TW200944820A - Measurement method for internal series resistance of solar cell and measuring system of the same - Google Patents

Abstract

The invention discloses a measurement method for internal series resistance of solar cell and measuring system of the same, by i applying a reverse current to the solar cell to replace the second illumination process during a double illumination measurements used in the prior art. The reduced illumination processes not only decrease the consumption time to speed up measurement efficiency and conform to the solar cell escalating requirement in current marketplace, but also prolong the lifetime of light source. Furthermore, the simplification of illumination for the light source ensures the accuracy of measurement the maintenance and repair requirements is reduced and operation cost are lower, so that the measurement of solar cell will be more efficient.

Description

200944820 IX. Description of the Invention: [Technical Field] The present invention relates to a resistance measuring method, and more particularly to a method and a measuring system for measuring internal series resistance of a solar battery. [Prior Art] The main types of PN type solar cells can be classified into single crystal germanium, polycrystalline germanium and amorphous germanium according to the twin crystal type (SiN) arrangement, and also include -V solar cells such as gallium arsenide (GnAs). Indium bismuth (Inp), indium gallium indium (InGaP), etc., π-VI such as cadmium telluride (CdTe), indium copper selenide (CuInSe2), etc., the basic structure of these solar cells are formed in the form of semiconductor The diode of the PN semiconductor generates light current by receiving light from one side, thereby generating electricity. In order to electrically discharge the electrodes at both ends thereof, it is necessary to form a layer of metal on the surface of the solar electric ground to form a conductive electrode. 〇General solar cells' back (non-illuminated surface) can be fully coated with a layer of metal, and the illuminating surface provides a large light-receiving area, and only electrodes can be formed by finger-printing multiple metal meshes. The finger-shaped metal part accounts for only about 5% of the total area to ensure power generation. These finger electrodes are easily broken or contacted by the bees to form a so-called internal series resistance Rs. The higher the series resistance Rs, the lower the output power of the solar cell, and the stability of the battery. The Electronic Technology Association (IEC) stipulates that 'each solar cell must measure the resistance of its internal series resistance to determine its quality. 5 200944820 Measure the internal tantalum resistance of such ΡΝ ϋ solar cells - can be divided into a iec stipulations (1 £ (: _ 891) direct measurement method, and indirect measurement method. Indirect measurement method is The positive ι-ν curve characteristic of the solar cell under non-lighting conditions extracts the parameter extraction including the internal series resistance value, such as the integral method (Ortiz Conde et al.) and the differential method (Werner). 】H proposed), Lee-style method (Lee. τ, C et al.), etc. The biggest disadvantage of these methods for extracting various parameters is that there are four parameters due to cross-correlation, and the series resistance is only one of them - and this The forward curve is non-linear, so that the four parameters are only dependent on the nonlinear relationship, and the calculated numerical accuracy is low, only about 5%~15%. The equivalent circuit of the general PN solar cell is shown in Figure 1. The Is constant current source represents the photocurrent of the solar cell after receiving light, the diode D represents the pn diode characteristic of the solar cell, Rsh represents the bypass resistance of the solar cell, and the leakage current is due to the manufacturing process. Rs represents the internal series resistance of the solar cell, which is the resistance to be measured in the present invention. According to IEC-89 1, the Rs of the solar cell must be provided with two different illumination intensity environmental quantities. The first illumination intensity is simulated sunlight intensity at AM1.5G. Currently, a solar simulator is used to provide about 1〇〇〇w/m2 light intensity to simulate sunlight. Under this illumination intensity, a variable load RL is used to change from open circuit (RL=〇〇) to short circuit (RL=〇), and the current I and voltage V′ between the two ends are measured to obtain a strong light intensity. 200944820 degrees RA! The next Ι-V curve. Typical] [_v curve is shown in curve L! of Figure 2] where ISC1 current represents short-circuit current (Isc) at the light intensity RAi (Voc Represents the open-circuit voltage ' Pmax is the maximum power of the battery. ❺

Subsequently, the same solar cell is irradiated with another small light intensity rA2 (for example, 500 W/m2), and the IV curve is also measured by sequentially changing the load R1 to obtain a curve L2 as shown in FIG. 2, which represents the light intensity RA2. The short-circuit current underneath, ν〇(:2 represents its open circuit. To measure the series resistance Rs, first take a point X' on the _v curve Li, the current IX, = ISC1-^ I, the corresponding terminal voltage For Vx, another point y is taken in the IV curve L2, the point current Iy,=IsC2_AI, and its corresponding voltage is Vy', then the internal series resistance v, -v, ώ y X S'lscrlsc2 (1) Comparing the other three parameters in the IV curve with each other 'only leaving the internal series resistance and directly calculating it, so it is called direct measurement method. Although its quasi-pain is extremely high, according to the current production line speed, about every 1 A solar cell can be produced in ~2 seconds. That is, the above solar simulator must provide two different light intensities in 1~2 seconds. The bulbs of the solar simulator are mainly based on the Ze lamp. 'The power is about 1000~2000 W, the temperature is extremely high, and therefore, often See the continuous power solar simulator can not provide two different stable power in such a short time. Another solar simulator is pulse type (pUlse), although it can be provided in 200944820 1~2 seconds Light intensity of two different powers, such as ★ and 500 w/m2, but its gas lamp must be ignited with high voltage (about 20,000V) every time to illuminate, and its life (life-time) The shape is shorter than the general fixed-power bulb, which not only causes the bulb to be replaced frequently, the maintenance materials are frequent, the maintenance cost increases, and the detection rate decreases. The price of W oil skyrockets, and the demand for solar energy (4) generational energy materials increases greatly. The product detection requirements are simultaneously improved, and how to provide a detection method with high detection efficiency, high accuracy, and low detection cost is a subject that the industry is eagerly awaiting. [Invention] Therefore, an object of the present invention is to provide an easy Solar cell internal series resistance measurement method implemented and conforming to IEC specifications. Another object of the present invention is to provide an optical source capable of extending the detection device. A solar cell internal series resistance measuring method for life. A further object of the present invention is to provide a solar cell internal series resistance measuring method with high measuring rate and improved product detection efficiency. Another object of the present invention is to provide The invention relates to a solar cell internal series resistance measuring system with rapid measurement. Thus, the present invention discloses a solar cell internal series resistance measuring method, wherein the tested solar cell has two end electrodes, and the method comprises the following steps: a) continuing Applying a bundle of simulated sunlight having a specific intensity to the solar cell under test; b) changing the resistance value of a variable load of one of the 8 200944820 solar cells in series, and measuring the corresponding terminal current of the solar cell at different resistance values And the terminal voltage value, and obtain the short-circuit current value isc when the load resistance value is zero; c) turn off the simulated sunlight 'select to apply a current to the tested solar cell, and measure the terminal voltage of the tested solar cell Vy; wherein, according to the corresponding terminal current and terminal voltage values, when the solar cell When the current value of the terminal is Isc-ΔΙ, the electrical waste value of the solar cell is ❹Vx, and d) the internal series resistance value (Vy_Vx)/Isc of the solar cell under test is calculated to be replaced by applying a reverse input current. The second illumination measurement, the invention can not only shorten the measurement time, accelerate the measurement efficiency; and because the light source illumination power is fixed', not only the accuracy of the measurement is easy to ensure, but also the service life of the light source is also prolonged, thereby further reducing maintenance and maintenance. The frequency of demand reduces the cost of measurement. [Embodiment] The foregoing and other technical features, features, and advantages of the present invention will be apparent from the following description of the preferred embodiments. The invention is improved by the specification of IEC-89 1, please refer to the measurement method of FIG. 3 and the circuit diagram of the measurement system of the 囷4 measurement system. First, the solar battery 1 is placed in step 31 as a The environment is shielded 40 to isolate external ambient light noise interference. And in step 32, the control device instructs to illuminate the light source 42 and apply a beam of simulated sunlight to the solar cell 1 to be tested. In this example, the 9 200944820 simulated sunlight is maintained at a specific intensity such as ami.5g. In the case of illumination, of course, as is familiar to those skilled in the art, it can be easily inferred that since the light source 42 for simulating sunlight is much higher than that of ordinary ambient light, even if there is no such mask in the measurement process, it is still acceptable. result. Subsequently, referring to Fig. 5, in step 33, the control unit 50 50 commands 'the resistance value of the variable load RL of the tandem solar cell 1 is gradually changed from an open circuit to a short circuit, and the galvanometer as a sensor Μ and the voltmeter 54 respectively measure the terminal current t and the terminal voltage v value corresponding to the respective resistance values and output to the control device 5 〇, thereby obtaining a curve as shown in the curve IV′ and obtaining a load resistance value of zero. Current value

Isc. Of course, as can be easily understood by those skilled in the art, the curve is here for easy understanding, and in actual operation, it is not necessary to take this picture. In step 34, the control device 5 is driven to turn off the simulated sunlight, so that the solar cell i under test is in an environment that is substantially free from light, and a current δι that is large enough to be easily determined is input from the power source 44. The electrodes at both ends of the solar cell 1 are measured by the voltmeter 54. At this time, the end of the solar cell 1 is charged, and is set to Vy, which is the dotted line in Fig. 6, L2, and the upper point y. It must be noted that since the actual metric only needs to measure the value of a single point y, L2 is only used for the description. Finally, in step 35, on the one hand, in the curve ^, the corresponding terminal current is taken as the point x, which defines the terminal power of the point as %. And the following formula (7) is calculated by the control device 5〇, and the internal series resistance value of the solar cell is obtained: 10 200944820

Isc (2) The principle of the formula (2) will be demonstrated below: the equivalent circuit of the PN type solar cell under illumination is as shown in Fig. 1 above, and the relationship between the terminal voltage V and the current I is

II 1 _Rsh q

In equation (3), 'IG is the reverse saturation current of the diode, and its size is about 10·8Α. 'q is the electron charge, α is an unknown variable, generally between 1 and 2, and Vd is the diode. The terminal voltage, u is the photocurrent, κ is the Boltzmann constant, and τ is the Kjeldahl temperature. At this point, the X point of the _v curve is taken as ix=isc· Δ I, and assuming that Δ 1 >> ls_lsc, the terminal voltage Vx at this time can be seen by the equation (3), which is ❹ ΔΙ-^01

Vx = -Rs (!Sc * ΔΙ) + L—3sh_+i q I. (4) When there is no light, Is = 〇, and the current input from the solar cell with a current value of Δ I is inward, the relationship between the voltage and the current Δ丨 is as shown.

Vy = RSAI +

ΚΤ ΚΤ L R L-

SH q + 1 (5) However, vD1 in equation (4) and ν〇2 in equation (5) must conform to equations (6) and (7) of 200944820,

ΔΙ-^L yDl=~M—, +1) q ι〇 .....(6)

ΔΙ-^ vD2=—^(—R

SH +1) q i〇 , (7) φ From (6) and (7), we can get v (4) minus (5), and get

Dl~VD2 ’ then Rs can be r£ y ψχ

Lsc (8) is obtained by subtracting the equations (4) and (5) from each other, and it can be seen that the other three unknown parameters a, I〇, RSH, and q are mutually phased, so that the present invention is V = 0 is a direct measurement. In a commonly used solar cell, the short-circuit current ISC is slightly smaller than the photocurrent Is, which can be obtained by the formula (3), and the short-circuit current Isc can be obtained by solving the following equation: 0 = -Rsisc+^n(_!!^ q l0 + 1) -.(9) If Rs=10mQ ' rsh =10〇〇Ω, v A * Isc=5A » a KT=25mV » d=0.6V, then h - he can be estimated from equation (9) = Vd/Rsh + e2I〇= V»Z = 0.6 x 10'3 ^

/ ^SH 12 200944820

Is therefore, if ΔI = 'J = 1A', then the above-mentioned hypothesis, Δ I > &Is; Is-Isc is established. In summary, the present invention uses the appropriate point X of the current ix=Isc_ai at one end of the solar cell IV curve obtained under one illumination, and ΔI is much larger than the difference between the photocurrent Is and the short-circuit current Isc. The corresponding terminal voltage is Vx; and in the absence of light, set the current of a current source to Δ I ' and input the solar cell to measure the corresponding terminal voltage to Vy ' The series resistance Rs = (Vy - Vx) / Isc is obtained. It can be seen that the series resistance is measured directly, and the other two unknown parameters a, I 〇 and R s can be eliminated by using the measurement process. Therefore, the accuracy of the present invention is as accurate as the method proposed by the : (: 891 specification); however, it is only necessary to utilize a single illumination process, which makes it possible to use the precise direct measurement of the constant power solar simulator. The solar light simulator can also prolong the life of the xenon bulb by more than one time due to less light irradiation, greatly reducing maintenance time and cost, and speeding up the measurement time. In the matte illumination step of the above embodiment, The current source Ic is supplied with a current of ΔΙ and input into the solar cell, and then the terminal voltage is measured. However, as shown in FIG. 7, the load, the power source, the galvanometer, and the voltmeter may be replaced by a single one to provide the same. Quadrant power supply (quadrant S〇Urce) QS 56 for positive and negative voltages and positive and negative currents, and measuring current and voltage values as a set of load, sensing and power supply 13 200944820 Device W with four quadrant power supply 56 Provide a current Δ〗 inward (hence the h on the coordinates of Figure 6) and measure the terminal voltage at this time

Vy' uses the π curve Li in the illumination step to obtain the point χ of the terminal current corresponding to Isc Δ I. When the terminal voltage at this point is Vx, the internal series resistance can be obtained by the equation (8).

❹ Using the four-quadrant power supply 56, you can directly change the applied voltage as a variable load during the illumination step. When controlling the four-quadrant power supply, the temperature of the solar cell is reduced to 纟, which can be simulated as The short-circuit state; and when the four-quadrant power source 56 is controlled so that the current across the solar cell under test is zero, the open state can be simulated, so that different states 其 'the end current and the terminal voltage value can be obtained, so that the light can be obtained. The _ν curve of the solar cell underneath. According to the above description, the present invention utilizes the reverse input current instead of the first illumination measurement, thereby shortening the measurement time and accelerating the measurement efficiency; and because the illumination power of the light source is fixed, not only the accuracy of the measurement is easily ensured, but also the service life of the light source is also Synchronous extension, which reduces the frequency of maintenance and demand, and reduces the cost of measurement, does all of the above objectives. The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All should remain within the scope of the invention patent. 14 200944820 [Simple diagram of the diagram] • Figure 1 is an equivalent circuit diagram of the Ganzhou-type solar cell; • Figure 2 is a schematic diagram of the internal resistance of the solar cell measured by the conventional direct measurement method; FIG. 4 is a block diagram showing the relationship between the processing device of the embodiment of FIG. 4 and the sensor, the power source, and the light source; FIG. 6 is a block diagram of FIG. A schematic diagram of a measurement curve; and FIG. 7 is a block diagram showing the relationship between a four-quadrant power source, a light source, and a control device in accordance with a second preferred embodiment of the present invention. 3 1-35...Step 42.. Light source 50...Control device 54.. voltmeter Is...Photocurrent I, △ I... Terminal current Rl..·Load resistance value Rs·.. Internal series resistance V, Vx, vy... terminal voltage [main component symbol description] 1... solar cell 40...mask

44...power supply 52... galvanometer 56... four-phase limited power supply (QS) D···diode isc!, ISC2, Isc... current value Li, L2, Lt', L2'... curve Rsh... Bypass resistors V〇c, V0C1, V〇C2...open circuit voltage 15

Claims (1)

200944820 X. Patent application scope: 1. A method for measuring the internal series resistance of a solar cell, wherein the solar cell to be tested has two electrodes at both ends, the method comprises the following steps: a) applying a simulated sun having a specific intensity Light to the solar cell under test; b) changing the state of the variable load of one of the tested solar cells in series between the short circuit state and the open state, and measuring the current and terminal voltage values of the solar cell in different states, And obtaining the short-circuit current value isc when the solar cell under test is short-circuited: c) turning off the simulated sunlight', selecting to apply a current to the tested solar cell, and measuring the terminal voltage Vy of the tested solar cell; Corresponding terminal current and terminal voltage value in the illumination step b), when the terminal current value of the solar cell is Isc_ Δ I, the terminal voltage value of the solar cell is Vx; and d) calculating the internal series connection of the tested solar cell Resistance value (Vy-VX) / ISC. 2. The method of claim 1, further comprising the step e) of placing the solar cell in a sheltered environment prior to applying the simulated sunlight step a). 3. A solar cell internal series resistance measuring system for detecting an internal series resistance of a tested solar cell, the tested solar cell having two electrodes, the system comprising: a group for illuminating the tested solar cell a light source: a series connected to the tested solar cell' and when the light source is irradiated to the 16 200944820 tested solar cell, 'changes its state between a short circuit state and an open state, detects the measured solar cell terminal voltage and terminal current, and Providing a load, sensing and power supply device for supplying current to the solar cell under test when the light source is not emitting light; and a set of controlling the light-emitting state of the light source and the state of the load, the sensing and the power supply device; for receiving from the load, Sensing and sensing values of the power supply device, obtaining a short-circuit current value Isc when the light source emits light and the load, sensing, and power supply device makes the measured solar cell terminal voltage value zero, and selecting a current value to obtain The solar terminal current value of the solar current is ISC_^I, the end electric grinding value Vx 'when the light source is not illuminated, the load, sensing and Current source means for supplying the △ I tested to the solar cell, and obtains the terminal voltage of the solar cell under test Vy; and calculating the internal tested solar cell series resistance (Vy_Vx) / Isc of the control means. 4. The system of claim 3, wherein the load, sensing, and power supply device comprises: a set of variable resistors connected in series with the tested solar cell; and a set of voltage and current sensors . 5. The system of claim 3, wherein the load, sensing, and power supply device comprises a set of four-quadrant power supplies. 6. The system of claim 3, 4 or 5 wherein the source is a set of constant power solar simulators. 7. The system of claim 3, 4 or 5, wherein the light source is a set of pulsed solar simulators 17 200944820. 8. The system of claim 3, 4 or 5, There is further included a set of shields for shielding the solar cell under test. 18