TWI448705B - Solar cell testing system, testing method, and multifunctional testing light source - Google Patents

Description

Solar cell test system, test method, and multi-function test light source

The invention relates to a solar cell, in particular to a solar cell test system, a test method, and a multifunctional test light source.

Since the minerals (such as crude oil and coal mines) that can be used for power generation on the earth have been rapidly depleted, and the way of thermal power generation will continue to exacerbate global warming, the development and promotion of sustainable alternative energy sources has become an urgent task for human beings. Among various alternative energy sources, solar cells are considered to be more popular.

At present, not only do operators try to improve the conversion efficiency of solar cells, but also the conversion efficiency is used as a criterion for evaluating the quality of solar cells. For example, a conversion efficiency difference of 0.2% can lead to significant price differences. To test the conversion efficiency of solar cells, artificial light sources are typically used to simulate sunlight defined as AM 1.5G. Specifically, this artificial light source is used to simulate the incidence of sunlight at about 48.2 degrees from the top of the head. However, it is actually difficult to call up a light source whose illumination state is consistent with the standard AM 1.5G spectrum, so the tolerance on the error is also large. For example, in the specification of IEC60904-9, the error of each band is 25%. It can be defined as a Class A light source. Under this type of specification, there may be considerable differences between several AM 1.5G artificial light sources that are also classified as Class A. For example, some Class A AM 1.5G artificial light sources may have stronger blue light. Energy, some A-class AM 1.5G artificial light sources have stronger energy in red light. It is conceivable that the use of these Class A light sources to classify solar cells with a classification pitch of 0.2% is likely to cause a gradation error.

Regardless of whether multiple solar cells are tested using the same or multiple Class A sources, even though the results of the tests show that two solar cells have similar conversion efficiencies, the spectral responses of the two solar cells may be different on different bands. For example, one of them responds better to blue light, and the other responds better to red light. If the two solar cells are connected in series in the same solar cell module, whether in a strong blue light or a strong red light environment, the two solar cells will be constrained by the difference between the two spectral responses. So that the expected electrical energy cannot be produced.

To avoid misclassification, manufacturers can additionally test the spectral response of solar cells to infer their quantum efficiency (QE). However, the conventional spectral response measurement method often has a problem of too slow speed and high cost, so it cannot be widely used in a solar cell production line.

Therefore, for solar cell suppliers, it is necessary to have not only an artificial light source with a small difference from AM 1.5G but also a small difference between the machines, but also a test system capable of measuring the spectral response of the solar battery at high speed and low cost. method.

One of the objects of the present invention is to provide a solar cell test system, a test method, and a multi-function test light source to solve the above problems.

The embodiment of the invention discloses a solar cell testing system, comprising: a multi-function test light source, a measuring unit, and an arithmetic unit. The multi-function test light source is used to output a simulated sunlight to the solar cell and asynchronously output a variety of narrow-band light to the solar cell. The measuring unit is coupled to the solar cell for measuring the response of the solar cell to the simulated sunlight and the response to a plurality of narrow-band lights. The computing unit is coupled to the multi-function test light source and the measuring unit for calculating the conversion efficiency and spectral response of the solar cell according to the response of the solar cell to the simulated sunlight and the response to a plurality of narrow-band lights.

The embodiment of the invention further discloses a multi-function test light source, comprising: a light-emitting diode array comprising a plurality of light-emitting diodes; a light mixing system; and a driving unit coupled to the light-emitting diode array A plurality of light-emitting diodes are driven to output a simulated sunlight through the light mixing system, and a plurality of light-emitting diodes are driven to non-synchronously output a plurality of narrow-band lights through the light mixing system.

The embodiment of the invention further discloses a solar cell testing method, comprising: driving a multi-function test light source to output a simulated sunlight to a solar cell, and measuring the response of the solar cell to the simulated sunlight; driving the multifunctional test source to be asynchronous Output a variety of narrow-band light to the solar cell, and measure the response of the solar cell to a variety of narrow-band light; and calculate the conversion efficiency and spectral response of the solar cell based on the response of the solar cell to the simulated sunlight and the response to a plurality of narrow-band lights.

Please refer to Figure 1. 1 is a functional block diagram of a solar cell test system 100 in accordance with an embodiment of the present invention. The solar cell test system 100 of the present embodiment includes a multi-function test light source 110, a measurement unit 150, and an operation unit 160 for testing a solar cell 190. The multi-function test light source 110 is composed of a driving unit 120, a light emitting diode (LED) array 130, and a light mixing system 140. Briefly, on the production line, the solar cell test system 100, which is a single set of hardware devices, can quickly measure the conversion efficiency and spectral response of each solar cell 190, and the solar cell test system 100 is also used due to the use of LEDs as a light source. It has the advantages of long life and low power consumption.

The LED array 130 includes a plurality of different LEDs, and any of the LEDs may include one or more LEDs of the same type, and different LEDs may use different driving signals. The driving unit 120 can drive some or all of the LEDs in the LED array 130 to simultaneously emit light to output the simulated sunlight required for measuring the conversion efficiency of the solar cell 190, and can also drive different types of LEDs in the LED array 130 to be asynchronous (asynchronously, That is, not necessarily simultaneously, the plurality of narrowband lights required to measure the spectral response of the solar cell 190 are measured at a non-synchronous output. For example, in order to accurately simulate the AM 1.5G sunlight, the LED array 130 may include at least one white LED and at least ten narrow-band LEDs, and the narrow-band light may be defined as visible or invisible light having a frequency bandwidth of less than 100 nm. If a narrow-band light is visible light, it may have a specific color instead of white. The table of FIG. 2 lists the specifications of various types of LEDs in the LED array 130.

The light mixing system 140 is used to uniformly illuminate the light generated by the LED array 130 on the solar cell 190. The upper surface of the solar cell 190 may be directly connected to the LED array 130, and the four inner sides may be formed by a four-sided silver mirror. The lower surface of the solar cell 190 may include a beam splitter and a brightness enhancement film.

By measuring the first electrical signal (which may be a voltage and/or current signal) generated by the solar cell 190 being irradiated by simulated sunlight, the measuring unit 150 may obtain a response of the solar cell to the simulated sunlight; The solar cell 190 is subjected to a second electrical signal (which may be a voltage and/or a current signal) generated by a plurality of non-synchronous illumination of narrow-band light, and the measuring unit 150 may derive a response of the solar cell to various narrow-band lights. The computing unit 160 can be a computer. The computing unit 160 can calculate the conversion efficiency and spectral response of the solar cell 190 according to the response of the solar cell 190 to the simulated sunlight and the response to various narrow-band lights. Further, the arithmetic unit 160 may estimate the quantum efficiency, the energy gap, and/or the carrier diffusion length of the solar cell 190 based on the spectral response. The arithmetic unit 160 can also use the spectral response of the solar cell 190 to individually correct the measurement error of the conversion efficiency.

Since different kinds of LEDs in the LED array 130 can use different driving signals, when driving a plurality of different LEDs in the LED array 130 to simultaneously emit light to generate simulated sunlight, the driving unit 120 can adjust the driving currents supplied to different kinds of LEDs and / or duty cycle, so that the spectral distribution of simulated sunlight is very close to the spectral distribution of AM1.5G, in fact, the spectral mismatch of simulated sunlight compared to the spectral distribution of AM1.5G In addition to the A grade of IEC60904-9, even the error of each band will fall within 5%. In addition, the difference between simulated sunlight generated by the multi-function test light source 110 of different machines can also converge to a minimum. Therefore, even if a plurality of solar cell test systems 100 are used to test a plurality of solar cells 190, it is less likely to cause a gradation error.

In order to allow the test system 100 to quickly measure the response of the solar cell 190 to a variety of narrow-band lights, the test system 100 may also employ a code division multiple access (CDMA) technology. For example, the driving unit 120 may include a CDMA encoder 125 for providing a plurality of sets of mutually orthogonal codes as a basis for driving the plurality of narrow-band optical LEDs in the LED array 130 by the driving unit 120; The unit 150 can include a CDMA decoder 155 for decoding the response of the solar cell 190 to any of the narrowband lights from the second electrical signal using the plurality of sets of mutually orthogonal codes.

For example, if the solar cell 190 is to measure the response of the 16 narrow-band lights provided by the 16 narrow-band light LEDs listed in FIG. 2, the plurality of sets of mutually orthogonal codes may be 16 groups. The 16 sets of codes can be 16 columns of a 32 x 32 Walsh-Hadamard Matrix. The number of rows and rows of the Huaxu matrix are 2 ^k , k is an integer, the value in the matrix is not +1 or -1, and the remaining (2 ^k -1) column after deducting the first column of +1 is It is a (2 ^k -1) group of mutually orthogonal codes. The following 2 × 2 Hua Xu matrix, 4 × 4 Hua Xu matrix, and 2 ^k × 2 ^k Hua Xu matrix are listed:

The following are examples of 16 sets of mutually orthogonal codes shared by CDMA encoder 125 and CDMA decoder 155:

a ₁ =[1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1]

a ₂ =[1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1]

a ₃ =[1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 - 1 1]

a ₄ =[1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1]

a ₅ =[1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 - 1 1]

a ₆ =[1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 1]

a ₇ =[1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -1]

a ₈ =[1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1]

a ₉ =[1 -1 1 -1 1 -1 1 -1 -1 1 -1 1 -1 1 -1 1 1 -1 1 -1 1 -1 1 -1 -1 1 -1 1 -1 1 - 1 1]

a ₁₀ =[1 1 -1 -1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 -1 -1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1]

a ₁₁ =[1 -1 -1 1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1 1 -1 -1 1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1]

a ₁₂ =[1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 1 1 1]

a ₁₃ =[1 -1 1 -1 -1 1 -1 1 -1 1 -1 1 1 -1 1 -1 1 -1 1 -1 -1 1 -1 1 -1 1 -1 1 1 -1 1 -1]

a ₁₄ =[1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 -1 -1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 -1 -1]

a ₁₅ =[1 -1 -1 1 -1 1 1 -1 -1 1 1 -1 1 -1 -1 1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -1 1 -1 - 1 1]

a ₁₆ =[1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1]

In terms a _i (n) value to the n th code of the set a _i, wherein i is a positive integer between 1 and 16, n is a positive integer between 1 and 32, the following three formulas are Will be established

a _i (n) a _j (n)=0; j is a positive integer between 1 and 16 but not equal to i.

The driving unit 120 can use the set of codes _ai as the basis for driving any number of LEDs of the i-th narrow-band optical LEDs in the LED array 130. Since each code has 32 values, the driving unit 120 needs to cut the period of driving the LED array 130 into 32 points, including T ₁ , T ₂ , T ₃ , ..., T _{32 for} a total of 32 sub-periods. If a _i (n)=+1, it means that the driving unit 120 illuminates one or more LEDs of the i-th narrow-band light LED in the LED array 130 in the sub-period T _n ; if a _i (n)=-1 , indicating that the driving unit 120 does not illuminate the i-th narrow-band light LED in the LED array 130 during the sub-period T _n .

If the lighting in the LED array 130 i-th narrowband light from the LED 190 will cause the solar cell to generate a light intensity of the current _i L, then the sub-periods T _n solar cell 190 by the i-th LED light narrowband impact of The photocurrent L _i (n) will be l _i × 1/2 × [a _i (n) +1)], that is, when a _i (n) = +1, L _i (n) = l _i ; When a _i (n) = -1, L _i (n) = 0. The total photocurrent L(n) generated by the solar cell 190 under the influence of 16 kinds of narrow-band light LEDs in the sub-period T _n will be {l _i × 1/2 × [a _i (n) +1]}.

For any positive integer j between 1 and 16, the following expression will hold.

Since L(n) is the second electrical signal measured by the measuring unit 150, a _j (n) is a known value for the CDMA decoder 155, so that the CDMA decoder 155 can obtain the point by the above formula. The jth narrow-band light LED in the bright LED array 130 causes the photocurrent l _j generated by the solar cell 190. Since j can be any positive integer between 1 and 16, the CDMA decoder 155 can derive the photocurrent generated by the solar cell 190 caused by lighting any of the narrowband light LEDs in the LED array 130. Since the luminous intensity of various narrow-band light LEDs and the wavelength bands of various narrow-band light LEDs are known, the arithmetic unit 160 can calculate the spectral response of the solar cell 190 according to the data provided by the measuring unit 150.

Since each of the above codes has a value of +1 and -1 in each half, during the decoding process, half of the ambient light is multiplied by +1 to join the statistics, and the other half is multiplied by -1 to join the statistics. Offset, the test system 100 is less susceptible to ambient light when measuring the spectral response of the solar cell 190.

In summary, the single-set hardware device of the solar cell test system 100 can not only provide accurate simulated sunlight to measure the conversion efficiency of the solar cell 190, but also quickly measure the spectral response of the solar cell 190, and different machines. The difference between the stations can be minimized. Each machine has a long life and low power consumption. Therefore, it can be applied to the production line to accurately classify the mass-produced solar cells 190 to ensure that each battery is modularized. The maximum power generation efficiency can still be achieved.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100. . . Solar cell test system

110. . . Multi-function test light source

120. . . Drive unit

125. . . Encoder

130. . . Light-emitting diode array

140. . . Mixed light system

150. . . Measuring unit

155. . . decoder

160. . . Arithmetic unit

190. . . Solar battery

1 is a functional block diagram of a solar cell test system in accordance with an embodiment of the present invention.

The table of Figure 2 lists the specifications of the various LEDs included in the LED array of Figure 1.

100. . . Solar cell test system

110. . . Multi-function test light source

120. . . Drive unit

125. . . Encoder

130. . . Light-emitting diode array

140. . . Mixed light system

150. . . Measuring unit

155. . . decoder

160. . . Arithmetic unit

190. . . Solar battery

Claims (7)

A solar cell test system includes: a multi-function test light source for outputting a simulated sunlight to a solar cell and asynchronously outputting a plurality of narrow-band lights to the solar cell, wherein the multi-function test light source comprises: a light emitting a diode array comprising a plurality of light emitting diodes; a light mixing system disposed between the light emitting diode array and the solar cell; and a driving unit coupled to the light emitting diode array for Driving the plurality of light emitting diodes to output the simulated sunlight through the light mixing system, and driving the plurality of light emitting diodes to asynchronously output the plurality of narrowband lights through the light mixing system; a measuring unit coupled to the solar energy a battery for measuring the response of the solar cell to the simulated sunlight and the response to the plurality of narrow-band lights; an arithmetic unit coupled to the multi-function test light source and the measuring unit for using the solar cell Calculating the conversion efficiency and spectral response of the solar cell in response to the simulated sunlight and the response to the plurality of narrow-band lights; and wherein the drive list An encoder is provided for providing a plurality of sets of mutually orthogonal codes as a basis for the driving unit to drive the plurality of light emitting diodes to asynchronously output the plurality of narrowband lights, and the measuring unit includes a decoder for using The plurality of sets of mutually orthogonal codes decode the response of the solar cell to any of the plurality of narrowband lights from the response of the solar cell to the plurality of narrowband lights. The test system of claim 1, wherein the light emitting diode array comprises at least one white light emitting diode and at least ten narrow frequency light emitting diodes. A multifunctional test light source comprising: An array of light emitting diodes includes a plurality of light emitting diodes; a light mixing system; and a driving unit coupled to the light emitting diode array for driving the plurality of light emitting diodes to output through the light mixing system Simulating sunlight, and driving the plurality of light emitting diodes to asynchronously output a plurality of narrowband lights through the light mixing system, wherein the driving unit includes an encoder for providing a plurality of sets of mutually orthogonal codes for driving the driving unit The plurality of light-emitting diodes asynchronously output the basis of the plurality of narrow-band lights. The test light source of claim 3, wherein the light emitting diode array comprises at least one white light emitting diode and at least ten narrow frequency light emitting diodes. A solar cell testing method includes: driving a multi-function test light source to output a simulated sunlight to a solar cell, and measuring a response of the solar cell to the simulated sunlight; driving the multi-function test light source to have a plurality of non-synchronous outputs Frequency light to the solar cell, and measuring the response of the solar cell to the plurality of narrow-band lights; and calculating the conversion efficiency of the solar cell according to the response of the solar cell to the simulated sunlight and the response to the plurality of narrow-band lights And spectral response. The test method of claim 5, wherein the multifunctional test light source comprises an array of light emitting diodes, the light emitting diode array comprising at least one white light emitting diode and at least ten kinds of narrow frequency light emitting Diode. The test method of claim 6, further comprising: using a plurality of sets of mutually orthogonal codes as a basis for driving the plurality of narrow-band light-emitting diodes to asynchronously output the plurality of narrow-band lights; and using the same Multiple sets of mutually orthogonal codes to decode the response of the solar cell to the plurality of narrowband lights from the solar cell to any of the plurality of narrowband lights response.