JP2003092418A - Solar cell panel and connection direction switching control method of solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure to realize a low cost and effectively recover the generated power at insolated portions to avoid reducing an output voltage even when it is partly shaded. SOLUTION: The panel has a plurality of parallel connected units composed of a plurality of series connected solar cell modules 3 wherein the modules 3 in adjacent units 4 are interconnected to allow the connecting direction to be switched. The modules 3 in the unit 4 are connected in series through diodes 2, switching means 8 are provided between positive electrodes 3a in one of modules 3 adjacent in the unit arranging direction and negative electrodes 3b in the other module 3, and secondary cells 9A, 9B, 9C and 9D for keeping a previous voltage before switching of the connecting direction of the modules 3 are attached to the negative electrodes 3b of the modules 3 in the unit 4A at one end and the positive electrodes 3a of the modules 3 in the unit 4C at the other end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell panel suitable for use in moving bodies such as automobiles and ships.

[0002]

Conventionally, when a solar cell panel formed by connecting a plurality of units in which a plurality of solar cell modules are connected in series is connected in parallel, for example, when mounted on an automobile, To avoid a drop in output voltage when the battery panel is partially shaded,
By using the two-point switching means (actually, an electromagnetic relay), the solar cell modules of adjacent units are connected to each other, that is, the solar cell modules that can secure sunlight are formed into a unit to obtain a required output voltage. In this case, the electromagnetic relay itself is not suitable for installation in the solar cell panel because it is difficult to make it thin, and power is consumed for switching, so the solar cell panel is partially shaded and free. Even in situations where the amount of power generation is decreasing,
There is a problem that the use of the electromagnetic relay is extremely unfavorable.

Further, when switching means such as a voltage driving type semiconductor switching element which consumes almost no power is used as the switching means, two switching means for one solar cell module and a voltage signal line for operating them are provided. At this time, if the solar cell module is downsized and the number of solar cell modules in one unit and the number of the solar cell modules are increased due to the design convenience such as providing a gentle curvature to the solar cell panel, There is a problem that the number of constituent elements of the battery panel increases dramatically and the cost increases, and it has been a conventional problem to solve these problems.

[0004]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above-mentioned conventional problems. The structure is simplified and the cost is reduced. Even if it gets into the shade, it is possible to effectively recover the generated power of the part where there is sunshine and avoid the decrease of the output voltage. It is intended to be provided.

[0005]

According to a first aspect of the present invention, a plurality of solar cell modules are connected in series and a plurality of units are connected in parallel. In a solar cell panel in which solar cell modules are connected to each other and the connection direction of the solar cell modules can be switched, a plurality of solar cell modules in a unit are connected in series via a diode and the solar cells adjacent to each other in the unit arrangement direction are connected. A voltage-driven opening / closing means is provided between the positive electrode of one solar cell module of one of the battery modules and the negative electrode of the other solar cell module, and in the unit located on one end side of the plurality of units arranged in parallel. For each negative electrode of the solar cell module and each positive electrode of the solar cell module in the unit located on the other end side, The voltage holding means for maintaining the switch before the voltage at the stage of switching the connection direction of the module has a structure in which respectively, are the means for solving the conventional problems described above the structure of the solar cell panel.

Further, the solar cell panel according to the present invention is
According to a second aspect, the voltage holding means is a secondary battery that is charged by the generated current of the solar cell module.

Further, in the solar cell panel according to the present invention, as in claim 3, the secondary battery has a charging capacity capable of continuously discharging the generated current of the solar cell module for 1 hour or more, and The charging characteristic is such that 20% or more of the charging capacity can be charged by the generated current, and claim 4 has an output voltage detecting means and an output current detecting means.

On the other hand, the solar cell module connection direction switching control method according to a fifth aspect of the present invention is the solar cell panel according to the fourth aspect, wherein one solar cell in the solar cell modules in all units is When the battery module comes into the shadow, the connection direction of the solar cell module is switched based on a decrease in both the output voltage and the output current detected by the output voltage detection means and the output current detection means. The configuration of the connection direction switching control method of the module is used as means for solving the above-mentioned conventional problems.

[0009]

The solar cell panel according to claim 1 of the present invention has the above-described structure. Therefore, for example, when the solar cell panel is mounted on an automobile, it opens and closes when it is partially shaded. By connecting the solar cell modules of the units adjacent to each other by means to avoid a decrease in the output voltage, a current is generated by the diode and the voltage holding means with respect to the solar cell modules in the units that were connected until then. Since it is cut off, it is not necessary to provide an opening / closing means for separating the solar cell modules in the unit, and the number of the opening / closing means and the drive wiring are reduced by half accordingly.

Since the solar cell panel according to claim 2 of the present invention has the above-mentioned structure, when the solar cell modules of the units adjacent to each other are connected to each other, the potentials of the solar cell modules located at both ends are self-adjusted. Since the generated power can be supplied, the solar cell panel according to claim 3 of the present invention has the above-described configuration, so that deterioration can be suppressed and the life of the secondary battery can be extended.

In the inventions according to claims 4 and 5, the above-mentioned configuration is adopted. Therefore, when the solar cell panel is partially shaded, the connection direction of the solar cell modules is automatically changed to the unit arrangement direction. Will be switched to.

[0012]

Since the solar cell panel according to claim 1 of the present invention has the above-mentioned structure, the number of opening / closing means and the driving wiring can be reduced to half compared with the conventional one. While realizing the simplification of the structure and cost reduction, for example, when it is mounted on a car, it is possible to prevent the output voltage from decreasing even if it is partially shaded. Excellent effect is brought about.

Further, in the solar cell panel according to the second aspect of the present invention, in addition to the same effect as the invention according to the first aspect, the solar cell modules of adjacent units are connected to each other. That is, the potentials of the solar cell modules located at both ends can be covered by self-generated power, and the solar cell panel according to claim 3 of the present invention can realize a long life of the secondary battery. Very good effect.

According to the invention described in claim 4 and claim 5, since the above-mentioned constitution is adopted, even if the solar cell panel is partially shaded, the connection direction of the solar cell modules is automatically changed to the unit arrangement direction. It is possible to prevent the decrease of the output voltage by switching to the above.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the solar cell panel according to the present invention. In this embodiment, the solar cell panel according to the present invention is mounted on an automobile and used.

As shown in FIG. 1, this solar cell panel 1
Is the three solar cell modules 3 through the diode 2.
Is formed by connecting in parallel three units 4 each of which is connected in series. A voltage detecting means 5 is provided between both output terminals 1a and 1b, and the voltage detecting means 5 and the positive electrode side. A current detecting means 6 and an output opening / closing means 7 are provided between the output terminal 1a and the output terminal 1a.

In this solar cell panel 1, three units 4 are arranged so as to be parallel to each other, and each solar cell module 3 is arranged in a matrix so that the solar cells adjacent to each other in the unit arrangement direction are adjacent to each other. The voltage-driven opening / closing means 8 is provided between the positive electrode 3a of one solar cell module 3 of the battery modules 3 and the negative electrode 3b of the other solar cell module 3 to connect the solar cell modules 3 in the column direction. By making it possible to switch from the row direction to the row direction, when a part of the unit 4 enters the shadow when the vehicle is stopped, the solar cell modules 3 of the units 4 adjacent to each other are connected, that is, the sunshine The obtained solar cell modules 3 are connected to each other to secure the output voltage.

In this case, three units 4 arranged in parallel
Between the negative electrode 3b and the negative electrode side output terminal 1b of the solar cell module 3 in the unit 4A located on one end side of the secondary battery 9A, 9B having a small capacity as a voltage holding means.
The reverse current prevention diode 2A and the opening / closing means 10 are provided in parallel between the secondary batteries 9A and 9B and the negative output terminal 1b.

The secondary batteries 9A and 9B are adapted to be charged by turning on the opening / closing means 10 while the solar cell modules 3 are connected in series in the unit 4 to generate electricity. The charging current during this period is 4
It is below the power generation current flowing inside (power generation current per solar cell module).

The secondary batteries 9A and 9B are
Each solar cell module 3 connected while switching the connection direction of the solar cell module 3 and connecting the solar cell modules 3 of the units 4 adjacent to each other to generate electric power
The potential of the negative electrode 3b is maintained at the potential before switching (potential when the solar cell modules 3 are connected in series in the unit 4 to generate power).

At this time, the secondary batteries 9A and 9B are in a discharged state, and each discharges a current equivalent to the power generation current of the connected solar cell module 3. If this charging / discharging current is large compared to the nominal capacity of the secondary battery, heat generation of the secondary battery and voltage fluctuation during charging / discharging will be large, and the deterioration of the secondary battery will be accelerated, and the performance as a solar cell panel will increase. Therefore, it is desirable that the nominal capacity of the secondary battery be such that the short-circuit current (corresponding to the maximum output current) of the solar cell module 3 can be discharged for 1 hour or more. In order to suppress the voltage fluctuations, it is more preferable that the size is such that discharge can be performed for 5 hours or more.

Further, as described above, the solar cell module 3
The stop time of a vehicle whose connection direction is switched from the column direction to the row direction is 1 to 2 when waiting for a signal or waiting for a crossing.
It is about a minute, and the secondary battery can operate if the charged amount is 20% or more.

In this solar cell panel 1, the operating current and voltage are controlled so that the amount of power generation is maximized by the maximum output operating point tracking means connected to the outside as will be described later. The solar cell panel 1 is operated in the unconnected state beforehand, and the maximum current flowing through the unit 4 and the operating voltage at the connection point of the secondary battery are measured during the daytime (in the secondary batteries 9A and 9B of FIG. 1, V1 and V2 are measured). ), When the charging characteristics of the secondary battery are measured at this maximum current, the type and the number of series of the secondary batteries 9A and 9B are set so that the voltage of the secondary battery reaches the operating voltage at 20% or more of the charge amount. It is desirable to select the output characteristics of the solar cell module 3 to be combined.

Furthermore, in order to cope with a case where the vehicle is stopped for several tens of minutes, such as during a traffic jam, the types of the secondary batteries 9A and 9B and the type of the secondary batteries 9A and 9B are set so that the operating voltage is reached when the charge amount is 50% or more. It is desirable to select the number of series and the output characteristics of the solar cell module 3 to be combined.

On the other hand, between the positive electrode 3a and the positive electrode side output terminal 1a of the solar cell module 3 in the unit 4C located on the other end side of the three units 4 arranged in parallel,
Small-capacity secondary batteries 9C and 9D as voltage holding means are provided, and a backflow prevention diode 2B and an opening / closing means 10 are arranged in parallel between the secondary batteries 9C and 9D and the positive output terminal 1a. It is provided in combination.

These secondary batteries 9C and 9D are also charged in the state where the solar cell module 3 is connected in series in the unit 4 to generate electric power, like the above-mentioned secondary batteries 9A and 9B, and the solar cell module 3 is charged. When the connection direction is switched, the discharge is performed to keep the potential of the positive electrode 3a of each connected solar cell module 3 at the potential before switching.

That is, it is desirable that the nominal capacities of the secondary batteries 9C and 9D are also set so that the short-circuit current (corresponding to the maximum output current) of the solar cell module 3 can be discharged for 1 hour or more. It is more preferable to set the size so that discharge can be performed for 5 hours or more in order to suppress the discharge. Then, it is desirable to select the types of secondary batteries 9C and 9D, the number of series, and the output characteristics of the solar cell module 3 to be combined in the same manner as the secondary batteries 9A and 9B described above.

This solar cell panel 1 includes an opening / closing means 7,
Opening and closing means 8 provided with 8, 10 provided between the positive electrode 3a of one solar cell module 3 and the negative electrode 3b of the other solar cell module 3 that are adjacent in the unit arrangement direction.
Since it is installed in the panel together with the solar cell module 3, it is preferable to use a voltage-driven switching element such as a MOSFET because of the convenience of storage and the power required for switching is small. Also,
The opening / closing means 10 can be arranged around the panel or inside the panel, and an electromagnetic relay may be used for convenience of storage, but it depends on the number of rows of the solar cell modules 3 arranged in a matrix. Because you need the number,
In order to suppress power consumption, it is preferable to use a voltage-driven switching element such as a MOSFET. Further, as the switching means 7, it is possible to use both a voltage-driven switching element such as a MOSFET and an electromagnetic relay.

FIG. 2 shows an example of the configuration of a battery charging circuit using the solar cell panel 1, which is designated by reference numeral 11.
Is a maximum output operating point tracking means, and this maximum output operating point tracking means 11 controls the load so that the output voltage and current of the solar cell panel 1 are output at maximum power. Reference numeral 12 is a power storage means capable of storing electric power for several days of the solar cell, and reference numeral 13 is a charge control means for controlling the charge amount of the power storage means 12. These maximum output operating point tracking means 1
1, the power storage means 12 and the charge control means 13 are also used in the conventional solar cell panel, but the maximum output operating point tracking means 11 has a built-in solar cell output voltage detection means and current detection means. Therefore, the voltage detecting means 5 and the current detecting means 6 may be used in common to reduce the price of the entire system.

Next, the operation of the solar cell panel 1 will be described. This solar cell panel 1 has three kinds of operation modes, and the opening / closing means 7,
The ON / OFF states of 8 and 10 are different, and the opening / closing means 8 and 10 provided by plural switches simultaneously in each operation mode. Table 1 shows the on / off states of the opening / closing means 7, 8, 10 in each operation mode.

[0032]

[Table 1]

In Table 1, the normal mode is an operation mode used when the vehicle is traveling and when the vehicle is parked in sunlight, and each solar cell module 3 is
The units 4 are connected in series, and each unit 4 generates power by sunshine. At this time, the secondary batteries 9A, 9B and 9 connected to the units 4A and 4C at both ends are connected.
C and 9D are directly connected to the negative output terminal 1b and the positive output terminal 1a, and are charged by the output of each solar cell module 3.

In Table 1, the switching mode means that the vehicle speed V becomes V = 0, all the units 4 partially enter the shadow S, and the output voltage of the solar cell panel 1 becomes as shown in FIG. Is a mode used when the output voltage decreases, and as shown in FIG. 5, the connection direction of the solar cell module 3 is switched to recover the output voltage.

In this switching mode, the solar cell modules 3 of the units 4 adjacent to each other are connected to generate power. At this time, the secondary batteries 9 connected to the units 4A and 4C at both ends by the backflow prevention diodes 2A and 2B.
Charging from A, 9B and 9C, 9D from each solar cell module 3 is blocked, and the secondary batteries 9A, 9B and 9C, 9D are switched to the discharged state, and the negative electrode 3b of each connected solar cell module 3 and The potential of the positive electrode 3a is maintained at the potential before switching.

An equivalent circuit in this state is shown in FIG. As shown in FIG. 6, the output current of the solar cell panel 1 flows in the direction of the arrow i, and the diode 2 arranged between the solar cell modules 3 in the unit 4 is in this switching mode circuit to obtain sunlight. The output current of the solar cell module 3 is prevented from flowing in the direction of the arrow i ′, that is, the short circuit via the solar cell module 3 entering the shadow S is prevented. The backflow prevention diodes 2A and 2B also have the same function as this, and the secondary battery connected to the solar cell module 3 in which the output current of the solar cell module 3 that receives sunlight enters the shadow S (see FIG. 6). Then, it is prevented from flowing back to the secondary battery 9B) as a charging flow.

Further, in this switching mode, the secondary batteries 9A, 9B and 9C, 9D function as current sources, and output the generated current of the solar cell module 3 which receives sunlight to the output terminals 1a, 1b. That is, in FIG. 6, when the secondary battery 9A, 9B and 9C, 9D is omitted and the circuit is configured by the diode 2 and the backflow prevention diode 2A, 2B, the current flows to the solar cell modules 3A, 3B closest to the output terminals 1a, 1b. The circuits are concentrated, and the current output capability of one solar cell module 3A (3B) is limited. Therefore, even if the sunshine is secured for the two series-connected circuits of the solar cell module 3, the output current is reduced to the level of one series-connected circuit of the solar cell module 3, and the amount of power that can be recovered is reduced. Since it decreases, by providing the secondary batteries 9A, 9B and 9C, 9D in the circuit,
A current corresponding to the output current of the solar cell module 3 is supplied to each series connection circuit of the solar cell module 3, and the generated current for the series connection circuit in which sunlight is obtained can be recovered.

Further, in this switching mode, since the secondary batteries 9A, 9B (9C, 9D) are directly connected to the solar cell module 3, the output voltage per solar cell module is set to Vm, and in the normal mode. When the number of series connections is n and the number of series connections in the switching mode is k, the output voltage of the switching mode is (k + n−1) × Vm with respect to the output voltage n × Vm of the normal mode, that is, the output voltage. Becomes higher (3Vm is 5Vm in Fig. 6)
become). This can be dealt with by designing with a margin in the input voltage range of the maximum output operating point tracking means 11 and the charging control means 13 to which the solar cell panel 1 is connected. When half or more of the panel 1 enters the shadow S and the output voltage drops to a fraction, it is possible to avoid the situation in which the storage means 12 cannot be charged.

In Table 1, the stop mode is a mode at night or when the entire solar cell panel 1 is in the shadow S, and the circuit state is the same as in the normal mode.
This is a state in which the output switching means 7 near the positive output terminal 1a is off, that is, a state in which no electric power is output.

That is, since the solar cell module 3 cannot obtain electric power when the sunshine is not obtained, the output opening / closing means 7 is turned off and the secondary batteries 9A, 9B and 9C, 9 are provided.
D is output terminals 1a, 1 via the solar cell module 3
It prevents it from discharging to b.

The above-mentioned three types of operation modes are selectively used according to the running state of the vehicle and the sunshine state of the solar cell panel 1, and the switching conditions for each mode are summarized in Table 2.

[0042]

[Table 2]

In Table 2, Vout is the output voltage of the solar cell panel 1 detected by the voltage detecting means 5,
Iout is the output current of the solar cell panel 1 detected by the current detection means 6. In addition, in a state where sunlight is obtained on the entire solar cell panel 1, the operating current of the solar cell panel 1 when the sun is southward is measured in advance,
The current value of 10% of this operating current is I _10, and the output voltage of the solar cell panel 1 measured when the sunshine is reduced and the operating current is actually I ₁₀ is V ₁₀ , and the mode switching determination is made. Use as a reference. Furthermore, in the state where one solar cell module 3 in the unit 4 is hidden, the output voltage and operating current of the solar cell panel 1 when the sun goes south are measured in advance, and this output voltage and operating current are measured. As Vs and Is respectively, when a part of the solar cell panel 1 enters the shadow S, all the units 4
Is used as a criterion for determining whether or not one or more solar cell modules 3 have entered the shadow S.

First, when the vehicle is parked with the system off, or when the speed v measured by the speed detecting means is v
When the traveling state is not = 0, the solar cell panel 1
There is no sunshine on the whole of the solar panel 1
When 10% of the operating current can not be expected (Vout <V
_{In 10} ), the stop mode is selected.

On the other hand, sunlight is obtained on the solar cell panel 1,
When 10% or more of the operating current of the solar cell panel 1 in the south central time can be expected (Vout ≧ V ₁₀ ), the normal mode is selected and the electric power is recovered.

Next, when the vehicle is system on but the speed v is temporarily stopped at v = 0, when a part of the solar cell panel 1 enters the shadow S, all the units 4
In, whether or not at least one solar cell module 3 has entered the shadow S is determined to have entered the shadow S when Vout <Vs and Iout <Is are satisfied (Is is the number of output currents in the time of south-central time). 1 / _10th , close to I ₁₀ ). Here, the reason why this determination is not performed only when Vout <Vs is that it is erroneously determined that the solar cell panel 1 has entered the shadow S even when the solar panel panel 1 is not in the shadow S even when the amount of sunshine has decreased. is there.

Then, the switching mode is selected, and if Iout ≧ I ₁₀ in this mode, it is judged that the series connection circuit of the solar cell modules 3 can be secured in the portion not in the shadow S, and the switching mode is selected. When Iout <I ₁₀ , the solar cell panel 1 is judged to have entered the shadow S and the stop mode is selected.

On the other hand, even during traveling, as shown in FIG. 4, all the units 4 may partially enter the shadow S. However, by installing the solar cell panel 1 on the vehicle body so that the connection direction of the units 4 is the traveling direction of the vehicle body, the boundary between the shadow S and the sunshine area is defined by the solar cell panel 1
As seen from the above, since the vehicle always moves in the opposite direction to the traveling direction, most of the time zone is when the entire panel 1 is in the shadow S or the entire panel 1 is in sunshine and is in the traveling state. In addition, even if the state shown in FIG. 4 occurs, the influence is small in terms of power recovery, and as shown in Table 2, it is possible to cope with the normal mode selected.

Further, there is a possibility that a part of the entire unit 4 in the solar cell panel 1 enters the shadow S at a right angle to the shadow S shown in FIG. However, in this case, since the electric power can be recovered from the unit 4 with sunlight, the normal mode may be selected as shown in Table 2 without selecting the switching mode.

That is, in the solar cell module connection direction switching control method of the present invention, the solar cell panel 1
Is preferably mounted such that the series connection direction of the units 4 faces the traveling direction of the vehicle body.

Therefore, in order to confirm the function of the solar cell panel 1, a solar cell panel was manufactured using an amorphous silicon solar cell module formed on a polyimide film. This amorphous silicon solar cell module has a size of 150 mm × 150 mm, and seven amorphous solar cells are installed in series. Four solar cell modules are arranged vertically and horizontally, and the total size is 800 mm × 800 mm. Sano solar cell panel.

First, a solar cell panel having no secondary battery connected to the units located at both ends was horizontally installed on the roof of the vehicle, and power was generated at the maximum output operating point when the sun was south in September. The output voltage of one solar cell module is 4.7 (V), the output current is 150 (mA), and the voltage of the part connecting the secondary battery with the lowest voltage is V1 is 4.2 (V). It was

Next, as a secondary battery, nominally 1.2 (V),
When three nickel-hydrogen batteries with a nominal capacity of 720 mAh were used in series and the charging characteristics were measured at a low current of 150 (mA), the battery voltage was 4.2 at a charging amount of about 50%.
Since (V) is shown, 6-series and 9-series secondary batteries were used at each connection point with the 3-series secondary battery as the minimum unit. The short-circuit current of the amorphous silicon solar cell module is 215 (mA), and the nominal capacity is 7
The 20mAh nickel-hydrogen battery has a short-circuit current of 3
It has the ability to discharge continuously for more than an hour.

The secondary battery is charged while operating the solar cell panel in the normal mode, and the output current at the time of south-central is 50
After recovering to 0 mA or more, when the sunlight of the four solar cell modules closest to the positive electrode side output terminal of the solar cell panel was cut off, the output voltage and output current of the solar cell panel were 11.6 (V) and 350, respectively. (MA). In the actual control, this is used as the determination reference, so when the connection direction of the solar cell module is changed by setting the operation mode of the solar cell panel as the switching mode, the output voltage 2
It operated at 4 (V) and an output current of 400 (mA).

Therefore, in the solar cell panel 1 described above, the structure is simplified, and even if the vehicle is stopped at a position where the solar cell panel 1 is partially shaded, It is possible to automatically switch the connection direction of the battery module, effectively recover the generated power of the portion where there is sunlight, and secure the output voltage.

The detailed structure of the solar cell panel according to the present invention is not limited to the above-mentioned embodiments.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of a solar cell panel according to the present invention.

FIG. 2 is an explanatory diagram of a configuration when the power storage unit is charged using the solar cell panel shown in FIG.

FIG. 3 is a circuit explanatory diagram when the solar cell panel shown in FIG. 1 is generating power in a normal mode.

FIG. 4 is a configuration explanatory diagram when a transition is made to the switching mode due to the shadow of the solar cell panel shown in FIG. 1.

5 is a circuit explanatory diagram when the solar cell panel shown in FIG. 1 is generating power in a switching mode.

6 is a circuit explanatory diagram equivalent to the circuit of FIG.

[Explanation of symbols]

1 solar panel 2 diode 3 solar cell module 4 units 5 Output voltage detection means 6 Output current detection means 8 opening and closing means 9A, 9B, 9C, 9D secondary battery (voltage holding means) S shadow

Claims (5)

[Claims] 1. A plurality of solar cell modules are connected in series to form a plurality of units connected in parallel,
In a solar cell panel in which solar cell modules of adjacent units are connected to each other so that the connection direction of the solar cell modules can be switched, a plurality of solar cell modules in the unit are connected in series via a diode and a unit array is arranged. A voltage-driven opening / closing means is provided between the positive electrode of one solar cell module and the negative electrode of the other solar cell module of the solar cell modules adjacent in the direction, and at one end side of the plurality of units arranged in parallel. For each negative electrode of the solar cell module in the unit located and each positive electrode of the solar cell module in the unit located on the other end side, a voltage holding that maintains the voltage before switching when the connection direction of the solar cell module is switched A solar cell panel provided with respective means. 2. The solar cell panel according to claim 1, wherein the voltage holding means is a secondary battery that is charged by the generated current of the solar cell module. 3. The secondary battery has a charge capacity capable of continuously discharging the power generation current of the solar cell module for 1 hour or more, and has a charge capacity of 2% of the charge capacity depending on the power generation current of the solar cell module.
The solar cell panel according to claim 2, which has a charging characteristic capable of charging 0% or more. 4. The solar cell panel according to claim 1, further comprising an output voltage detecting means and an output current detecting means. 5. The solar cell panel according to claim 4, wherein one of the solar cell modules in all the units is shaded,
A connection direction switching control method for a solar cell module, characterized in that the connection direction of the solar cell module is switched based on a decrease in both the output voltage and the output current detected by the output voltage detection means and the output current detection means.