JP2011249790A - Solar battery device - Google Patents

Abstract

A solar cell device having a simple configuration and excellent performance is provided.
A solar cell device (2) in which a plurality of solar cell elements (21, 22, 23) are electrically connected, wherein the bypass diode is electrically connected in parallel to one or more of the solar cell elements. D1, D2, D3, detours 31, 32, 33 that are electrically connected in parallel to the bypass diodes D1, D2, D3 to bypass the current, and switches that open and close the detour circuits 31, 32, 33 And a controller 4 that determines whether or not heat is generated from the bypass diodes D1, D2, and D3, and when it is determined that the heat is generated, the controller 4 closes the switch so that a current flows through the bypass. I have.
[Selection] Figure 1

Description

  The present invention relates to a solar cell device in which a plurality of solar cell elements are electrically connected.

  For example, when a solar cell element constituting the solar cell module is shaded on its light receiving surface and does not generate power, the electric resistance of the solar cell element increases, and heat is generated due to resistance loss. In order to avoid this, a bypass diode may be provided in the vicinity of the solar cell element so as to bypass the current so as not to flow into the shaded solar cell element.

  However, the bypass diode generates heat, and the heat may adversely affect the output characteristics of the solar cell element. For this reason, the heat generated from the bypass diode is radiated from the substrate or the terminal box provided with the bypass diode (see Patent Document 1 below).

JP 2006-49621 A

  However, the support of the solar cell element may be inferior in heat transfer, and it may be difficult to efficiently dissipate heat from the bypass diode. Further, when the terminal box is excellent in heat dissipation characteristics, the configuration becomes complicated.

  For this reason, there is a demand for an excellent solar cell device that sufficiently exhibits the function of the bypass diode while reducing the heat generation of the bypass diode with a simple configuration.

  Then, an object of this invention is to provide the solar cell apparatus provided with the outstanding performance by simple structure.

  A solar cell device according to the present invention is a solar cell device in which a plurality of solar cell elements are electrically connected, and a bypass diode electrically connected in parallel to one or more of the solar cell elements, When it is determined that there is heat generation by determining whether there is a bypass circuit that is electrically connected in parallel to the bypass diode and that bypasses the current, a switch that opens and closes the bypass circuit, and heat generation from the bypass diode. And a control unit that closes the switch so that a current flows through the bypass.

  According to the above solar cell device, it is possible to provide a solar cell device having an excellent performance of sufficiently exerting the function of the bypass diode while reducing the heat generation of the bypass diode with a simple configuration.

It is a circuit diagram which shows typically an example of the solar cell apparatus which concerns on this invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. (A)-(c) is a partial circuit diagram which shows typically the part of an example of the solar cell apparatus which concerns on this invention, respectively. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a partial circuit diagram showing typically a part of an example of a solar cell device concerning the present invention. It is a circuit diagram which shows typically an example of the solar cell apparatus which concerns on this invention.

  Hereinafter, an example of an embodiment of a solar cell device according to the present invention will be described with reference to the drawings.

<Basic configuration of solar cell device>
First, the basic configuration of the solar cell device of the present embodiment will be described. As shown in FIG. 1, the solar cell device 2 is configured by a plurality of solar cell elements being electrically connected, for example, a solar cell module or a solar cell array or the like in which the solar cell modules are electrically connected. . Hereinafter, a solar cell element string in which solar cell elements are electrically connected in series, parallel, or series-parallel is referred to as a solar cell element string. Note that one solar cell element is also included in the solar cell element string for convenience.

  The solar cell device 2 is opened and closed so as to bypass, for example, a bypass diode D1 and a current electrically connected in parallel to the bypass diode D1 that are electrically connected in parallel to one or more solar cell elements. The bypass contact 31 (a switch provided in the middle of the bypass route) to be determined and the presence or absence of heat generation of the bypass diode D1 are determined. And a control unit 4 configured to maintain the closed state. Here, the determination of the presence or absence of heat generation is not limited to confirming the fact that heat has been generated, but includes predicting in advance that heat will be generated in the future. Although a specific embodiment will be described later, for example, the heat generation amount is calculated from the voltage across the bypass diode D1 and the current flowing through the bypass diode D1, and the bypass contact is activated before the temperature increase of the bypass diode D1 is observed. It is also possible to use a method that does not directly measure the temperature, such as controlling the temperature. Further, by actually measuring the temperature of the bypass diode D1, predicting the time until the temperature reaches the predetermined temperature from the speed (time rate) of the temperature rise, and operating the bypass contact before the arrival time, the bypass diode D1 The temperature rise may be avoided.

  For example, the control unit 4 may include a temperature sensor that detects the surface temperature of the bypass diode D1 as described later in order to determine whether the bypass diode D1 generates heat or not, and detects a current flowing through the bypass diode D1. A current sensor may be provided, or a voltage sensor for detecting a voltage drop of the bypass diode D1 may be provided.

  In addition to the configuration described above, the solar cell device 2 may further include a cooling unit to be described later for cooling the bypass diode D1. This cooling means may be operated when the controller 4 determines that the bypass diode D1 generates heat. In this case, the cooling unit does not necessarily have to be operated by the control unit 4, and the cooling unit may be operated by an external power source.

<Constituent elements of solar cell device>
Next, the components of the solar cell device of this embodiment will be described.

  Each of the solar cell element strings 21, 22, and 23 constituting the solar cell device 2 shown in FIG. 1 is electrically and mechanically soldered to a plurality of solar cell elements by a conductive member such as a copper foil wire. Are connected in series. In designing the rated output, the solar cell device 2 determines an output voltage and an output current by connecting such a solar cell element string to an appropriate number.

  For example, assuming that the optimum operating voltage of a solar cell element of 156 mm square is about 0.5 V and the optimum operating current is about 7 A, the size of the solar cell module used in a general residential solar power generation device is about 1.3 m × In the case of 1 m, a total of 48 solar cell elements are required. In this case, six series of solar cell element strings in six series are made into 48 series (about 24V), or two series of solar cell element strings in 24 series are arranged in parallel to double the current (about 14A). it can.

  The bypass diodes D1, D2, and D3 are ideally arranged for each solar cell element, but in the present embodiment, the solar cell element strings 21 and 22 in which the solar cell elements are connected in about several to a dozen series. , 23, respectively. Further, silicon diodes, Schottky barrier diodes, thyristors, or the like are used as the bypass diodes D1, D2, and D3. Each bypass diode is electrically arranged in parallel on the positive electrode side and the negative electrode side of each solar cell element string. When a shadow or the like occurs in a certain solar cell element string and the internal resistance increases, the generated current of another solar cell element string connected in series to this solar cell element string is bypassed to the bypass diode. Thereby, it is avoided that the current is converted into heat by the internal resistance and power loss occurs. As for the electrical connection between the solar cell element string and the bypass diode, the positive electrode of the solar cell element string is connected to the anode side of the bypass diode, and the negative electrode side of the solar cell element is connected to the cathode side of the bypass diode.

  As the detour contacts 31, 32, 33, contact-type mechanical relays, semiconductor-type solid state relays, transistors or the like are suitable. In the contact type, a coil type relay having an a contact (conducting the contact when turned on) is suitable. Further, once the switch is turned on, power consumption can be reduced by using a ratchet relay that maintains the contact position. If the current is about 10 A, a small microrelay can be used, and the terminal box that houses the relay does not need to be enlarged. On the other hand, the semiconductor solid state uses a thyristor or a photocoupler and does not have a mechanical contact. In addition, a photocoupler for switching large currents such as an IGBT (Insulated Gate Bipolar Transistor) is also suitable, and the current can be handled only by a photocoupler up to about 2 A, thereby simplifying the circuit configuration. .

  The control unit 4 detects the surface temperature of the package case of the bypass diode, the voltage between the anode and the cathode, the input (or output) current, and the like, and determines whether a predetermined current or more is flowing through the bypass diode. Here, the “current greater than or equal to the predetermined value” refers to a current at which the temperature of the bypass diode, which has risen due to heat loss, causes a problem on the product. For example, the international standard IEC61215Ed2 of the solar cell module defines the upper limit of the temperature rise in the terminal box of the solar cell module, depending on the rating of the bypass diode, package size (or heat dissipation) and installation conditions, etc. Even if current flows through the diode and generates heat, the specified temperature must not be exceeded.

For example, as shown in FIG. 9, the control unit 4 includes a plurality of voltage dividing resistors 41, 42, 43, 44, an operational amplifier 45, a switching element 46, a coil 47, and the like, detects the voltage across the bypass diode D <b> 2, The voltage may be input to the comparison input terminal of the operational amplifier 45. With such a circuit configuration, when a reference voltage or higher is detected, a current is passed through the coil to keep the bypass contact 32 in a closed state.

  Generally, the factor that increases the temperature in the terminal box is the bypass diode. To prevent the temperature in the terminal box from increasing, do you reduce the heat generation by using an element with a small forward voltage drop of the bypass diode? Alternatively, the current that is a heat generation factor may be limited by how efficiently the heat from the bypass diode is radiated to the outside. In this embodiment, by providing a switch that electrically connects the anode and cathode of the bypass diode and a bypass, when a current exceeding a predetermined value flows through the bypass diode, a part of the current or Heat generation of the bypass diode that bypasses the whole can also be suppressed.

  In addition, since the control unit 4 performs the determination to operate the bypass contact, it is possible to identify which solar cell element string has a shadow or an output abnormality by the signal to operate the bypass contact, and the target It is possible to grasp the number of solar cell element strings to be several. In addition, the information grasped by this and the information processing equipment (PC, server device, etc.) provided on the receiving side is compared with information such as the time of occurrence of abnormalities, past power generation records, and solar radiation forecasts from weather forecasts, etc. Thus, from the actual power generation amount and the future power generation amount prediction, it is possible to obtain the loss of the generated power amount lost due to a shadow or output abnormality with high accuracy.

<Control of solar cell device>
Below, a specific example is demonstrated and demonstrated about the control of this embodiment. As shown in FIG. 1, the solar cell device 2 is composed of a string group in which three solar cell element strings 21, 22, and 23 are connected in series. The solar cell element string 21, the bypass diode D1, and the bypass contact 31, the solar cell element string 22, the bypass diode D2, and the bypass contact 32, and the solar cell element string 23, the bypass diode D3, and the bypass contact 33, The controller 4 is configured to open and close (ON-OFF) the electric circuit of the detour contacts 31, 32, 33 by electrically connecting them in parallel.

  For example, as shown in FIG. 2, when the solar cell element string 22 is shaded and a current flows through the bypass diode D2 and heat is generated in the bypass diode D2, this heat generation occurs. Is detected by the control unit 4. When the heat generation state exceeding a certain level is detected, the bypass contact 32 is kept closed by the control unit 4.

  As shown in FIG. 3A, for example, a temperature sensor such as a thermocouple constituting the control unit 4 may be brought into contact with the side surface of the bypass diode D2 to detect the temperature. At this time, if the power source of the control unit 4 is fed from the solar cell device 2, the power circuit and the feeding structure can be simplified and the power consumption can be reduced (the temperature rise of the bypass diode occurs during power generation). .

For example, if the solar cell element string 22 is shaded and the generated power is reduced, the internal resistance of the solar cell element string 22 is increased, so that the current naturally bypasses the bypass diode D2. At this time, since a voltage drop due to the semiconductor pn junction also occurs inside the bypass diode, a voltage of about 0.3 to 0.7 V remains, so that a part of the current may be generated depending on how the shadow is applied to the solar cell element string. In some cases, the battery element string may flow. In any case, since most of the current flows through the bypass diode, the power of the voltage drop of the bypass diode is thermally converted, and the temperature of the bypass diode rises. If the generated power of the solar cell device is small (the amount of solar radiation is not high), the bypass contact 22 does not operate because the temperature rise of the terminal box due to the heat generated by the bypass diode falls within the IEC standard, which is an international standard. When the amount of solar radiation further increases (weather conditions are good), if it is determined (calculated) that further temperature rise needs to be dealt with from the information of the sensor attached to the bypass diode D2, the control unit 4 makes a bypass contact 32. The bypass circuit having a smaller resistance value is constructed between the anode and the cathode of the bypass diode D2 by transmitting an operation signal to

  As a method for the control unit 4 to calculate the operating temperature, correlation data between the temperature rise of the bypass diode and the temperature rise of the terminal box is stored in advance in a storage unit (memory or the like) inside the control unit 4. The calculation method is based on the information, but it is not limited to this. The temperature sensor is arranged on the lid of the terminal box to control the temperature rise in the terminal box. May be.

  As described above, the generated current of the solar cell flows, for example, on the bypass contact 32 side, and for example, the temperature rise of the solar cell element string 22 and the bypass diode D2 can be suppressed.

  On the other hand, the generated voltage decreases by the amount of the solar cell element string 23. In such a case, when another solar cell device is electrically connected in parallel to the solar cell device 2, the solar cell element constituting the solar cell device 2 is maximum to compensate for the voltage drop. Since the output operating point is moved to reduce the generated current and increase the generated voltage to match the generated voltage of the solar cell device 2 with other solar cell devices, the current flowing through the bypass contact is also reduced. For this reason, the frequency at which the temperature of the bypass diode actually rises and the control unit 4 operates the bypass contact is small. For example, as shown in FIG. 2, even when the detour contact 32 is a mechanical contact such as a microswitch, it has a contact life of about 150,000 times. ) Can be used, and no intermediate maintenance or parts replacement is required. The operating power supply for the bypass contact may be obtained from the power generated by the solar cell device.

  The detour contact can be canceled by interlocking with the decrease in the power generated by the solar cell device (decreasing the amount of solar radiation due to sunset, etc.) and the power falling. As soon as these factors are removed, power generation can be resumed.

  When a current sensor is used for detecting the temperature rise of the bypass diode, the current sensor may be arranged on the current output side or the current input side of the bypass diode D2, as shown in FIG. As this current sensor, a sensor that is electrically arranged in series with a current line such as a shunt resistor or a loop coil sensor that detects the magnetic field strength generated in the electric wire can be applied. In general, since the amount of heat generated in the bypass diode increases as the flowing current increases, as described above, the bypass contact is operated by calculating whether or not the temperature has risen by the control unit 4.

  When a voltage sensor is used to detect whether or not the temperature has risen, a voltage signal between the anode and cathode of the bypass diode can be detected by the control unit 4 as shown in FIG. In general, the voltage drop of a diode increases as the forward current increases. Therefore, the voltage drop is converted into a current value and further converted into heat (temperature rise). Although the calculation content (control software) is more complicated than that of the current type, there is a great advantage in that the manufacturing process can be simplified because the sensor does not have to be arranged near the bypass diode. Further, if the control unit 4 has a voltage input terminal equipped with a microcomputer or the like, it may be directly input to the voltage terminal of the control unit 4 and the number of detection elements can be reduced.

As described above, the temperature of the bypass diode can be lowered by reducing a part of the current flowing through the bypass diode by bypassing it to another circuit. For the same reason, it is not necessary to cut the current of the other solar cell element strings flowing through the solar cell element string 100% (the purpose of the bypass diode arrangement is to avoid damage due to the occurrence of hot spots in the solar cell element). ) A design that takes into account the voltage drop value in the forward direction so that the current flows in a distributed manner in each of the solar cell element string, the bypass diode, and the bypass contact (for example, if the heat generation is such that the solar cell element does not fail) In order to prevent the diode or the bypass contact from operating, two bypass diodes are connected in series to increase the operation start voltage). Accordingly, it is possible to reduce the burden on the bypass diode and the bypass contact so that the element can be used for a long time, or to reduce the rated capacity to reduce the size.

  In the present embodiment, the control unit 4 and the detour contacts 31, 32, and 33 are separated from each other. However, the present invention is not limited to this, and each detour contact may be a self-supporting type having a determination circuit. Moreover, it is also possible to share the wiring of the solar cell element string without providing a dedicated signal line for transmitting a current or voltage signal to the control unit 4. As an example of the method, there is a method in which a bypass signal is pulse-controlled to switch between both ends of the solar cell element string and the diode, thereby generating a pulse signal (voltage) of transmission information and reading it by the control unit 4. . At this time, if the bypass circuits 31, 32 and 33 are not operated simultaneously, this reading can be simplified.

  Next, an example in which a semiconductor contact such as a solid state relay is used as a bypass contact will be described. The solid-state relay operates a semiconductor switch such as a photocoupler or a thyristor or relay having a larger power capacity with a photocoupler as a trigger, and any of the structures can be applied to the structure of this embodiment. In the present embodiment, description will be made using a photocoupler as a direct contact.

  As shown in FIG. 4, in the present embodiment, a photocoupler 35 is arranged in parallel with the bypass diode D2 as a bypass contact. The anode on the light emitting element side of the photocoupler 35 is electrically connected to the anode of the bypass diode D2, and the cathode side of the photocoupler 35 is electrically connected to the cathode of the bypass diode D2, respectively. The light receiving side (switch element) of the photocoupler 35 is The collector (drain) side is connected to the anode side of the bypass diode D2, and the emitter (source) is connected to the cathode side of the bypass diode D2.

  When the internal resistance of the solar cell element string 22 increases, a current flows through the bypass diode D2, and the voltage generated at both ends thereof (about 0.6V if the bypass diode is a silicon diode) causes the light emitting side of the photocoupler to be a light receiving side switch. Drive the element. Here, as the voltage drop of the bypass diode D2 (the amount of current flowing through the bypass diode) increases, more current flows to the switch element side, and the current flowing through the bypass diode D2 is bypassed.

  Here, if the rated value of the forward voltage drop of the switching element of the photocoupler 35 is smaller than the rated value of the diode D2, the current flows preferentially to the photocoupler 35 side, but no current flows to the bypass diode D2 ( When the voltage drop is lower than the operating voltage on the light emitting side of the photocoupler 35), the operation of the photocoupler 35 is stopped and current starts to flow again to the bypass diode D2. For this reason, it is preferable because the power generation return after the occurrence of shadows can be automatically performed quickly. In addition, the operation of the photocoupler 35 described above can be used as automatic control to serve as the control unit 4 and the number of parts can be reduced.

FIG. 5 drives the switch 37 having a larger current capacity by the photocoupler 35 shown in FIG. The switch 37 may be a semiconductor element or a mechanical contact, but when the switch 37 is operated, the voltage across the bypass diode D2, which is a trigger, becomes zero. For this reason, the operation of the switch 37 is also released. As a result, the photocoupler 3 is used to prevent chattering.
5 is provided with a delay circuit on the input side (light emitting side) or output side (switch element), a ratchet relay that mechanically maintains a contact position for the switch 37, or like a resistor 36 in the figure An element for generating a voltage may be disposed so that the operation of the photocoupler 35 is maintained.

  As shown in FIG. 6, the bypass diode D <b> 2 may be air-cooled by turning on and off the fan 38, which is a cooling unit, with the power flowing through the contact-side element of the photocoupler 35 using the bypass contact. When the current flows through the bypass diode D2 above a certain value, the photocoupler 35 is switched on by the voltage generated between the anode and cathode of the bypass diode D2, and the fan 38 rotates to stir the air around the bypass diode D2. To cool the bypass diode D2. The fan 38 can be sufficiently cooled even if it has a small wind force driven by a voltage comparable to the voltage generated at both ends of the bypass diode D2, but the agitated heat is only diffused in the terminal box. Therefore, it is advisable to design the housing at the same time so that the entire terminal box radiates heat to the outside air.

  As shown in FIG. 7, the driving power of the fan may be obtained from the outside. In this example, the operation of the photocoupler 35 causes the fan 38 to operate upon receiving power supply from the external power supply 39. For this reason, it is not necessary to match the voltage applied to the fan 38 with the voltage across the bypass diode D3. Moreover, it is possible to replace the element or device functioning as a cooling means other than the fan 38. For example, it is possible to use a Peltier element instead of a fan to forcibly cool the diode D3 and easily dissipate heat to the outside.

  As shown in FIG. 8, for example, a detour contact 40 may be newly provided between the solar cell element string 22 and the solar cell string 23 between the circuits of the solar cell element strings 22 and 23. For example, as shown in the drawing, a bypass contact 40 is provided between the input electric circuit of the solar cell element string 22 and the input electric circuit of the solar cell element string 23. In addition, although a detour contact is arrange | positioned also between other solar cell element strings, illustration is abbreviate | omitted. In this example, the detour contact 40 can be operated by the above-described device. However, a device that maintains the ON state as long as it does not receive a release signal (mainly current OFF), such as a ratchet type relay or thyristor, is used. It is good to have.

  When the solar cell element string 22 is shaded, a current flows through the bypass diode D2 to operate the photocoupler 35, a current flows through the coil 51 of the relay, and the bypass contact 40 is turned on. Since the detour contact 40 diverts the power from the solar cell element string 21 (not shown) to the input of the solar cell element string 23, no external current is applied to the solar cell element string 22, and almost no heat is generated. No (short-circuit current flows in the solar cell element string 22, so the temperature rise due to power generation occurs but is slight). This is because, in the solar cell element string 22 in a short-circuited state, even if an increase in internal resistance occurs in some of the solar cell elements, almost no voltage is generated, so the power is reduced and the amount of heat generated. This is because there are fewer. In addition, 52 in FIG. 8 performs the same operation as the coil 51, and is a relay coil that turns on a bypass contact (not shown). Reference numeral 53 in the figure denotes a photocoupler.

  According to the configuration of the present embodiment, if the solar cell element string 22 has sufficient power generation, the signal for operating the bypass contact 40 is maintained, and the solar cell element string 22 generates heat due to the input power from the solar cell element string 21. Therefore, it is not necessary to give a margin to the rated capacity of the bypass diode D2, and the size can be reduced.

Hereinafter, another implementation method (voltage or current method) for operating the bypass contact will be described. As shown in FIG. 10, the voltage across the bypass diode D2 may be directly measured by omitting a part of the voltage dividing circuit of the voltage detection circuit of FIG. With this circuit, the voltage dividing circuit on the reference voltage side can be shared by only one circuit for a plurality of solar cell element strings, so that the circuit configuration can be simplified by eliminating the voltage dividing circuit on each solar cell element string side. This is particularly suitable when there is little space for housing the voltage dividing circuit in the terminal box.

  Further, when the solar cell element string is shaded, the internal resistance of the solar cell element string is increased, so that the generated power generated by the other solar cell element strings flows to the bypass diode side. In the case where the bypass diode is a silicon diode, the voltage at both ends (between the anode and the cathode) is about 0.6 V, so that the reference voltage (the voltage dividing circuit on the reference voltage side described above) In comparison, it is determined that the voltage is for operating the bypass contact, and the control unit 4 sends an operation signal to the bypass contact to operate the bypass contact. In this example, once the bypass contact is operated, the state is continued for a certain time (for example, 1 hour), the bypass contact is opened again, the voltage across the bypass diode D2 is measured, and the bypass contact is operated again. Alternatively, it can be determined by the control unit 4 that it is determined that the shadow has recovered and control is not performed.

  Further, by using a thyristor instead of the bypass diode, the bypass contact and the circuit for maintaining the contact operation can be used together, and the number of parts can be greatly reduced. Specifically, for example, as shown in FIG. 11, a shadow or the like is generated in the solar cell element string 23, and a current limiting resistor 49 and a bypass detection diode Ds connected in parallel to the solar cell string 23 are provided. In the electric circuit, when a current flows to the bypass detection diode Ds side, the current flowing through the current limiting resistor 49 starts from point E, which is a connection point between the current limiting resistor 49 and the bypass detection diode Ds. The thyristor 48 is operated by flowing into the gate input of the thyristor 48 connected to the electric circuit. Since the thyristor 48 allows a current to flow in the same manner as the bypass diode, a large current does not flow through the current limiting resistor 49 and the bypass detection diode Ds. Since the current limiting resistor 49 and the bypass detection diode Ds need only use small-capacity elements of several tens to several hundreds of mA, the number of parts is small and the element size is small, so there is room in the space in the terminal box. It is suitable when there is not. Once the thyristor 48 is operated, the energized state is maintained until the current including the generated current of the solar cell element string and other current flowing into the thyristor 48 disappears (for example, the power generation is stopped due to sunset). Therefore, the circuit configuration can be simplified.

  In addition, the operation of the detour contact may be appropriately activated / stopped in accordance with the occurrence / resolution of a shadow or the like. Specifically, for example, a circuit configuration as shown in FIG. When a current flows through the bypass diode D2, a magnetic force is generated in the coil 50 connected in series with the bypass diode D2 and the switch 37 is turned on. However, since the current is limited by the resistor 36, a part of the current also flows on the coil side. Therefore, if the shadow on the solar cell element string 22 or the output abnormality is not resolved, the current bypass to the bypass contact side may be continued. As a result, when the shadow or the like is eliminated and a current flows on the solar cell element string 22 side, the current does not flow to the coil 50, and the contact of the switch 37 by the magnetism of the coil 50 is opened. it can.

  In the above example, the determination is made by looking only at the voltage of the bypass diode D2. However, the present invention is not limited to this. A method for comparing the operation determination elements of a plurality of bypass contacts, a plurality of different elements (voltage measurement, temperature measurement, and It may be determined with higher accuracy and without erroneous determination by combining current measurement and the like.

For example, if a comparison is made with the voltages of other bypass diodes D1 and D3 in addition to the voltage of the bypass diode D2, the difference in solar radiation (whether there is a shadow) can be clearly determined. . For example, the same effect can be obtained by measuring the current flowing through the bypass diode D2 and the voltage between both ends. Further, for example, even in the method of measuring the temperature of the bypass diode D2, if the temperature difference with the other bypass diodes D1 and D3 is compared, even if there is an external factor that induces a temperature increase of the bypass diode, If the relative value of the temperature of the bypass diode is used as a reference value for determination, control without erroneous determination can be performed.

  Furthermore, when the determination of operating the bypass contact can be performed as described above, if the operation signal of the bypass contact can be output from the control unit 4 to the outside, what is the power generation voltage of the solar cell element string? You can see if it falls. Using this information, in the power conditioner MPPT (Maximum Power Point Tracking) control (maximum power point tracking control), a plurality of maximum power points generated when solar cell element strings having different output voltages are connected in parallel ( It is possible to predict and calculate what is the optimum maximum power point (how many volts) for a plurality of peak voltage points in the generated power curve).

  Specifically, for example, when a control for selecting a maximum power point called general hill-climbing control is used, the MPPT control of the power conditioner is set to the maximum power point of the power curve on the side where the amount of power is low for some reason. Even if the control (operating voltage point) is selected by mistake, in order to determine whether or not the maximum power point is optimal, it is necessary to perform control such as checking the power curve over the entire area. During the confirmation operation, power loss (power lost due to not being the maximum power point) occurred. According to this embodiment, when a part of the solar cell element string is bypassed by the bypass contact, the generated voltage decreases, but what percentage of the generated voltage by the remaining solar cell element string is normal (loss rate) ), It is possible to accurately grasp the number of volts where the second maximum power point is generated when the power is combined with the generated power of other normal solar cell strings connected in parallel. Can be calculated. Therefore, since it is known that the point is not optimal, it is only necessary to automatically select the other maximum power point side, and it is possible to perform control with minimum power loss due to MPPT control.

  Next, a method of calculating the loss amount of generated power based on the determination result of operating the bypass contact will be described. The same effect can be obtained when a plurality of solar cell modules are used to form a solar cell module string, and a solar cell array in which a plurality of the solar cell module strings are connected in series. For example, the solar cell modules in FIG. 11 may be electrically connected in series and in parallel to form a solar cell array.

  Moreover, in such a solar cell array, it sends to the comprehensive control apparatus (for example, power conditioner) which receives the signal which operates the bypass contact from the control part of each solar cell module, and generated electric power is sent by operation | movement of a bypass contact. If you can add (multiply) how many solar cell element strings (possible in either solar cell element unit or solar cell module unit) are lost, what percentage of the power loss due to shadows etc. has reached? The loss rate can be calculated, and the information can be notified to the user or the maintenance company using a display device or a communication network such as the Internet.

  In addition, it is difficult to determine whether the decrease in generated power is due to factors such as shadows, and special equipment such as measurement of solar radiation intensity is required, whereas the number of solar cell element strings that do not generate power due to the effects of shadows, etc. Therefore, if the total amount of power generation at that time is known, the amount of power loss can be accurately calculated from the ratio. Therefore, it is possible to calculate the amount of power loss regardless of fluctuations in solar radiation intensity, accurately calculate the daily, monthly and yearly power loss and accept the effects of shadows, etc., or make investments such as relocation Can also provide important information to the user's judgment.

FIG. 13 is a circuit diagram and arrangement showing an example in which the circuit of FIG. 1 is applied to a solar cell module.
The solar cell device 2 has a solar cell element provided on a glass or resin translucent substrate. In addition, in this example, since a general solar cell module is used, description is abbreviate | omitted about a detailed structure, However, It is set as a thin film type solar cell or a crystalline solar cell. Even if these solar cells are different in manufacturing method and structure, they all have an output terminal (output +, output-in the figure) for taking out generated power on the non-light-receiving surface side.

  The output terminal is housed in a resin or metal terminal box 60 from the viewpoint of safety and waterproofness. The terminal box 60 is a protective layer (thin film type) on the non-light-receiving surface of the solar cell module or a back sheet (crystal type) ) With an adhesive or the like. Inside the terminal box 60, in addition to the output terminals, terminal portions (A, B, C, D in the drawing) electrically drawn out in parallel from the series connection portions of the solar cell element strings 21, 22, 23. By using these terminal portions (A, B, C, D), the bypass diodes D1, D2, D3 are electrically connected so as to be parallel to the solar cell element strings 21, 22, 23, respectively. Has been. Further, bypass contacts 31, 32, and 33 are provided in parallel with each of the bypass diodes D1, D2, and D3.

  Thus, by arranging each output terminal, each terminal unit, each bypass diode, and each bypass contact in the terminal box 60, information such as voltage and current required for the control unit 4 to make a determination to activate the bypass contact, While facilitating the collection of information such as the amount of heat of the bypass diode, it is possible to reduce the number of members by shortening the length of the wiring of the sensor necessary for collecting information of each part and the length of the command signal wiring to the bypass contact.

2: Solar cell device 31, 32, 33, 40: Detour contact 4: Controllers 21, 22, 23: Solar cell element string 35: Photocoupler 36: Resistor 37: Switch 38: Fan 39: External power supply D1, D2 , D3: Bypass diode

Claims (6)

A solar cell device in which a plurality of solar cell elements are electrically connected,
A bypass diode electrically connected in parallel to the one or more solar cell elements;
A detour that is electrically connected in parallel to the bypass diode and bypasses the current;
A switch for opening and closing the bypass,
A controller configured to determine whether heat is generated from the bypass diode and to close the switch so that a current flows through the bypass when it is determined that the heat is generated. Solar cell device.   The solar cell device according to claim 1, wherein the control unit includes a temperature sensor that detects a temperature of the bypass diode.   The solar cell device according to claim 1, wherein the control unit includes a current sensor that detects a current flowing through the bypass diode.   The solar cell device according to claim 1, wherein the control unit includes a voltage sensor that detects a voltage drop in the bypass diode.   The solar cell device according to any one of claims 1 to 4, further comprising cooling means for cooling the bypass diode.   The solar cell device according to claim 5, wherein the cooling unit operates when it is determined by the control unit that the bypass diode generates heat.

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