Operation unit related to solar power generation, solar power generation stop system, solar power generation system, and solar power generation method

Abstract

Operation unit for photovoltaic power generation, photovoltaic power generation stop system using the same, photovoltaic power generation system, and photovoltaic power generation method, capable of suppressing electric shock and fire caused by a photovoltaic power generation panel due to an earthquake and flood damage, and taking into consideration that a correct operation for stopping power generation is performed by preventing an operator's erroneous operation SOLUTION: An operation unit for a hybrid switch that is connected between terminals of a module or a string of a photovoltaic panel to obtain an output and short-circuits the terminals to stop the output includes a first manual switch corresponding to the hybrid switch, a seismic sensor, a water level sensor, a control unit that short-circuits the terminals in the hybrid switch under a predetermined condition, a second manual switch that restarts photovoltaic power generation from DC interruption by the control unit, and a display element that displays that power is being generated.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates to a highly convenient operation unit that can stop power generation by a solar power generation panel to prevent electric shock or fire in the event of an earthquake or flood, and to a solar power generation system and a solar power generation method that use the same. [Background technology]

[0002] Solar panels installed on homes can generate a maximum DC voltage of 400 volts. A typical solar panel generates a voltage of 30 to 40 volts, but it is said that a DC voltage of 40 volts can kill a human, so even a single solar panel can be dangerous.

[0003] In the United States, several firefighters were killed after being electrocuted by solar power generation equipment while fighting a fire. The installation of shut-off switches for solar power generation systems has been made mandatory by law, and other countries are also promoting this legislation.

[0004] In addition to electric shock, solar power generation has also led to fire accidents, and it has been reported that a fire at a mega solar power plant took more than 20 hours to be extinguished naturally because water could not be used to extinguish the fire.

[0005] Fire departments also recognize that the most dangerous thing during an earthquake is that solar panels could cause a fire, and it is believed that there was a high possibility of electrical fires (fires caused by electricity) in both the Great Hanshin Earthquake and the Noto Earthquake.

[0006] In the event of an earthquake or other large-scale disaster, it is extremely important to stop solar power generation in order to prevent secondary disasters such as electric shock and fire.

[0007] Regarding solar power generation, it is desirable to promote the spread of safe and secure solar power generation, rather than expanding its introduction while ignoring the dangerous aspects.

[0008] Here, Patent Document 1 discloses that a solar power generation panel is provided with a first sensor and a second sensor that observe the degree of danger, and that a switch is reversibly made non-conductive based on the observed value of the first sensor, and the switch is irreversibly made non-conductive based on the observed value of the second sensor.

[0009] Furthermore, Patent Document 2 discloses a hybrid switch that is connected between the DC output terminals of a module in a solar panel or a string of modules connected in series, and that obtains solar power output when the contacts are closed, but stops the solar power output by shorting the terminals via a semiconductor switch when the contacts are open. This hybrid switch suppresses arcing when interrupting DC power. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 4703202 [Patent Document 2] Patent No. 6940840 Summary of the Invention [Problem to be solved by the invention]

[0011] However, the above Patent Documents 1 and 2 do not sufficiently consider the need for an operating unit for solar power generation to respond to earthquakes and floods, which are common disasters in Japan, by automatically stopping power generation by the solar power generation panel when a predetermined level is reached, or by manually stopping power generation even when the predetermined level is not reached to prevent erroneous operation by the operator.

[0012] An object of the present invention is to provide an operating unit for solar power generation that can reduce electric shock and fire caused by earthquakes and floods in solar power generation panels, and that is designed to prevent operator error and ensure that power generation is stopped correctly, as well as a solar power generation stopping system, solar power generation system, and solar power generation method that use the same. [Means for solving the problem]

[0013] In order to achieve the above-mentioned object, the operation unit of the present invention is an operation unit for photovoltaic power generation that can be electrically connected to a hybrid switch that is connected between the terminals of the DC output of a module in a photovoltaic power generation panel or a string in which a plurality of such modules are connected in series, and that obtains photovoltaic power output when the contacts are closed, but stops the photovoltaic power output by short-circuiting the terminals via a semiconductor switch that is driven in a saturation region when the contacts are open, and that has: a manual first switch for selectively switching between power generation and power generation stop so that the contacts in the hybrid switch are selectively closed or open; a seismic sensor that detects earthquakes; a water level sensor that detects the water level of flooding; a control unit that cuts off the DC in the hybrid switch when the output of at least one of the seismic sensor and the water level sensor exceeds a predetermined value; a manual second switch that restarts power generation by the photovoltaic power generation panel after the DC current has been cut off by the control unit; and a display element that displays whether power is being generated by the photovoltaic power generation panel, wherein the first switch and the display element are provided on the front side of the operation surface, and the second switch is provided on the side side of the operation surface.

[0014] Preferably, the device is also electrically connectable to a power conditioner that converts power generated by the solar panel into alternating current when the contacts are closed, and a manual third switch for operating the power conditioner independently during a power outage is configured as a dual-purpose switch that also functions as the second switch, and the third switch is operated when the display element is on, and the second switch is operated when the display element is off. This makes it possible to reduce the size of the operation unit and simplify its operation.

[0015] Furthermore, the solar panel is characterized by having a power switch for generating power in the solar panel and a second display element for displaying that the power switch is on, on a side of the operation surface.

[0016] A photovoltaic power generation stopping system according to the present invention includes the above-described operation unit and the above-described hybrid switch.

[0017] A solar power generation system according to the present invention includes the operation unit, the solar power generation panel, and the hybrid switch.

[0018] A solar power generation system according to the present invention includes the operation unit, the solar power generation panel, the hybrid switch, and a power conditioner.

[0019] Furthermore, the solar power generation method of the present invention is characterized by having a first step of operating the solar power generation panel to generate power using a function of adjusting the voltage to the voltage that can convert sunlight into electricity most efficiently; a second step of selecting the first switch and manually stopping the output of solar power generation using the hybrid switch, or automatically stopping the output of solar power generation using a control unit when the output of at least one of the seismic sensor and the water level sensor exceeds a predetermined value; and a third step of resuming solar power generation using the second switch while the first switch is selected for power generation. [Effects of the Invention]

[0020] According to the present invention, electric shock and fire caused by earthquakes and floods to solar panels can be reduced, and erroneous operation by the operator can be prevented, allowing the correct operation to stop power generation to be performed. [Brief explanation of the drawings]

[0021] [Figure 1A] FIG. 2 is a front view of an operation unit that functions as a remote operation switch. [Figure 1B] 1 is a diagram showing a control unit, a seismic sensor, a water level sensor, a bracket for the water level sensor provided outside the operation unit, and a cable gland provided inside the operation unit. FIG. [Figure 1C] 1 is a conceptual diagram illustrating the appearance of a lever switch applied to an embodiment of the present invention. [Figure 2A] FIG. 2 is a view of the operation unit as seen from an oblique direction including the front and side. [Figure 2B] FIG. 2 is a view of the operation unit as seen from diagonally below, including the front and side surfaces. [Figure 3] (a) is a circuit diagram including a hybrid switch and an emergency stop switch as a device for stopping the output of a solar power generation system, and (b) is a block diagram of the emergency stop switch that operates based on the output of a seismic sensor and a water level sensor. [Figure 4A] FIG. 10 is a diagram showing a combination of an operation unit that functions as a remote operation switch as a solar power generation shutdown system, and a module-level safety switch that is connected to a solar panel. [Figure 4B] FIG. 1 shows a combination of string level safety switches connected to an operating unit and a solar panel. [Figure 5] FIG. 1(a) is a diagram explaining how to stop and start power generation using a manual lever switch, and FIG. 1(b) is a diagram explaining how to stop and start power generation using an emergency stop switch and a manual reset switch. [Figure 6] (a) is a diagram showing that solar panel power generation remains on even when household electricity is cut off, and (b) is a diagram showing that it can switch to independent operation in the event of a power outage. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] (First embodiment) (Solar power panels) Solar cell modules, which are photovoltaic (PV) power generation panels, are installed on roofs or other surfaces and generate electricity by being exposed to sunlight. Solar cell modules are packed with many small square objects called solar cell cells (hereinafter simply referred to as "cells"), each measuring approximately 10cm square, and each cell is a solar cell. Solar cell modules are treated with glass coatings and other processes to strengthen and protect them, and are sold as individual products.

[0024] A group of solar cell modules wired in series and connected together to generate a large amount of power is called a solar cell string (hereinafter simply referred to as a "string"). However, a group of solar cell modules wired in parallel to generate even more power and installed on a roof or other surface using a mounting system is called a solar cell array.

[0025] To ensure that the solar cell array satisfies a predetermined output voltage, each string is connected in parallel via a reverse current prevention diode (reference numeral 4 in Fig. 3(a) described later). This reverse current prevention diode is intended to prevent reverse current between the solar cell arrays due to voltage imbalance between the solar cell arrays when part of the solar cell array is shaded.

[0026] In addition, the bypass diode in the bypass circuit (reference numeral 5 in Fig. 3(a) described later) connected in parallel to the solar cell module serves to protect the solar cell module if it is shaded or malfunctions. In other words, if a solar cell module is shaded or malfunctions, it becomes difficult for current to flow through the defective part, so the bypass diode is provided to bypass this.

[0027] Small-scale solar power generation facilities can consist of around ten modules on the roof of a house, while large-scale facilities can have hundreds to tens of thousands of solar cell modules connected in series and parallel over a wide area.A single solar cell module has an output of around several tens of volts (V) and a few amperes (A), so there is little danger in handling it, but when a string is connected in series, the output can reach several hundred volts (400V to 1000V), which can be life-threatening if a person receives an electric shock.

[0028] (Operation unit) An operation unit having the function of a remote control switch for starting or stopping solar power generation is shown in FIGS. 1A, 1B, 1C, 2A, and 2B.

[0029] 1A is a view of the operation unit from the front side, and is equipped with only a lever switch 1 (see FIG. 1C) that can be manually switched between power generation and power generation stop, and a display element 2 that indicates power generation when power is being generated. This simple front operation panel allows the correct operation to stop solar power generation to be performed even with a momentary judgment (if the front operation panel had multiple operation points, it could be easy to make a mistake in the correct operation, but if the front operation panel has only one operation point, it is impossible to make a mistake in the correct operation). More specifically, if the operation unit according to this embodiment is placed outside, just outside the entrance, it can be operated to stop power generation without error when going out for an extended period of time, and the display element will turn off to confirm that power generation has stopped.

[0030] Furthermore, a plastic tamper-proof cover 110 (FIG. 2A) that can be opened and closed by an adult is provided, so that lever switch 1 can be prevented from being operated by children or the like.

[0031] FIG. 1B shows a control unit 20, a seismic sensor 30, a water level sensor 40, a bracket 50 for the water level sensor provided outside the operation switch, and a cable gland 60, all of which are provided inside the operation switch.

[0032] The functions of the control unit 20, seismic sensor 30, and water level sensor 40 will be described later in relation to Figure 3(b), but the water level sensor 40 detects a change in dielectric constant as a change in capacitance when the water level reaches a predetermined level in the event of a flood or other disaster in a container attached to the water level sensor bracket 50. Note that a cable leading to a module level safety switch or string level safety switch as a hybrid switch shown in Figures 4A and 4B is connected to the cable gland 60.

[0033] 2A and 2B are oblique views of the operation unit, including the front and side. The side of the operation unit is provided with a power switch 70, a power LED 80 as a second display element, a manual reset and independent operation switch 90, and an opening 100 for battery replacement.

[0034] The switch 90 has two functions: to resume power generation by canceling the power generation stop caused by the activation of the emergency stop switch (reference number 13 in Figures 3(a) and (b) described later) based on the seismic sensor 30 and water level sensor 40 (used for both resumption due to earthquakes and resumption due to floods), and to operate independently so that household electricity can be used during a power outage. This allows for the operation unit to be made smaller and easier to operate.

[0035] When power generation is stopped and power generation is resumed, the operation unit is operated with the display element 2 turned off, while when the unit is operated independently so that household electricity can be used during a power outage, the operation unit is operated with the display element 2 turned on, allowing for the use of both functions.

[0036] The following describes a hybrid switch that functions as either a module level safety switch or a string level safety switch.

[0037] (Hybrid switch) 3(a) is a circuit diagram showing an embodiment of a photovoltaic power generation output and output stopping device. 3 is a photovoltaic power generation module (PV module), and a plurality of these are connected in series to form a string. The photovoltaic power generation output stopping device according to this embodiment is interposed between the two positive and negative DC output wires of the photovoltaic module.

[0038] In Figure 3(a), the area enclosed by the dashed line constitutes the hybrid switch. Solar power is output via high resistance 10 only when reed relay 8 is in the on state, and when reed relay 8 is in the off state, the solar power generation module is short-circuited and enters a low voltage state.

[0039] When the permanent magnet 7 is brought closer, the reed relay 8 turns on, and when the permanent magnet 7 is moved away, the reed relay 8 turns off. The reed relay 8 is insulated from the emergency stop switch 13 and can turn on and off the MOSFET 6, which is a MOS type FET (field effect transistor), as a semiconductor switch; when the reed relay 8 is on, the MOSFET 6 turns off, and when the reed relay 8 is off, the MOSFET 6 turns on.

[0040] Here, a FET (field effect transistor) controls the current between the source S and the drain D by the voltage (gate voltage) applied to the gate G.

[0041] If drain resistor 11 is 0.5 Ω and the short-circuit current is 8 A, 0.5 × 8 = 4 V is returned to gate G, allowing MOSFET 6 to be driven into saturation and suppressing the on-voltage of MOSFET 6 to 1 V or less. In other words, because a low-resistance drain resistor is inserted into drain D, the gate voltage of MOSFET 6 can be increased by the voltage caused by this resistor, allowing MOSFET 6 to be driven in the saturation region (the on-voltage is also reduced) and reducing heat generation by MOSFET 6. In other words, the presence of drain resistor 11 on the drain D side for heat dissipation reduces heat generation during current flow in MOSFET 6 and suppresses arcing that accompanies switching on and off of DC current when conventional metal contacts are used.

[0042] Here, the lever switch 1 (Figs. 1A and 1B) of the operation unit is responsible for moving the permanent magnet 7 closer to or farther away from the reed relay 8. That is, when the manual lever switch 1 is in the power generation position, the permanent magnet 7 is moved closer to the reed relay 8, and solar power is output via high resistance 10 only when the reed relay 8 is in the on state. On the other hand, when the manual lever switch 1 is in the power generation stop position, the permanent magnet 7 is moved away from the reed relay 8, the reed relay 8 is in the off state, and the MOSFET 6 is turned on, shorting the positive and negative terminals of the solar module's DC output and stopping power generation.

[0043] The above-described hybrid switch can be summarized as follows: That is, the hybrid switch includes one n-type MOSFET 6 (hereinafter simply referred to as "MOSFET") that stops the output of generated power by short-circuiting the terminals of a photovoltaic power generation module or the like, a first resistor 10 having a high resistance value, a second resistor 11 having a low resistance value, and contacts that open and close the gate G and source S of the MOSFET 6, one end of the first resistor 10 is connected to the positive terminal of the photovoltaic power generation module or the like and the other end is connected to the gate G of the MOSFET, one end of the second resistor 11 is connected to the positive terminal of the photovoltaic power generation module or the like and the other end is connected to the drain D of the MOSFET 6, and the source S of the MOSFET 6 is connected to the negative terminal of the photovoltaic power generation module or the like, and when the contacts are closed, the MOSFET 6 is turned off to output the photovoltaic power generation module or the like, and when the contacts are opened, the MOSFET 6 is turned on to short-circuit the output of the photovoltaic power generation module or the like and stop the output of the generated power of the photovoltaic power generation module or the like.

[0044] Regarding the high resistor 10, when the reed relay 8 is short-circuited, the MOSFET 6 is turned off and the current from the solar power generation module flows into the high resistor 10, so it is necessary to reduce the loss current as much as possible and therefore to set the resistance value to be high.

[0045] Although the drain resistor 11 generates a large amount of heat, the temperature rise of the resistor is technically easier to deal with than in the case of a semiconductor switch.

[0046] A gate resistor 12 of 1 kΩ is recommended, which serves to prevent oscillation due to positive feedback since the MOSFET 6 is highly sensitive.

[0047] 3(a), reference numeral 9 denotes a reed relay drive coil. In this embodiment, if the reed switch is used as a reed relay 8 and the relay drive coil power is obtained from an adjacent PV module, a single short circuit can propagate in a chain reaction, shorting out all upstream PV modules at once, safely stopping power generation output.

[0048] (emergency stop switch) In Figure 3(b), if the outputs of the seismic sensor 30 and water level sensor 40 shown in Figure 1B exceed predetermined values, the control unit 20 can turn on the emergency stop switch 13 in Figure 3(a) to stop the output of generated power by short-circuiting the terminals of the solar power generation module, etc.

[0049] Specifically, in the event of a flood, if the water level in a container attached to the water level sensor bracket 50 reaches a predetermined position, the control unit 20 turns on the emergency stop switch and automatically stops power generation in the solar power generation panel.

[0050] Furthermore, the seismic sensor has the functions of an accelerometer and a displacement system, and when it detects shaking of a predetermined magnitude or greater, the control unit 20 turns on the emergency stop switch, automatically stopping power generation in the solar power generation panel.

[0051] (Solar power generation shutdown system) In this embodiment, the operation unit having the operation switch function and the module level safety switch or the string level safety switch can constitute a solar power generation shutdown system.

[0052] 4A shows a photovoltaic power generation shutdown system including an operation unit and module-level safety switches. Each module-level safety switch is connected to each photovoltaic panel and zeros the voltage for each module.

[0053] 4B shows a solar power generation shutdown system including an operation unit and string-level safety switches. Each string-level safety switch is connected to each string (multiple solar power generation panels) and sets the voltage of each string to zero.

[0054] In a string, multiple modules are connected in series, creating high voltages of several hundred volts (400V to 1000V), which can be life-threatening if a person is electrocuted. Therefore, each string level safety switch is equipped with a display element that displays "power generation in progress," and when power generation is stopped, this display element goes out, allowing visual confirmation that power generation has stopped.

[0055] The module-level or string-level safety switches mentioned above can also be equipped with an MPPT (maximum power point tracking) function, which adjusts the voltage to the level that can convert the most sunlight into electricity. When the amount of solar radiation and conditions (partial shading, etc.) differ between panels, MPPT for each panel can improve power generation efficiency by up to 40%.

[0056] (Temporal change in output from the halt of power generation to the restart of power generation) Figure 5(a) shows that lever switch 1 (Figure 1A) can be used to switch from the power generation position to the power generation stop position (switching solar panel power generation from on to off), and that lever switch 1 (Figure 1A) can be used to switch from the power generation stop position to the power generation position (switching solar panel power generation from off to on).

[0057] FIG. 5(b) shows that the solar panel power generation is switched from on to off by the emergency stop switch 13 (FIG. 3), and that the solar panel power generation is switched from off to on by the manual reset switch 90 (FIG. 2A).

[0058] Fig. 6(a) shows that solar panel power generation remains on even when the home electricity is out, and Fig. 6(b) shows that the home electricity can be switched on using solar panel power generation during a power outage by using the manual standalone operation switch 90 (Fig. 2A).

[0059] (Solar power generation system) The solar power generation system in this embodiment can include an operation unit having an operation switch function, a solar power generation panel, and a module level safety switch or a string level safety switch as a hybrid switch.

[0060] The system may also include an operation unit having an operation switch function, a solar power generation panel, a module level safety switch or a string level safety switch as a hybrid switch, and a power conditioner.

[0061] (Solar power generation method) The photovoltaic power generation method in this embodiment can be expressed as follows: That is, it has a first step of operating the photovoltaic power generation panel using a function of adjusting the voltage to the voltage that can best convert sunlight into electric power, a second step of selecting the first switch and manually stopping the output of photovoltaic power generation using the hybrid switch, or automatically stopping the output of photovoltaic power generation using a control unit when the output of at least one of the seismic sensor and the water level sensor exceeds a predetermined value, and a third step of manually selecting the first switch for power generation, or manually restarting photovoltaic power generation using the second switch while the first switch is manually selected for power generation.

[0062] (Variation) While the preferred embodiment of the present invention has been described above, the present invention is not limited to this embodiment and various modifications and variations are possible within the scope of the present invention. For example, although the manual reset and independent operation switch 90 shown in FIG. 2A is a combined switch, they may be separate switches. That is, a second manual switch for restarting power generation by the solar panel after DC power has been cut off by the control unit 20, and a third manual switch for operating the power conditioner, which converts power generated by the solar panel into AC power, in an independent operation state during a power outage, may be separate switches and disposed on the side of the operation unit.

[0063] Furthermore, the side surface on the side of the operation surface of the operation unit is not limited to a lateral (left-right) side surface, but may be an upward or downward side surface.

[0064] Furthermore, the seismic sensors and water level sensors may have mechanisms different from those described above but perform the same functions.

[0065] Furthermore, the reed relay and permanent magnet in the hybrid switch (FIG. 3(a)) may be replaced with a photocoupler driven by an infrared light emitting diode, or a photocoupler, reed relay and permanent magnet may be used.

[0066] Furthermore, the hybrid switch may have a built-in communication control device.

[0067] Furthermore, a photocoupler can be used and the permanent magnet 7 can be displaced between a position away from the emergency stop switch 13 and a position close to the emergency stop switch 13 . [Explanation of symbols]

[0068] 1··Lever switch (first switch), 2··Display element (first display element), 3··Photovoltaic power generation module (PV module), 6··MOSFET, 7··Permanent magnet, 8··Reed relay, 11··Drain resistor, 12··Gate resistor, 13··Emergency stop switch, 20··Control unit, 30··Seismic sensor, 40··Water level sensor, 50··Bracket for water level sensor, 70··Power switch, 80··Power LED (second display element), 90··Manual reset and independent operation switch, 100··Battery replacement opening

Claims

1. An operation unit for photovoltaic power generation that can be electrically connected to a hybrid switch that is connected between terminals of a DC output of a module in a photovoltaic power generation panel or a string in which a plurality of the modules are connected in series, and that obtains a photovoltaic power generation output when a contact is closed, and stops the photovoltaic power generation output by short-circuiting the terminals via a semiconductor switch that is driven in a saturation region when the contact is open, a manual first switch for selectively switching between power generation and power generation stop so that the contacts of the hybrid switch are selectively closed or opened; A seismic sensor that detects earthquakes; a water level sensor that detects the water level of the flooded area; a control unit that cuts off direct current in the hybrid switch when an output of at least one of the seismic sensor and the water level sensor exceeds a predetermined value; a second manual switch for restarting power generation by the solar power generation panel after the DC current has been cut off by the control unit; a display element that displays when the solar power generation panel is generating power; and An operation unit, wherein the first switch and the display element are provided on a front side of an operation surface, and the second switch is provided on a side side of the operation surface.

2. When the contacts are closed, the power conditioner can also be electrically connected to a power conditioner that converts power generated by the solar power generation panel into alternating current, A manual third switch for operating the power conditioner independently during a power outage, configured as a switch that can also be used as the second switch, the third switch is activated when the display element is in an on state; 2. The operation unit according to claim 1, wherein the second switch is operated when the display element is in an off state.

3. a power switch for causing the solar panel to generate power; a second display element that displays that the power switch is on; 2. The operation unit according to claim 1, further comprising: a key on a side of the operation surface;

4. An operation unit according to any one of claims 1 to 3; the hybrid switch; A solar power generation stopping system comprising:

5. An operation unit according to any one of claims 1 to 3; The solar power generation panel; the hybrid switch; A solar power generation system comprising:

6. an operation unit according to claim 2; The solar power generation panel; the hybrid switch; The power conditioner; A solar power generation system comprising:

7. A first step of operating the photovoltaic power generation panel according to claim 1 using a function of adjusting the voltage to a voltage that can convert sunlight into electricity most efficiently; a second step of manually stopping the output of the solar power generation by the hybrid switch by selecting the first switch according to claim 1, or automatically stopping the output of the solar power generation by the control unit when the output of at least one of the seismic sensor and the water level sensor according to claim 1 exceeds a predetermined value; a third step of manually restarting the solar power generation by the second switch according to claim 1 while the first switch is manually selected for power generation; or A solar power generation method comprising:

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