KR101824983B1 - Photovoltaic module, photovoltaic system and method for controlling the same - Google Patents

Abstract

The present invention relates to a solar module, a solar system and a method of operating the same. A method of operating a solar module according to an embodiment of the present invention includes: receiving a DC power from a solar cell module; calculating a maximum power point using the supplied DC power; Wherein the step of calculating the maximum power point comprises: if the ratio of the input current to the output current in the dc / dc converter is less than a predetermined value, , And calculating power for each cell according to a power-to-voltage curve for the solar cell module. Thus, it is possible to output the maximum power when a hot spot is generated.

Description

TECHNICAL FIELD The present invention relates to a photovoltaic module, a photovoltaic module, and a photovoltaic module,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic module, a photovoltaic system, and a method of operating the same, and more particularly, to a photovoltaic module, a photovoltaic system and a method of operating the same.

With the recent depletion of existing energy sources such as oil and coal, interest in alternative energy to replace them is increasing. Among them, solar cells are attracting attention as a next-generation battery that converts solar energy directly into electrical energy using semiconductor devices.

On the other hand, the photovoltaic module means that solar cells for solar power generation are connected in series or parallel, and the photovoltaic module can include a junction box for collecting the electricity produced by the solar cell.

An object of the present invention is to provide a solar module, a solar light system, and a method of operating the solar module, which can output maximum power when a hot spot is generated.

An object of the present invention is to provide a photovoltaic module, a solar photovoltaic system, and an operation method thereof, which is easy to install and is advantageous in expanding the capacity in the system configuration.

According to an aspect of the present invention, there is provided a method of operating a solar module, comprising: receiving a DC power from a solar cell module; calculating a maximum power point using the DC power; And outputting the corresponding power in correspondence with the calculated maximum power point, wherein the step of calculating the maximum power point includes the step of calculating the maximum power point when the ratio of the input current to the output current in the dc / dc converter is less than a predetermined value, To a set minimum voltage, and calculating power for each cell according to a power-to-voltage curve for the solar cell module.

According to another aspect of the present invention, there is provided a solar module including: a solar cell module having a plurality of solar cells; a dc / dc converter for level-converting and outputting a DC power supplied from the solar cell module; And a junction box including a control unit for calculating a maximum power point using the DC power supplied from the solar cell module and controlling the corresponding power to be output corresponding to the calculated maximum power point, When the ratio of the input current to the output current in the dc / dc converter is less than a predetermined value, the voltage in the power versus voltage curve of the solar cell module is shifted to the set minimum voltage, and the power is calculated for each voltage according to the power curve.

According to another aspect of the present invention, there is provided a solar photovoltaic system comprising: a plurality of solar cell modules; and a power source for converting the level of DC power supplied from each solar cell module Wherein the junction box includes a dc / dc converter for level-converting and outputting DC power supplied from each solar cell module, and a dc / dc converter for converting the input current ratio of the dc / , The voltage in the power-versus-voltage curve of the solar cell module is shifted to the set minimum voltage, the power is calculated for each voltage in accordance with the power-to-voltage curve, the maximum power point is calculated, And a control unit for controlling power to be outputted.

According to the embodiment of the present invention, when a hot spot occurs in one photovoltaic module, the voltage in the power versus power curve is shifted to the set minimum voltage, and the power is calculated for each voltage according to the voltage versus power curve , It is possible to simply calculate the maximum power point.

In particular, when the ratio of the input current to the output current in the dc / dc converter is less than the predetermined value, it is determined that the hot spot occurs, and the voltage in the voltage versus power curve is shifted to the set minimum voltage, The maximum power point can be easily calculated by calculating the power according to the voltage.

On the other hand, when hot spots do not occur, that is, when the ratio of the input current to the output current in the dc / dc converter is equal to or greater than a predetermined value, the power is calculated for each voltage in accordance with the voltage versus power curve, It is possible to simply calculate the maximum power point by determining it as the final maximum power.

Meanwhile, according to the photovoltaic system having the micro inverter according to the embodiment of the present invention, corresponding power can be outputted according to the calculated maximum power in each solar module.

Meanwhile, according to the solar power system having the power optimizer according to another embodiment of the present invention, corresponding power can be outputted according to the calculated maximum power in each solar module.

1 is a front view of a solar module according to an embodiment of the present invention.
Fig. 2 is a rear view of the solar module of Fig. 1;
3 is an exploded perspective view of the solar cell module of FIG.
4 is an example of a bypass diode configuration of the solar module of FIG.
Fig. 5 illustrates a voltage versus current curve of the solar module of Fig.
6 illustrates a voltage versus power curve of the solar module of FIG.
FIG. 7 illustrates an example of shadow generation in the solar module of FIG.
FIGS. 8A and 8B illustrate various examples of the power versus voltage curve at the time of shading of FIG.
9 is an example of an internal circuit diagram of a junction box of the solar module shown in Fig.
10 to 11B are diagrams referred to in the description of the operation of the circuit diagram of FIG.
12 is a flowchart showing an operation method of a solar module according to an embodiment of the present invention.
13 to 14 are diagrams referred to in explanation of the operation method of Fig.
15 is another example of the internal circuit diagram of the junction box of the solar module shown in Fig.
16 is an example of a configuration diagram of a solar photovoltaic system according to an embodiment of the present invention.
17 is another example of the constitution diagram of the solar photovoltaic system according to the embodiment of the present invention.
18A to 18B are diagrams for explaining power optimization of a solar photovoltaic system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The suffix "module" and " part "for components used in the following description are given merely for convenience of description, and do not give special significance or role in themselves. Accordingly, the terms "module" and "part" may be used interchangeably.

FIG. 1 is a front view of a solar module according to an embodiment of the present invention, FIG. 2 is a rear view of the solar module of FIG. 1, and FIG. 3 is an exploded perspective view of the solar module of FIG.

1 to 3, a solar module 50 according to an embodiment of the present invention includes a solar cell module 100 and a junction box 200 located on one side of the solar cell module 100 . The solar module 50 may further include a heat dissipating member (not shown) disposed between the solar cell module 100 and the junction box 200.

First, the solar cell module 100 may include a plurality of solar cells 130. The first sealing material 120 and the second sealing material 150 located on the lower surface and the upper surface of the plurality of solar cells 130 and the rear substrate 110 and the second sealing material 120 located on the lower surfaces of the first sealing material 120, And may further include a front substrate 160 positioned on the top surface of the sealing member 150.

First, the solar cell 130 is a semiconductor device that converts solar energy into electrical energy. The solar cell 130 includes a silicon solar cell, a compound semiconductor solar cell, A tandem solar cell, a dye-sensitized solar cell, or a CdTe or CIGS type solar cell.

The solar cell 130 is formed of a light receiving surface on which solar light is incident and a rear surface opposite to the light receiving surface. For example, the solar cell 130 includes a silicon substrate of a first conductivity type, a second conductivity type semiconductor layer formed on the silicon substrate and having a conductivity type opposite to that of the first conductivity type, An antireflection film formed on the second conductive type semiconductor layer and having at least one opening exposing a part of the surface of the second conductive type semiconductor layer; And a rear electrode formed on the rear surface of the silicon substrate.

Each solar cell 130 may be electrically connected in series, parallel, or series-parallel. Specifically, a plurality of solar cells 130 can be electrically connected by a ribbon 133. [ The ribbon 133 may be bonded to the front electrode formed on the light receiving surface of the solar cell 130 and the rear electrode collecting electrode formed on the rear surface of another adjacent solar cell 130. [

In the figure, it is illustrated that the ribbon 133 is formed in two lines, and the solar cell 130 is connected in series by the ribbon 133 to form the solar cell string 140. By this, six strings 140a, 140b, 140c, 140d, 140e and 140f are formed, and each string includes ten solar cells. Unlike the drawings, various modifications are possible.

On the other hand, each solar cell string can be electrically connected by a bus ribbon. 1 shows a first solar cell string 140a and a second solar cell string 140b respectively formed by bus ribbons 145a, 145c and 145e disposed under the solar cell module 100, The battery string 140c and the fourth solar cell string 140d illustrate that the fifth solar cell string 140e and the sixth solar cell string 140f are electrically connected. 1 shows the second solar cell string 140b and the third solar cell string 140c respectively by the bus ribbons 145b and 145d disposed on the top of the solar cell module 100, And that the battery string 140d and the fifth solar cell string 140e are electrically connected.

On the other hand, the ribbon connected to the first string, the bus ribbons 145b and 145d, and the ribbon connected to the fourth string are electrically connected to the first through fourth conductive lines 135a, 135b, 135c, and 135d, respectively The first to fourth conductive lines 135a to 135d are connected to the bypass diodes Da, Db, and Dc in the junction box 200 disposed on the back surface of the solar cell module 100. In the drawing, the first to fourth conductive lines 135a, 135b, 135c, and 135d extend to the back surface of the solar cell module 100 through the openings formed on the solar cell module 100. FIG.

It is preferable that the junction box 200 is disposed closer to the end of the solar cell module 100 where the conductive lines extend.

1 and 2, since the first to fourth conductive lines 135a, 135b, 135c, and 135d extend from the top of the solar cell module 100 to the back surface of the solar cell module 100, ) Is located at the upper part of the back surface of the solar cell module 100. FIG. Thereby, the length of the conductive line can be reduced, and the power loss can be reduced.

1 and 2, when the first to fourth conductive lines 135a, 135b, 135c, and 135d extend from the bottom of the solar cell module 100 to the back surface of the solar cell module 100, The solar cell module 200 may be positioned at the lower part of the back surface of the solar cell module 100.

The back substrate 110 may be, but is not limited to, a TPT (Tedlar / PET / Tedlar) type having a waterproof, insulating and ultraviolet shielding function as a back sheet. 3, the rear substrate 110 may be formed in various shapes such as a circular shape or a semicircular shape depending on the environment in which the solar cell module 100 is installed.

The first sealing member 120 may be attached to the rear substrate 110 to have the same size as the rear substrate 110 and a plurality of solar cells 130 may be formed on the first sealing member 120 And can be positioned adjacent to each other so as to achieve the same.

The second sealing member 150 may be positioned on the solar cell 130 and may be laminated to the first sealing member 120.

Here, the first sealant 120 and the second sealant 150 allow each element of the solar cell to chemically bond. The first sealing material 120 and the second sealing material 150 can be various examples such as an ethylene vinyl acetate (EVA) film.

On the other hand, the front substrate 160 is preferably placed on the second sealing material 150 so as to transmit sunlight, and is preferably made of tempered glass in order to protect the solar cell 130 from an external impact or the like. Further, it is more preferable to use a low-iron-content tempered glass containing a small amount of iron in order to prevent the reflection of sunlight and increase the transmittance of sunlight.

The junction box 200 is mounted on the back surface of the solar cell module 100 and can be power-converted using the DC power supplied from the solar cell module 100. Specifically, a capacitor unit (520 in FIG. 9) for storing DC power can be provided. Further, the junction box 200 may further include a dc / dc converter (530 of FIG. 9) for level-converting and outputting a DC power source. In addition, the junction box 200 may further include bypass diodes (Da, Db, Dc) that prevent the current between the solar cell strings from flowing backward. Further, it may further comprise an inverter (540 of FIG. 9) for converting the direct current power into the alternating current power. This will be described later with reference to FIG.

Thus, the junction box 200 according to the embodiment of the present invention includes at least the bypass diodes Da, Db, and Dc, a capacitor unit 520 for storing the DC power, a dc / (530 in Fig. 9).

When the junction box 200 is formed integrally with the solar cell module 100, the loss of the DC power generated in each solar cell module 100 is minimized as in the solar cell system shown in FIG. 16 or FIG. So that it can be efficiently managed. On the other hand, the junction box 200 integrally formed can be called a MIC (Module Integrated Converter) circuit.

On the other hand, in order to prevent moisture penetration of the circuit elements in the junction box 200, a coating for preventing moisture permeation may be performed using silicon or the like inside the junction box.

An opening (not shown) is formed in the junction box 200 so that the first to fourth conductive lines 135a, 135b, 135c and 135d are connected to the bypass diodes Da, Db and Dc in the junction box Can be connected.

On the other hand, during operation of the junction box 200, high heat is generated from the bypass diodes Da, Db, and Dc, and the generated heat is transmitted to the specific solar cell 130 Can be reduced.

In order to prevent this, the solar module 50 according to the embodiment of the present invention may further include a heat dissipating member (not shown) disposed between the solar cell module 100 and the junction box 200. In order to disperse the heat generated in the junction box 200, the cross sectional area of the heat dissipating member (not shown) is preferably larger than the cross sectional area of the plate (not shown). For example, on the entire rear surface of the solar cell module 100. The heat dissipating member (not shown) is preferably formed of a metal material such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), tungsten (W) or the like with good thermal conductivity.

On the other hand, an external connection terminal (not shown) for outputting a power-converted DC power or an AC power to the outside may be formed on one side of the junction box 160.

4 is an example of a bypass diode configuration of the solar module of FIG.

Referring to the drawings, bypass diodes Da, Db, and Dc may be connected corresponding to six solar cell strings 140a, 140b, 140c, 140d, 140e, and 140f. Specifically, the first bypass diode Da is connected between the first solar cell string and the first bus ribbon 145a, and is connected to the first solar cell string 140a or the second solar cell string 140b When the reverse voltage is generated, the first solar cell string 140a and the second solar cell string 140b are bypassed.

For example, when a voltage of approximately 0.6 V generated in a normal solar cell is generated, the potential of the cathode electrode is approximately 12 V (= 0.6 V * 20), as compared with the potential of the anode electrode of the first bypass diode Da Lt; / RTI > That is, the first bypass diode Da operates normally, not bypass.

On the other hand, when a hot spot occurs due to shading or foreign matter adhering to any solar cell of the first solar cell string 140a, the voltage generated in any one solar cell is approximately 0.6V (About -15 V), rather than a voltage of about < / RTI > Accordingly, the potential of the anode electrode of the first bypass diode Da becomes higher by about 15 V than that of the cathode electrode. Accordingly, the first bypass diode Da performs the bypass operation. Therefore, the voltage generated in the solar cell in the first solar cell string 140a and the second solar cell string 140b is not supplied to the junction box 200. [ In this way, when a reverse voltage generated in some solar cells is generated, it is possible to prevent destruction of the solar cell or the like by bypassing. In addition, except for the hotspot area, it is possible to supply the generated DC power.

Next, the second bypass diode Db is connected between the first bus ribbon 145a and the second bus ribbon 145b, and is connected to the third solar cell string 140c or the fourth solar cell string 140d When the reverse voltage is generated, the third solar cell string 140c and the fourth solar cell string 140d are bypassed.

Next, the third bypass diode Dc is connected between the first solar cell string and the first bus ribbon 145a, and is connected to the first solar cell string 140a or the second solar cell string 140b When the voltage is generated, the first solar cell string and the second solar cell string are bypassed.

4, unlike FIG. 4, six bypass diodes can be connected corresponding to six solar cell strings, and various other modifications are possible.

FIG. 5 illustrates a voltage vs. current curve of the solar module of FIG. 1, and FIG. 6 illustrates a voltage versus power curve of the solar module of FIG.

Referring to FIG. 5, as the open-circuit voltage Voc supplied from the solar cell module 100 increases, the short current supplied from the solar cell module 100 becomes smaller. According to the voltage-current curve L, the voltage Voc is stored in the capacitor unit 520 provided in the junction box 200.

Referring to FIG. 6, the maximum power Pmpp supplied from the solar cell module 100 may be calculated by a maximum power point tracking algorithm (MPPT). For example, while the open-circuit voltage Voc is decreased from the maximum voltage V1, power is calculated for each voltage, and it is determined whether the calculated power is the maximum power. Since the power increases from the voltage V1 to the voltage Vmpp, the calculated power is updated and stored. Then, the power decreases from the voltage Vmpp to the voltage V2, so that Pmpp corresponding to the voltage Vmpp is determined as the maximum power.

As described above, when hot spots do not occur, only one inflection point occurs in the voltage power curve L. Therefore, the maximum power can be easily calculated only by exploring the V2 section in the V1 section.

FIG. 7 illustrates an example of shadow generation in the solar module of FIG.

Referring to the drawing, a shadow is generated in the first solar cell stream 140a of the solar cell module 100 to generate a hot spot. As a result, the first bypass diode Da is turned on by the reverse voltage. Therefore, the DC power generated from the remaining strings 140c, 140d, 140e, and 140f except for the first and second solar cell strings of the solar cell module is output. For example, when a voltage of about 0.6 V is generated in one solar cell, a DC voltage of about 24 V is outputted.

On the other hand, when the two bypass diodes are turned on, a DC voltage of about 12 V is outputted.

FIGS. 8A and 8B illustrate various examples of the power versus voltage curve at the time of shading of FIG.

8A illustrates a case where one bypass diode among three bypass diodes Da.Db.Dc is turned on. As shown in the figure, when the hot spot occurs, the DC power supply level supplied from the solar cell module 100 is decreased, so that the first local maximum power point Lmpp1 corresponding to the first voltage VLmpp1, A second local maximum power point Lmpp2 corresponding to the second local maximum power point VLmpp2 may occur.

Next, FIG. 8B illustrates a case where two bypass diodes among three bypass diodes Da.Db.Dc are turned on. As shown in the figure, when the hot spot occurs, the DC power supply level supplied from the solar cell module 100 goes down, so that the third local maximum power point Lmpp3 or the fourth voltage Vmpp3 corresponding to the third voltage VLmpp3 The fourth local maximum power point Lmpp4 corresponding to the fourth local maximum power point Lmpp4 may be generated.

That is, in the case of a photovoltaic module in which a hot spot occurs, it may have a power-to-voltage curve as shown in FIG. 8A or 8B, which is different from the voltage-versus-power curve in FIG.

Fig. 9 is an example of an internal circuit diagram of the junction box of the solar module of Fig. 1, and Figs. 10 to 11B are drawings referred to the description of the operation method of Fig.

9, a junction box 200 according to an embodiment of the present invention includes a bypass diode unit 510, a capacitor unit 520, a dc / dc converter 530, an inverter 540, 550).

The junction box 200 outputs AC power. Since the junction box 200 is capable of AC power output, it can be called a junction box having a micro inverter.

The bypass diode section 510 is connected to the first to fourth conductive lines 135a, 135b, 135c and 135d arranged between the respective angles of the a-node, b-node, c- And third bypass diodes Da, Db, and Dc.

The capacitor unit 520 stores the DC power supplied from the solar cell module 100. Although three capacitors Ca, Cb and Cc are connected in parallel in the figure, they may be connected in series or in series-parallel combination.

 The dc / dc converter 530 performs level conversion using the DC power stored in the capacitor unit 520. In the figure, a buck converter using the turn-on timing of the switching element S1, the inductor L1 and the capacitor C1, and the diode D1 is illustrated.

On the other hand, the turn-on timing control of the switching element S1 may be performed by the control unit 550. [ The dc / dc converter 530 may be a flyback converter, a boost converter, a forward converter, or the like in addition to the buck converter shown in the drawing. (For example, a Cascaded Buck-Boost Converter).

The inverter 540 converts the level-converted DC power from the dc / dc converter 530 into AC power. In the drawing, a full-bridge inverter is illustrated. Namely, the upper and lower arm switching elements Sa and Sb connected in series to each other and the lower arm switching elements S'a and S'b are paired, and two pairs of upper and lower arm switching elements are connected in parallel to each other (Sa & Sb & S'b). Diodes are connected in anti-parallel to each switching element Sa, S'a, Sb, S'b.

The switching elements in the inverter 540 are turned on / off based on the inverter switching control signal from the inverter control unit (not shown). As a result, AC power having a predetermined frequency is output. Preferably, it has a frequency (approximately 60 Hz) equal to the alternating frequency of the grid.

Meanwhile, a capacitor unit (not shown) may be further provided between the dc / dc converter 530 and the inverter 540 to store the level-converted dc power. The capacitor unit (not shown) may include a plurality of capacitors, similar to the capacitor unit 520 described above.

As shown in Fig. 9, a capacitor section for storing DC power in the junction box, a dc / dc converter for level-converting and outputting the stored DC power, and an inverter for converting the level- It is possible to easily supply AC power through the junction box. In addition, it is easy to install the solar module, and it is advantageous to expand the capacity of the solar system including a plurality of solar modules and the system configuration.

The input current sensing unit A senses an input current ic1 input to the dc / dc converter 530. The input voltage sensing unit B receives the input current ic1 input to the dc / dc converter 530, And senses the voltage vc1. The sensed input current ic1 and the input voltage vc1 are input to the control unit 550. [

The output current sensing unit C senses the output current ic2 output from the dc / dc converter 530 and the output voltage sensing unit B outputs the output And senses the voltage vc2. The sensed output current ic2 and the output voltage vc2 are input to the control unit 550. [

On the other hand, the control unit 550 can output the converter control signal Ss1 for controlling the switching element of the dc / dc converter 530 in Fig.

On the other hand, the control unit 550 may output an inverter control signal for controlling the switching element of the inverter 540.

The control unit 550 controls the switching elements of the dc / dc converter 530 based on at least one of the sensed input current ic1, the input voltage vc1, the output current ic2 or the output voltage vc2 The turn-on timing signal Ss1 of the switch S1 can be outputted.

The control unit 550 can control the dc / dc converter 530 to calculate the maximum power point for the solar cell module 100 and accordingly output the DC power corresponding to the maximum power.

FIG. 10 is a graph showing a relationship between a first voltage power curve PV1 in the case where no hot spot is generated, a second voltage power curve PV2 in which a hot spot is generated in a single solar cell string due to shading, The third voltage power curve PV3 in which a hot spot is generated due to shading in the solar cell string of FIG.

The first voltage power curve PV1 corresponds to Fig. 6, the second voltage power curve PV2 corresponds to Fig. 8A, and the third voltage power curve PV3 corresponds to Fig. 8B.

For example, when no hot spot is generated, that is, when the input current ic1 input to the dc / dc converter 530 is equal to or greater than the reference value, the controller 550 sets the first voltage power curve PV1 as a base The dc / dc converter 530 can be controlled so as to calculate the maximum power point, and thereby output a DC power corresponding to the maximum power.

Specifically, the control unit 550 performs power calculation for the solar cell module 100 while varying the input voltage vc1 in accordance with the first voltage power curve PV1. Then, the controller 550 calculates the power for each input voltage vc1, compares the calculated power with the stored maximum power, and updates and stores the larger one as the maximum power. If the updated maximum power is the inflection point in the power versus voltage curve, the maximum power at the inflection point can be determined as the final maximum power.

As another example, when the hot spot occurs, that is, when the input current ic1 input to the dc / dc converter 530 is lower than the reference value, the control unit 550 outputs the second voltage power curve PV2 or the third voltage power Based on the curve PV3, the dc / dc converter 530 can be controlled to calculate the maximum power point and thereby output a DC power corresponding to the maximum power.

Specifically, the control unit 550 performs power calculation for the solar cell module 100 while varying the input voltage vc1 in accordance with the second voltage power curve PV2. In particular, as shown in FIG. 11A, the power calculation is performed while reducing the input voltage vc1 from the maximum voltage. Then, the controller 550 calculates the power for each input voltage vc1, compares the calculated power with the stored maximum power, and updates and stores the larger one as the maximum power. Then, it is determined whether or not the updated maximum power has reached the first maximum power value Lmpp1, which is the first inflection point. As shown in FIG. 11A, when the first maximum power value Lmpp1 corresponding to the first input voltage Vmpp1 is reached, since it corresponds to the inflection point of the second voltage power curve PV2, Can not be performed.

At this time, the controller 550 determines whether the ratio of the input current to the output current in the dc / dc converter 530 is less than a predetermined value. When the voltage is lower than the predetermined value, the voltage in the power curve PV2 with respect to the second voltage is shifted to the set minimum voltage Vx, and the power calculation is performed while varying the input voltage vc1 again. At this time, since the voltage sweep is performed at the lowest voltage Vx, the power calculation is performed while increasing the input voltage vc1 from the lowest voltage Vx.

Meanwhile, the predetermined value herein may be a criterion for determining whether a hot spot has occurred as the input current input to the dc / dc converter 530 decreases.

For example, when the dc / dc converter 530 is implemented as a buck converter, the input current ic1 becomes small when a hot spot is generated. However, the output current ic2 is the sum of the output current ic2 of the switching element s1 Depending on the switching operation, there may be no large variation.

That is, when a hot spot occurs, the ratio of the input current ic1 to the output current ic2 can be significantly reduced as compared with the case where hot spots do not occur. For example, when the solar radiation by the hot spot is reduced by 40%, the input current (ic1) ratio to the output current (ic2) can be lowered to about 60%.

In the embodiment of the present invention, when the solar radiation amount by the hot spot is reduced by 30% and the input current ic1 ratio to the output current ic2 is approximately 65% to 70%, the first maximum power detection algorithm is driven . That is, the voltage can be shifted to the lowest voltage.

On the other hand, the lowest voltage Vx may be approximately 5V.

Then, the controller 550 calculates the power for each input voltage vc1, compares the calculated power with the stored maximum power, and updates and stores the larger one as the maximum power. Then, it is determined whether or not the updated maximum power has reached the second maximum power value Lmpp2, which is the second inflection point. 11A, when it reaches the second maximum power value Lmpp2 corresponding to the second input voltage Vmpp2, since it corresponds to the inflection point of the second voltage power curve PV2, the maximum power point calculation is no longer performed Can not be performed.

Next, the control unit 550 compares the first maximum power value Lmpp1 calculated at the maximum power with the second maximum power value Lmpp2, and determines the maximum value as the final maximum power. Referring to FIG. 11A, the second maximum power value Lmpp2 may be determined as the final maximum power.

On the other hand, referring to FIG. 11B, the controller 550 can determine the final maximum power similarly to FIG. 11A.

11B, the power calculation is performed while reducing the input voltage vc1 from the maximum voltage to calculate the power for each input voltage vc1. The calculated power and the stored maximum power are compared with each other, And updates and stores the value as the maximum power. Then, it is determined whether or not the updated maximum power has reached the third maximum power value Lmpp3, which is the first inflection point. 11B, when the voltage reaches the third maximum power value Lmpp3 corresponding to the third input voltage Vmpp3, since it corresponds to the inflection point of the third voltage power curve PV3, the maximum power point calculation is no longer performed Can not be performed.

At this time, the controller 550 determines whether the ratio of the input current to the output current in the dc / dc converter 530 is less than a predetermined value. If the voltage is lower than the predetermined value, the voltage in the third power-voltage curve PV3 is shifted to the set minimum voltage Vx, and then the power voltage is varied while varying the input voltage vc1 again.

Then, the controller 550 calculates the power for each input voltage vc1, compares the calculated power with the stored maximum power, and updates and stores the larger one as the maximum power. Then, it is determined whether or not the updated maximum power has reached the fourth maximum power value Lmpp4, which is the second inflection point. 11B, when the voltage reaches the fourth maximum power value Lmpp4 corresponding to the fourth input voltage Vmpp4, since it corresponds to the inflection point of the third voltage power curve PV3, the maximum power point calculation is no longer performed Can not be performed.

Next, the control unit 550 compares the third maximum power value Lmpp3 calculated with the maximum power with the fourth maximum power value Lmpp4, and determines the maximum value as the final maximum power. Referring to FIG. 11B, the third maximum power value Lmpp3 may be determined as the final maximum power.

11A or 11B, the method of calculating the final maximum power may be referred to as a first maximum power point tracking algorithm (MPPT). The control unit 550 can apply this first maximum power detection algorithm when the current input to the dc / dc converter 530 is less than the reference value.

On the other hand, when the hot spot does not occur, that is, the method of calculating the final maximum power by the first voltage versus power curve PV1 of Fig. 10 is referred to as a second maximum power point tracking (MPPT) . The control unit 550 can apply the second maximum power detection algorithm when the current input to the dc / dc converter 530 is equal to or greater than the reference value.

11A, the control unit 550 determines whether or not the ratio of the input current ic1 to the output current ic2 is less than a predetermined value after detecting the maximum power at the first inflection point , And if applicable, move the voltage to the lowest voltage (Vx) in accordance with the first maximum power detection algorithm. Then, the maximum power at the second inflection point can be detected by performing power-to-voltage calculation. Then, by comparing the power at the first inflection point and the second inflection point, the maximum value can be determined as the final maximum power.

On the other hand, after detecting the maximum power at the first inflection point, the control unit 550 determines whether the ratio of the input current ic1 to the output current ic2 is less than a predetermined value, When the hot spot does not occur, the power at the first inflection point can be determined as the final maximum power. That is, a second maximum power detection algorithm can be used.

FIG. 12 is a flowchart showing an operation method of a solar module according to an embodiment of the present invention, and FIGS. 13 to 14 are drawings referred to the description of the operation method of FIG.

Referring to FIG. 12, the input current sensing unit A in the junction box 200 senses an input current ic1 supplied from the solar cell module 100 (S610). Then, the controller 550 determines whether the sensed input current ic1 is less than a reference value (S620). If it is less than the reference value, the control unit 550 calculates the maximum power according to the first maximum power detection algorithm (S630). On the other hand, when the sensed input current ic1 is equal to or greater than the reference value, the controller 550 calculates the maximum power according to the second maximum power detection algorithm (S640).

As described above with reference to Figs. 10 to 11B, when hot spots occur, that is, when the sensed input current ic1 is lower than the reference value, the controller 550 calculates the maximum power according to the first maximum power detection algorithm If the sensed input current ic1 is equal to or greater than the reference value, the controller 550 calculates the maximum power according to the second maximum power detection algorithm.

On the other hand, the control unit 550 controls the turn-on timing of the switching device S1 so that the dc / dc converter 530 outputs the corresponding DC power according to the calculated maximum power.

13 is a flowchart showing a first maximum power detection algorithm.

Referring to FIG. 5, the controller 550 calculates a power for each voltage according to a power versus power curve (S710). That is, as shown in FIG. 11A or FIG. 11B, the controller 550 calculates the power for each voltage based on the second voltage power curve PV2 or the third voltage power curve PV3. That is, the power calculation is performed while reducing the input voltage vc1 from the maximum voltage. Then, the control unit 550 calculates power by the input voltage vc1.

Next, the controller 550 compares the calculated power with the stored maximum power to update the maximum power (S715). The control unit 550 compares the calculated power with the stored maximum power, and updates and stores a larger one of them as the maximum power.

Next, the control unit 550 determines whether the updated maximum power is the second inflection point (S720). If not, it is determined whether the ratio of the input current to the output current of the dc / dc converter is less than a predetermined value (S725). If so, the voltage is shifted from the power curve to the set minimum voltage (S730). Then, step S710 and step S710 are repeated.

On the other hand, if the updated maximum power is the second inflection point, operation 740 is performed. That is, the control unit 550 compares the maximum power at the first inflection point with the maximum power at the second inflection point, and determines the maximum value as the final maximum power (S740).

As shown in FIG. 11A, when the first maximum power value Lmpp1 corresponding to the first input voltage Vmpp1 is reached, since it corresponds to the inflection point of the second voltage power curve PV2, Can not be performed. Accordingly, the control unit 550 sweeps the input voltage to the lowest voltage Vx and then performs the power calculation according to the voltage thereafter.

The control unit 550 calculates power for each input voltage vc1, compares the calculated power with the stored maximum power, and updates and stores a larger one of them as the maximum power. Then, it is determined whether or not the updated maximum power has reached the second maximum power value Lmpp2, which is the second inflection point.

11A, when it reaches the second maximum power value Lmpp2 corresponding to the second input voltage Vmpp2, since it corresponds to the second inflection point of the second voltage power curve PV2, Can not be performed.

Accordingly, the control unit 550 compares the first maximum power value Lmpp1 calculated at the maximum power with the second maximum power value Lmpp2, and determines the maximum value as the final maximum power. Referring to FIG. 11A, the second maximum power value Lmpp2 may be determined as the final maximum power.

According to the first maximum power detection algorithm, the maximum power of the solar cell module 100 can be accurately determined even when a hot spot occurs.

14 is a flowchart showing a second maximum power detection algorithm.

Referring to FIG. 5, the controller 550 calculates a power for each voltage according to a power versus power curve (S810). That is, the control unit 550 calculates the power for each voltage based on the first voltage power curve PV1 of FIG. 10A. That is, the power calculation is performed while reducing the input voltage vc1 from the maximum voltage. Then, the control unit 550 calculates power by the input voltage vc1.

Next, the control unit 550 compares the calculated power with the stored maximum power to update the maximum power (S815). The control unit 550 compares the calculated power with the stored maximum power, and updates and stores a larger one of them as the maximum power.

Next, the control unit 550 determines whether the updated maximum power is an inflection point (S820). If so, the maximum power at the inflection point is determined as the final maximum power (S840).

According to the second maximum power detection algorithm, when no hot spot occurs, only one inflection point occurs in the voltage power curve PV1, so that it is possible to simply determine the final maximum power using the inflection point.

15 is another example of the internal circuit diagram of the junction box of the solar module shown in Fig.

15, a junction box 200 according to an embodiment of the present invention includes a bypass diode unit 510, a capacitor unit 520, a dc / dc converter 530, and a control unit 550 . Unlike the internal circuit diagram of FIG. 9, the internal circuit diagram of FIG. 15 is characterized in that it does not include the inverter 540.

Accordingly, the junction box 200 can output DC power. In this case, when the junction box 200 performs a power optimizing function, the junction box 200 may be referred to as a power optimizer.

As shown in FIG. 15, the DC power supply can be easily supplied through the junction box by including the capacitor portion for storing the DC power in the junction box and the dc / dc converter for level-converting and storing the stored DC power. In addition, it is easy to install the solar module, and it is advantageous to expand the capacity of the solar system including a plurality of solar modules and the system configuration.

9 and FIG. 15, the junction box 200 may include only the bypass diode 510 and the capacitor 520. Accordingly, the dc / dc converter 530 and the inverter 540 may be separately disposed outside the junction box 200. [

On the other hand, as described above, the control unit 550 can change the maximum power detection algorithm depending on whether the input current ic1 is lower than the reference value, that is, whether hot spots are generated.

16 is an example of a configuration diagram of a solar photovoltaic system according to an embodiment of the present invention.

Referring to the drawings, the solar photovoltaic system of Fig. 16 includes a plurality of solar modules 50a, 50b, ..., 50n. Each solar module 50a, 50b, ..., 50n may include junction boxes 200a, 200b, ..., 200n for outputting AC power. The junction boxes 200a, 200b, ..., 200n may be referred to as junction boxes having microinverters. The alternating current power output from the junction boxes 200a, 200b, ..., as shown in FIG.

Meanwhile, the internal circuit of the junction box 200 of FIG. 9 according to the embodiment of the present invention can be applied to the microinverter of FIG.

On the other hand, for each of the solar modules 50a, 50b, ..., 50n in the solar photovoltaic system of Fig. 16, the first or second maximum power detection algorithm described in Figs. 10 to 14 can be applied.

17 is another example of the constitution diagram of the solar photovoltaic system according to the embodiment of the present invention.

Referring to the drawings, the solar photovoltaic system of Fig. 17 includes a plurality of solar modules 50a, 50b, ..., 50n. Each solar module 50a, 50b, ..., 50n may include junction boxes 1200a, 1200b, ..., 1200n for outputting DC power. In addition, a separate inverter 1210 for converting the DC power output from each of the solar module modules 50a, 50b, ..., 50n into AC power is further provided. At this time, the junction boxes 1200a, 1200b, ..., 1200n may be junction boxes having power optimizers for efficiently outputting DC power.

Meanwhile, the internal circuit of the junction box 200 of FIG. 15 according to the embodiment of the present invention can be applied to the power optimizer of FIG.

On the other hand, for each of the solar modules 50a, 50b, ..., 50n in the solar photovoltaic system of Fig. 17, the first or second maximum power detection algorithm described in Figs. 10 to 14 can be applied.

18A to 18B are diagrams for explaining power optimization of a solar photovoltaic system according to an embodiment of the present invention.

First, referring to FIG. 18A, a case where power optimizing is not applied will be described. In the case where a plurality of solar cell modules are connected in series as shown in the drawing, when hot spots are generated in some solar cell modules 1320 and some power loss occurs (for example, 70W power supply) A normal solar cell module 1310 also causes some power loss (for example, 70W power supply). Therefore, only 980W of power is supplied in total.

Next, referring to Fig. 18B, a case in which power optimization is applied will be described. When a hot spot occurs in some solar cell modules 1320 and some power loss occurs (for example, 70W power supply), the current supplied from the corresponding solar cell module 1320 is supplied to another solar cell module 1310, The voltage output from the solar cell module 1320 is lowered so as to be equal to the current supplied from the solar cell module 1320. [ Accordingly, in the solar cell module 1320 in which the hot spot has occurred, some power loss occurs (for example, 70W power supply), but in the normal solar cell module 1310, Power supply). Therefore, a total power of 1340 W can be supplied.

As described above, according to the power optimizing, the voltage supplied from the solar cell module in which the hot spot occurs can be adjusted in accordance with the current supplied from another solar cell module. To this end, each solar cell module receives a current value or a voltage value supplied from another solar cell module, and can control a voltage output in the solar cell module.

On the other hand, according to the embodiment of the present invention, the junction box 200 of FIG. 15 can be applied to the power optimizer of FIG. 18B.

It is to be understood that the invention is not to be limited in its application to the details of construction and the manner in which the above described embodiments of the invention are put into practice, .

Meanwhile, the method of operating the solar module of the present invention can be implemented as a code that can be read by a processor on a recording medium readable by the processor included in the solar module. The processor-readable recording medium includes all kinds of recording apparatuses in which data that can be read by the processor is stored. Examples of the recording medium that can be read by the processor include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may also be implemented in the form of a carrier wave such as transmission over the Internet . In addition, the processor-readable recording medium may be distributed over network-connected computer systems so that code readable by the processor in a distributed fashion can be stored and executed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention.

Claims (19)

Receiving DC power from a solar cell module;
Calculating a maximum power point using the supplied DC power; And
And outputting the corresponding power corresponding to the calculated maximum power point,
Calculating the maximum power point comprises:
moving the voltage in the power versus power curve to a set minimum voltage when the ratio of the input current to the output current in the dc / dc converter is less than a predetermined value; And
And calculating power for each voltage according to the power versus voltage curve for the solar cell module. The method according to claim 1,
Calculating the maximum power point comprises:
Comparing the calculated power with a stored maximum power to update the stored maximum power;
Determining a maximum value of the maximum power at the first inflection point and the maximum power at the second inflection point as the final maximum power when the updated maximum power is the second inflection point in the power versus voltage curve Wherein the solar module is a solar module. The method according to claim 1,
Calculating the maximum power point comprises:
Wherein when the input current ratio of the dc / dc converter to the output current is less than the predetermined value and the input current to the dc / dc converter is less than the reference value, the minimum voltage shifting step and the power calculating step are performed, 1 < / RTI > maximum power point in accordance with a maximum power detection algorithm. The method according to claim 1,
Calculating the maximum power point comprises:
Wherein when the input current ratio of the dc / dc converter to the output current is equal to or greater than the predetermined value and the input current to the dc / dc converter is equal to or greater than a reference value, And calculating the maximum power point. ≪ Desc / Clms Page number 21 > 5. The method of claim 4,
Wherein the second maximum power detection algorithm comprises:
Calculating power for each solar cell module in accordance with the voltage versus power curve;
Comparing the calculated power with a stored maximum power to update the stored maximum power; And
And determining the maximum power at the inflection point as the final maximum power when the updated maximum power is an inflection point in the power versus voltage curve. A solar cell module comprising a plurality of solar cells; And
A dc / dc converter for level-converting and outputting a DC power supplied from the solar cell module, and a dc / dc converter for calculating a maximum power point using the DC power supplied from the solar cell module, And a control section for controlling the output of the corresponding electric power,
Wherein,
Wherein when the ratio of the input current to the output current in the dc / dc converter is less than a predetermined value, the voltage in the power versus voltage curve of the solar cell module is shifted to a set minimum voltage, And the solar cell module. The method according to claim 6,
Wherein,
Comparing the maximum power stored at the first inflection point with the maximum power stored at the second inflection point when the updated maximum power is the second inflection point in the power versus voltage curve, And determines the maximum value of the maximum power at the inflection point as the final maximum power. The method according to claim 6,
Wherein,
Wherein when the ratio of the input current to the output current in the dc / dc converter is less than the predetermined value and the input current to the dc / dc converter is less than the reference value, And calculates the maximum power point according to the first maximum power detection algorithm, and calculates the maximum power point according to the first maximum power detection algorithm. The method according to claim 6,
Wherein,
Wherein when the input current ratio of the dc / dc converter to the output current is equal to or greater than the predetermined value and the input current to the dc / dc converter is equal to or greater than a reference value, And calculates the maximum power point. 10. The method of claim 9,
Wherein,
Calculates a power for each voltage according to the voltage-versus-power curve for the solar cell module according to the second maximum power detection algorithm, compares the calculated power with the stored maximum power, and updates the stored maximum power And determines the maximum power at the inflection point as the final maximum power when the updated maximum power is an inflection point in the power versus voltage curve. The method according to claim 6,
The junction box includes:
And a bypass diode for bypassing a solar cell generating a reverse voltage among the plurality of solar cells. The method according to claim 6,
The junction box includes:
And an inverter for converting the level-converted DC power from the dc / dc converter into AC power and outputting the AC power. 13. The method according to any one of claims 6, 11 and 12,
The junction box includes:
Wherein the solar cell module is integrated with the solar cell module. The method according to claim 6,
The dc / dc converter includes:
And a buck converter. A plurality of solar cell modules;
And a plurality of junction boxes corresponding to the respective solar cell modules for level-converting and outputting the DC power supplied from each of the solar cell modules,
Each of the junction boxes includes:
A dc / dc converter for level-converting and outputting DC power supplied from each of the solar cell modules; and a dc / dc converter for converting the input current ratio of the dc / A control unit for calculating a maximum power point by calculating a power for each voltage according to the power curve with respect to the voltage and outputting the corresponding power corresponding to the calculated maximum power point, Wherein the photovoltaic system comprises a photovoltaic cell. 16. The method of claim 15,
Wherein,
Comparing the maximum power stored at the first inflection point with the maximum power stored at the second inflection point when the updated maximum power is the second inflection point in the power versus voltage curve, And determines the maximum value of the maximum power at the inflection point as the final maximum power. 16. The method of claim 15,
Wherein,
Wherein the control unit calculates power for each voltage in accordance with the voltage versus power curve for the solar cell module when the input current input to the dc / dc converter is equal to or greater than a reference value, compares the calculated power with the stored maximum power, And determines the maximum power at the inflection point as the final maximum power when the updated maximum power is an inflection point in the power versus voltage curve. 16. The method of claim 15,
The junction box includes:
And an inverter for converting a DC power supply corresponding to the maximum power point into an AC power and outputting the AC power to the system. 16. The method of claim 15,
And an inverter for receiving DC power from each of the plurality of junction boxes, converting the DC power into an AC power, and outputting the AC power to the system.

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