process part 20, an arithmetic process is performed, and electric power generation efficiency is calculated | required. The power generation efficiency can be calculated by equation (2).
Here, eta is the power generation _efficiency, the light power incident _{P in} the solar cell 12 (W), V is the output voltage (V), and it is _{I p} is the output current (A). By obtaining the power generation efficiency, the spatial distribution of the power generation efficiency indicating the power generation efficiency distribution can be displayed on the display of the processing unit 20. Further, it is possible to determine the output current i _p, it is also possible to obtain the I-V curve in any point.

Specifically, the processing unit 20 changes the load voltage at the non-inverting input terminal (+) of the current-voltage conversion amplifier 33. Then, by measuring the output current i _p of each load voltage, it is also possible to determine the I-V curve. The maximum output point can be obtained from this IV curve, and the solar cell 12 can be operated efficiently. Moreover, a defect location can be detected from the difference in the maximum output point. For example, when an arbitrary point on the display on which the spatial distribution of power generation efficiency is displayed, an IV curve at that point can be displayed on the display. As described above, the processing unit 20 can calculate not only the power generation efficiency but also various characteristic values such as the IV characteristic.

The measuring apparatus according to the present embodiment has the above configuration. Since current is supplied to the shunt resistor R _sh by the current source 34 and measurement is performed, the current I _p flowing from the current source 31 is less likely to flow to the shunt resistor R _sh . That is, the current _Ip flowing from the current source 31 is output with almost no attenuation. For this reason, it can measure correctly.

  Moreover, the solar cell 12 is measured by sequentially irradiating light. For this reason, at an arbitrary time during the measurement, only part of the solar cell 12 is irradiated with light, and the other part is not irradiated with light. Therefore, during measurement, the output of the point where the light on the solar cell 12 is not irradiated may be read and used as a reference value. Thereby, only the increase in the output due to light irradiation can be accurately measured.

In FIG. 4, the solar cell 12 including one cell is illustrated, but the solar cell 12 in which a plurality of cells are connected in series may be measured. In this case, when the solar cell 12 is considered as a pure photodiode, the impedance due to the shunt resistor R _sh increases in a dark state. For example, as shown in FIG. 6, in the case of the solar battery 12 in which three cells are connected in series, in a dark state, the configuration is such that three shunt resistors R _sh are connected in series. That is, when the shunt resistance R _sh per piece is 100Ω, for example, a configuration in which a 300Ω resistor is connected between the current source 34 and the current-voltage conversion amplifier 33 is obtained.

Therefore, when detecting the output from the solar cell 12 where only a part is irradiated with light as in the present embodiment, it is conceivable that no current can be taken out. However, such a problem is less likely to occur by making the impedance of the feedback resistor R _fb sufficiently larger than the shunt resistor R _sh . For example, the shunt resistance Rsh is about 100Ω, while the feedback resistance is several kΩ.

For the A / D converter of the processing unit 20, for example, a 16-bit input is used in order to obtain sufficient resolution. Since the input range of the 16-bit input A / D converter is several volts, the current-voltage conversion amplifier 33 connected to the A / D converter via the subtraction circuit 35 has the input voltage range set to several volts. Need to be. Therefore, when the amount of light applied to the solar cell 12 is large and the current _Ip from the solar cell 12 increases, the feedback resistance R _fb must be decreased. In the case of the solar battery 12 in which many cells are connected in series, if the feedback resistance R _fb is reduced, it becomes difficult to detect the output for the above reason. From the above, it is preferable to reduce the amount of light applied to the solar cell 12. That is, it is preferable to narrow the width of the slit 13a. Furthermore, by applying a bias voltage to the cells in series, a forward current can be caused to flow through each diode 32, thereby reducing the series resistance. Thereby, measurement accuracy can be raised.

Example.
<algorithm>
The processing unit 20 can image the power generation efficiency distribution spreading in two dimensions from the one-dimensional detection data by computer tomograph (CT). Image reconstruction includes two-dimensional Fourier transform (FFT), filter back projection (FBP), maximum likelihood-expectation maximization (ML-EM), maximum posterior probability maximum likelihood (MAP-) EM: maximum a posteriori-expectation maximization). In these methods, the power generation efficiency distribution is calculated by calculating the generated current distribution. FFT is an analytical image reconstruction method based on the projection section theorem. A one-dimensional Fourier transform G _θ (ξ) for s of a Radon transform g (s, θ) (projection data s in the angle θ direction) of the two-dimensional distribution f (x, y) and f (x, y) The fact that the two-dimensional Fourier coefficients are equal is used. FBP is an analytical reconstruction method that is mathematically equivalent to FFT. For each θ, a filter for multiplying the projection by | ξ | in the frequency space is applied and then back-projected to obtain a reconstructed image.

ML-EM is calculated by the sequential formula shown by Formula (3).

Here, k is the number of repetitions, j is the coordinates 1 to m of the reconstructed image (j = 1 to 16384 if 128 × 128), i is the number 1 to n of the projection data including the angle direction (number of projection directions 4 If the number of data per projection is 128, i = 1 to 512). λ _j is a physical quantity of the pixel j, and C _ij is a ratio (contribution probability) that the pixel _j exerts on the projection data. In this way, by incorporating the physical phenomenon in the actual measurement system into C _ij , a reconstructed image in which this influence is corrected can be obtained. Here, a coefficient by BiLinear interpolation obtained from the positional relationship between the pixel j and the projection data i is used as C _ij . Noise is not taken into consideration.

MAP-EM is represented by the sequential formula shown by Formula (4).

U (λ _j ^k ) is an energy function that represents the influence of the pixel of interest from neighboring pixels. β is a constant that adjusts how well the energy function works. Other terms have the same meaning as described above. Here, β is set to 0.5, and the energy function is expressed as a formula (5) as a method (Median root prior) in which a relative error from the median (center) value in the vicinity of the pixel is given as a weight.
Here, M _j represents a median value of 3 × 3 pixels in the vicinity of the pixel j.

ML-EMR and MAP-EMR (-with Restriction) are methods in which restriction conditions are incorporated into the above-described ML-EM and MAP-EM. Although it is impossible to directly measure the physical quantity λ _j with X-ray CT, SPECT, PET, or the like, it is considered that the physical quantity λ _j of an arbitrary pixel j can be measured with the solar cell power generation efficiency distribution measurement. It was verified whether an image can be reconstructed with better accuracy by incorporating a known physical quantity λ _j into a successive approximation expression as a constraint condition. In this verification, the pixel values on the diagonal are known.

<Phantom image>
Image reconstruction was performed using an image composed of multiple regions with uniform values. The projection angle range was 0 to 180 °, and projection data was acquired at equally spaced angles depending on the number of projections. Sinogram took the coordinates on the axis orthogonal to the projection angle in the width direction and the projection angle in the height direction. In addition, if the number of projection data sampling is n, the measurement object needs to exist inside a circle inscribed in a rectangle of vertical and horizontal size n. An out-of-range image is an incomplete projection and artifacts occur.

  The results of simulation using each method are shown in FIGS. FIG. 7 is a phantom image with angle division number 2 in which the projection angle is 0, 90 °. FIG. 8 is a phantom image with an angle division number of 4 with projection angles of 0, 45, 90, and 135 °. FIG. 9 is a phantom image having an angle division number of 8 with projection angles of 0.0, 22.5, 45.0, 67.5, 90.0, 112.5, 135.0, and 157.5 °. . In FIG. 10, the projection angles are 0, 11.25, 22.50, 33.75, 45.00, 56.25, 67.50, 78.75, 90.00, 101.25, 112.50, 123. It is a phantom image of angle division number 16 which is .75, 135.00, 146.25, 157.50, 168.75 °.

  As shown in FIGS. 7 to 10, in the case of analytical methods (FFT, FBP), analysis was difficult with a small number of projections. Further, since negative values are generated, processing such as cutoff and value stretching is necessary to obtain physical quantities, and the analysis results are further deteriorated when noise is added. Moreover, as shown in FIGS. 7 and 8, in the case of the successive approximation method (ML-EM, MAP-EM, ML-EMR, MAP-EMR), the analysis is difficult when the number of angle divisions is 2 to 4. . However, as shown in FIGS. 9 and 10, when the number of angle divisions is larger than 4, an image close to the original image is obtained. It was found that ML-EM is most preferable because it is difficult to produce artifacts and does not crush small points. Unlike the analytical method, no negative value was generated.

<Density test image>
Next, as shown in FIG. 11, verification was performed assuming detection of a defective portion using an image in which a singular point having a density value of ± 70% in increments of 10% based on the density value 128 is set. . The results of simulation using each method are shown in FIGS. FIG. 12 is a density test image with 8 angular divisions. FIG. 13 is a density test image with 16 angular divisions. FIG. 14 is a density test image having 32 angular divisions. FIG. 15 is a density test image having 64 angle divisions.

  As can be seen from FIGS. 12 to 15, the analytical method showed the same tendency as the phantom image. In the case of the successive approximation method, only a substantially uniform image was obtained when the number of projections was less than 8. Further, in order to detect one pixel of a singular point whose physical quantity is different from the surrounding by about ± 50%, it is considered that projection in 16 to 32 directions is necessary. MAP-EM and MAP-EMR showed relatively good results in the phantom image, but the singularity disappeared in the density test image. This is considered to be due to the fact that an effect close to the median filter (smoothing) is obtained because the difference from the median value is applied to the energy function of MAP-EM. In actual measurement, the influence of noise can be suppressed, but the resolution decreases. From the result of the density test image, ML-EM is considered most preferable.

<Details of density test image>
Next, the reproducibility of singular points by the successive approximation method will be considered. 16 and 17 show the results of ML-EM with the number of repetitions k = 100. 18 and 19 show the results of MAP-EM with the number of repetitions k = 100. 20 and 21 show the results of ML-EMR with the number of repetitions k = 100. 22 and 23 show the results of ML-EMR with the number of repetitions k = 1000. 24 and 25 show the results of MAP-EMR with the number of repetitions k = 100. 26 and 27 show the results of MAP-EMR with the number of repetitions k = 1000.

  The slice graphs shown in FIGS. 16 (a), 18 (a), 20 (a), 22 (a), 24 (a), and 26 (a) are diagonal lines in which singular points are arranged. 4 is a graph in which density values obtained by slicing each image are plotted. In the tables shown in FIG. 16B, FIG. 18B, FIG. 20B, FIG. 22B, FIG. 24B, and FIG. Number of singular points) Rank when the second column is ranked from the smallest total error number, third column is the largest error value, and fourth column is the ranking from the smallest error maximum value Represents.

  FIGS. 17 (c), 19 (c), 21 (c), 23 (c), 25 (c), and 27 (c) show a table of absolute error. In the Absolute Error table, the numerical value in the first row indicates the singular value of the original image. The numerical values in the 2nd to 5th lines represent the absolute value of the difference between the estimated value and the singular value in each angle division number. The numerical value in the sixth line represents the absolute value of the difference between the singular point of the original image and the background value (127). Graphs plotting these tables are shown in FIG. 17D, FIG. 19D, FIG. 21D, FIG. 23D, FIG. 25D, and FIG. It is a graph of Error.

  In the case of MAP-EM and MAP-EMR, as shown in FIGS. 19, 25, and 27, the absolute value of the difference between the estimated value and the singular value was increased overall. Specifically, the difference between the singular point value and the background value substantially coincides, and as shown in FIG. 18A, FIG. 24A, and FIG. Little change was shown. Further, the density value greatly changed at points other than the singular point (both ends in the x-axis direction in the graph). Then, as shown in FIG. 18B, FIG. 24B, and FIG. 26B, the total error and the maximum error value increased.

  On the other hand, in the case of ML-EM and ML-EMR, as shown in FIGS. 17, 21, and 23, the absolute value of the difference between the estimated value and the singular value becomes smaller as the number of angle divisions increases. Specifically, it deviates from the difference between the singular point value and the background value, and as shown in FIGS. 16 (a), 20 (a), and 22 (a), the set density value is set at the singular point. It ’s close. In addition, the change in the density value at points other than the singular point became small. Then, as shown in FIGS. 16B, 20B, and 22B, the total error and the maximum error value are reduced.

<processing time>
FIG. 28 shows the total processing time of each of the density test images. FIG. 28A is a table showing the total processing time in each method for each number of angle divisions. FIG. 28B is a graph obtained by plotting the table of FIG. As shown in FIG. 28, when the pixel value of the reconstructed image is constant, the processing time is substantially linear with respect to the number of angle divisions. Likewise, the number of iterations was linear.

  FIG. 29 shows each processing time when the number of angle divisions is constant (here, eight directions) and the number of pixels of the reconstructed image is changed. In the table of FIG. 29A, the numerical value in the first row represents the length of one side of the reconstructed image, and the numerical value in the second row represents the total number of pixels. The numerical values in the 2nd to 5th lines each represent the processing time for the total number of pixels in the method. FIG. 29B is a graph in which the table of FIG. 29A is plotted. The values of FFT and FBP are the total processing time (unit: ms), and the value of the successive approximation method is the average processing time for one iteration (unit: ms / Iteration). As shown in FIG. 29, when the number of angle divisions is constant, the processing time is linear with respect to the total number of pixels of the reconstructed image.

  Therefore, when ML-EMR processing is performed under the conditions of the number of angle divisions of 16, the reconstructed image size of 1024 × 1024, and the number of repetitions of 500 times, approximately 1196.613 (ms / Iteration) × 500 (Iteration) × (16/8) = 1196.613 (sec) is predicted.

  As can be seen from FIGS. 28 and 29, ML-EM has the shortest processing time among the successive approximation methods. That is, ML-EM is considered to be the most suitable method in terms of analysis accuracy and processing time. By performing arithmetic processing using the ML-EM, the solar cell 12 can be more accurately evaluated.

11 stages, 12 solar cells, 13 light shielding plates, 13a slits, 14 light sources,
15 lamp house, 16 bundle fiber, 17 bundle fiber,
18 housing, 18a slit, 18b light shielding plate, 18c slit,
19 detection circuit, 20 processing unit, 21 measurement target drive unit, 22 light shielding plate drive unit,
23 Illumination intensity measuring device, 24 Illumination intensity measuring device driving unit, 25 Detection circuit,
26 roll screen, 27 operational amplifier, 31 current source, 32 diode,
33 Current-voltage conversion amplifier, 34 Current source, 35 Subtraction circuit

Claims (9)

A current source for supplying a current to the shunt resistor of the solar cell based on an inflow current to the solar cell under a specific bias voltage when shielded from light;
A light source that emits light applied to the solar cell;
A detector for detecting the output of the solar cell when light is applied in a state where a current is passed through the shunt resistor by the current source;
The solar cell evaluation apparatus which has a process part which calculates the characteristic value of the said solar cell based on the detection result in the said detector. A light converting means for converting light irradiated to the solar cell from the light source into line-shaped light;
Change means for changing the direction of the line-shaped light with respect to the solar cell,
The solar cell evaluation apparatus according to claim 1, wherein the processing unit calculates a power generation efficiency distribution of the solar cell based on a detection result when the line light is set in a different direction by the changing unit. The light source has a plurality of bundle fibers,
The solar cell evaluation apparatus according to claim 2, wherein the solar cell is irradiated with the line-shaped light by arranging the plurality of bundle fibers in a line.   4. The solar cell evaluation apparatus according to claim 2, wherein the processing unit calculates the power generation efficiency distribution by calculating a generated current distribution using an expected value maximizing maximum likelihood estimation method. Based on the inflow current to the solar cell under a specific bias voltage when the light is shielded, passing a current through the shunt resistor of the solar cell;
Irradiating the solar cell with light;
Detecting an output from the solar cell when light is irradiated in a state where a current is passed through the shunt resistor by the current source;
A solar cell evaluation method comprising: calculating a characteristic value of the solar cell based on the detection result. In the step of irradiating the solar cell with light, the solar cell is irradiated with line-shaped light,
In the step of detecting the output, the output from the solar cell when the line-shaped light is irradiated is detected,
After detecting the output, further comprising the step of directing the line-shaped light to the solar cell in different directions;
The solar cell evaluation method according to claim 5, wherein the power generation efficiency distribution of the solar cell is calculated based on a detection result of an output from the solar cell when the line-shaped light is in a different direction.   The method for manufacturing a solar cell according to claim 6, wherein, in the step of irradiating light to the solar cell, the line-shaped light is irradiated to the solar cell by arranging a plurality of optical fibers in a line.   The solar cell evaluation method according to claim 6 or 7, wherein the power generation efficiency distribution is calculated by calculating a generated current distribution from the detection result using an expected value maximizing maximum likelihood estimation method.   The manufacturing method of the solar cell which has a step which evaluates a solar cell using the evaluation method of any one of Claims 5 thru | or 8.