Optical power generation device, optical power generation method, and snow-melting method

Abstract

To provide an optical power generation device, an optical power generation method, and a snow-melting method capable of efficiently generating power even at a time of snowfall when snow accumulates on optical power generation panels.SOLUTION: In a snow accumulation part of an optical power generation unit 110 in which panels with optical power generation modules converting light into power are connected in series, snow accumulates at a time of snowfall, and in a non-snow accumulation part, snow does not accumulate at the time of snowfall but generates power. Switchover means 120 switches a circuit between an optical power generation unit external device serial circuit connecting a power conditioner 200 using power generated by the optical power generation unit 110 and the optical power generation unit 110 in series, and a bypass circuit connecting an output terminal side and an input terminal side of the optical power generation unit 110 so as to bypass the power conditioner 200.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photovoltaic power generation device, a photovoltaic power generation method, and a snow melting method, and more particularly to a photovoltaic power generation device, a photovoltaic power generation method, and a snow melting method that convert received light into electric power. [Background technology]

[0002] BACKGROUND ART Conventionally, photovoltaic power generation has been developed in which light irradiated from the sun is received by a photovoltaic power generation panel having an array of solar battery cells, and the light energy is converted into electricity. However, these solar panels have a problem in that when snow accumulates on the surface of the solar panels, mainly in areas with heavy snowfall, the snow blocks sunlight, reducing the amount of power generated. For this reason, solar panels equipped with a snow-melting function to melt snow that has accumulated on the panels have been developed (for example, Patent Document 1).

[0003] FIG. 10 is a block diagram showing an outline of the snow melting device disclosed in Patent Document 1. As shown in FIG. 10, the snow melting device 10 disclosed in Patent Document 1 is intended to melt snow that accumulates on the light-receiving surface side of a solar panel 20 in a solar power generation device.

[0004] Specifically, the snow melting device 10 has a fluid inside it that functions as a heat medium, such as ethylene glycol, and is equipped with a snow melting unit 11 that is installed on the back side opposite the light-receiving surface of the solar panel 20 of the solar power generation device, a heating unit 12 for heating the fluid, a circulation unit 13 for circulating the fluid inside the snow melting unit 11, a control unit 14 for controlling the operation of the heating unit 12, the circulation unit 13, etc., and a power supply unit 15 for supplying power to the heating unit 12, the circulation unit 13, the control unit 14, etc.

[0005] In the snow melting device 10 disclosed in Patent Document 1, a heated fluid is circulated inside the snow melting unit 11 installed on the back side of the solar panel 20 by a heating unit 12 and a circulation unit 13 that operate using power supplied by a power supply unit 15, thereby melting the snow that has accumulated on the solar power generation panel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2024-002307 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the snow melting device 10 disclosed in Patent Document 1 has the problem that in order to circulate the heated fluid inside the snow melting section 11, it is necessary for the power supply section 15 to supply power to the heating section 12 and the circulation section 13, which means that it is very expensive to heat and circulate the fluid.

[0008] Generally, the energy conversion efficiency of solar panels currently available is said to be around 15% to 20%, making power generation efficiency poor. Heating a fluid using an external power source and circulating the heated fluid inside snow melting unit 11 just to melt the snow that has accumulated on the solar panels cannot be said to be efficient.

[0009] Furthermore, in order to heat the fluid and circulate the heated fluid inside the snow melting section 11, it is necessary to supply electricity from the power supply section 15 to the heating section 12 and the circulation section 13. Therefore, the snow melting device 10 disclosed in Patent Document 1 cannot be used in the absence of an external power source, which means that it is not possible to melt snow accumulated on a solar power generation panel in the absence of an external power source.

[0010] For example, it is possible to heat a fluid by supplying the electricity generated by the solar panel 20 to the heating section 12 and the circulation section 13, and to circulate the heated fluid inside the snow melting section 11, but if snow has accumulated on the solar panel 20, the solar panel 20 cannot generate electricity.

[0011] For this reason, the power generated by the solar panel 20 cannot be supplied to the heating unit 12 and the circulation unit 13. In other words, the snow melting device 10 disclosed in Patent Document 1 cannot melt the snow accumulated on the solar panel 20 using the power generated by the solar panel 20 itself.

[0012] The present invention has been made in consideration of these points, and aims to provide a photovoltaic device, a photovoltaic power generation method, and a snow melting method that can generate electricity efficiently even during snowfall when snow accumulates on the photovoltaic panels. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides a photovoltaic device that converts received light into electricity, characterized by comprising: a photovoltaic unit in which a snow-covered portion, which is a portion of a panel having a photovoltaic module that converts light into electricity, that is subject to snow accumulation when snow falls, and a non-snow-covered portion that is not subject to snow accumulation when snow falls, are connected in series; a photovoltaic unit-external device series circuit that connects the photovoltaic unit in series with an external device that uses the electricity generated by the photovoltaic unit; and a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic unit so as to bypass the external device.

[0014] As a result, in the photovoltaic power generation unit, in which panels having photovoltaic power generation modules that convert light into electricity are connected in series, snow accumulates in the snow-covered section when it snows, while electricity is generated in the non-snow-covered section when it snows, and the switching means switches between a photovoltaic power generation unit external device series circuit that connects the photovoltaic power generation unit in series with an external device that uses the electricity generated by the photovoltaic power generation unit, and a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit so as to bypass the external device.

[0015] The present invention also provides a photovoltaic power generation method for converting received light into electricity, comprising the steps of: a step of causing snow to accumulate on a snow-covered portion of a photovoltaic power generation unit in which panels having photovoltaic modules that convert light into electricity are connected in series; a step of causing snow to accumulate on a non-snow-covered portion of the photovoltaic power generation unit during snowfall, which generates electricity without accumulating snow; and a step of switching, when snow accumulates on the snow-covered portion, switching from a photovoltaic power generation unit / external device series circuit that connects the photovoltaic power generation unit in series with an external device that uses the electricity generated by the photovoltaic power generation unit to a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit so as to bypass the external device.

[0016] As a result, when snow falls, the snow-covered portion of the photovoltaic power generation unit, which is made up of panels connected in series and having photovoltaic modules that convert light into electricity, becomes snow-covered, while the non-snow-covered portion of the photovoltaic power generation unit generates electricity without being snow-covered, and when snow falls on the snow-covered portion, the switching means switches from a photovoltaic power generation unit external device series circuit, which connects the photovoltaic power generation unit in series with an external device that uses the electricity generated by the photovoltaic power generation unit, to a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit, bypassing the external device.

[0017] The present invention also provides a snow melting method using a photovoltaic device comprising a photovoltaic unit in which a snow-covered portion, which is a portion of a panel having a photovoltaic module that converts light into electricity, that accumulates snow when snow falls, and a non-snow-covered portion that does not accumulate snow when snow falls, are connected in series; a photovoltaic unit-external device series circuit that connects the photovoltaic unit in series with an external device that uses the electricity generated by the photovoltaic unit; and a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic unit so as to bypass the external device, characterized in that the snow melting method comprises: a step in which snow accumulates on the snow-covered portion when snow falls; a step in which the switching means switches to the bypass circuit; a step in which electricity is generated in the non-snow-covered portion without snow accumulating; a step in which the voltage generated by the non-snow-covered portion is applied to the snow-covered portion; and a step in which the snow-covered portion generates heat.

[0018] As a result, when snow falls, snow accumulates on the snow-covered area, the switching means switches to the bypass circuit, electricity is generated without snow accumulation in the non-snow-covered area, and the voltage generated by the power generation in the non-snow-covered area is applied to the snow-covered area, causing the snow-covered area to heat up. [Effects of the Invention]

[0019] According to the photovoltaic power generation device, photovoltaic power generation method, and snow melting method of the present invention, in a photovoltaic power generation unit in which panels having photovoltaic modules that convert light into electricity are connected in series, snow accumulates in the snow-covered areas when it snows, while electricity is generated in the non-snow-covered areas without snow accumulation when it snows, and a switching means switches between a photovoltaic power generation unit-external device series circuit that connects the photovoltaic power generation unit in series with an external device that uses the electricity generated by the photovoltaic power generation unit, and a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit so as to bypass the external device, thereby achieving the following effects.

[0020] The non-snow-covered area can generate electricity without snow accumulating even during snowfall, so when snow accumulates on the snow-covered area due to snowfall, the switching means switches to a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit so as to bypass the external device that uses the electricity generated by the photovoltaic power generation unit, and the voltage generated by the non-snow-covered area is applied to the snow-covered area that is connected in series with the non-snow-covered area.

[0021] However, the snow-covered area cannot generate electricity and has a high resistance, so the voltage generated by the non-snow-covered area is applied to the snow-covered area, which has a high resistance due to the snow, causing the snow-covered area to generate heat.As a result, the snow that has accumulated on the snow-covered area melts due to the heat generated by the snow-covered area.

[0022] In addition, when there is no snowfall and the snow-covered portion is not snow-covered, or when the snow that has accumulated in the snow-covered portion has melted, the snow-covered portion is not snow-covered and can generate electricity. Therefore, by switching the photovoltaic power generation unit to the external device series circuit, the power generated by the snow-covered portion and the non-snow-covered portion flows to the external device connected in series to the photovoltaic power generation unit.

[0023] Therefore, the snow can be melted by the heat generated by the snow-covered portion without the need for external power, meaning that efficient power generation is possible even during snowfall when snow accumulates on the photovoltaic panel. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 2 is a block diagram showing the concept of power generation modes in the photovoltaic device according to the first embodiment. [Figure 2] FIG. 2 is a block diagram showing the concept of a snow melting mode in the photovoltaic device according to the first embodiment. [Figure 3] 10 is a flowchart showing the process from when the control unit determines whether snow has accumulated on the snow-covered area to when snow melting on the photovoltaic power generation unit is completed. [Figure 4] 10 is a flowchart showing the process from when the temperature sensor detects the temperature of the snow-covered area to when the control unit operates to cause the switching means to switch from the power generation mode to the snow melting mode. [Figure 5] 10 is a flowchart showing the process from when the temperature sensor detects the temperature of the snow-covered area to when the control unit operates to cause the switching means to switch from the snow melting mode to the power generation mode. [Figure 6] 10 is a thermographic image showing the surface temperature of the snow-covered portion of the power generating section when the temperature rises due to switching the photovoltaic power generating device to snow melting mode. [Figure 7] FIG. 10 is a block diagram showing the concept of power generation modes in a photovoltaic device according to a second embodiment. [Figure 8] FIG. 10 is a block diagram showing the concept of a snow melting mode in a photovoltaic device according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing the concept of an example of installation of a non-snow-covered panel and a single-sided photovoltaic panel in a photovoltaic device according to a second embodiment. [Figure 10] FIG. 1 is a block diagram showing a snow melting device disclosed in Patent Document 1. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [First embodiment] FIG. 1 is a block diagram showing the concept of power generation modes in a photovoltaic device according to the first embodiment.

[0026] As shown in FIG. 1, the photovoltaic device 100 includes a photovoltaic unit 110, a switching means 120, and a control unit . The electricity generated by the photovoltaic power generation device 100 is connected to the photovoltaic power generation device 100 via a connection cable or the like, and is converted from DC power to AC power by a power conditioner 200, which is an external device that uses the electricity generated by the photovoltaic power generation device 100, and is sent to a distribution board or the like not shown here.

[0027] Here, the power conditioner 200 is shown as an example of an external device that uses the DC power generated by the photovoltaic power generation device 100 and converts it into AC power, but other devices can also be used as external devices that use the DC power generated by the photovoltaic power generation device 100 as long as they can use the electricity generated by the photovoltaic power generation device 100 as DC power.

[0028] The photovoltaic power generation unit 110 is a series connection of a photovoltaic panel having a photovoltaic module that converts light into electricity, and a double-sided photovoltaic panel 111 that generates electricity by receiving light irradiated from the sky and light reflected on the ground.

[0029] The photovoltaic device 100 is installed on the roof of a house, factory, warehouse, or vacant lot where there is nothing blocking sunlight. The photovoltaic unit 110 is preferably installed at an angle of about 30 degrees to the horizontal so that it is directly exposed to sunlight, but it can also be installed at any angle.

[0030] Specifically, the double-sided photovoltaic panel 111 has a front surface 111A on which the photovoltaic module generates electricity in response to light irradiated from the sky, and a back surface 111B on the opposite side of the front surface 111A on which the photovoltaic module generates electricity in response to light reflected on the ground, and the two surfaces are connected in series.

[0031] Photovoltaic unit 110 is installed at an angle of about 30 degrees with respect to the horizontal plane, so that when snow accumulates on photovoltaic unit 110 due to snowfall, front surface 111A of double-sided photovoltaic panel 111 becomes the snow-covered area where snow accumulates. In addition, back surface 111B is located on the opposite side of front surface 111A, and therefore becomes the non-snow-covered area where snow does not accumulate during snowfall.

[0032] The switching means 120 is used to switch between a photovoltaic power generation unit external device series circuit that connects the photovoltaic power generation unit 110 and the power conditioner 200 in series, and a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit 110 so as to bypass the power conditioner 200.

[0033] Specifically, the switching means 120 includes a first switching unit 121 that switches between connecting and disconnecting the connection line between the power conditioner 200 and the photovoltaic power generation unit 110, and a second switching unit 122 that switches between connecting and disconnecting the connection line connecting the output terminal side and input terminal side of the photovoltaic power generation unit 110.

[0034] When the first switching unit 121 is in a connected state and the second switching unit 122 is in a disconnected state, the photovoltaic device 100 becomes a circuit in which the photovoltaic power generation unit 110 and the power conditioner 200 are connected in series, and the power generated by the photovoltaic power generation unit 110 flows to the power conditioner 200.

[0035] This allows the power conditioner 200 to convert into AC power using the DC power generated by the photovoltaic power generation unit 110. Hereinafter, the state in which the switching means 120 switches the photovoltaic power generation unit 110 and the power conditioner 200 into a series circuit will be referred to as the power generation mode.

[0036] Furthermore, when the first switching unit 121 is in a disconnected state and the second switching unit 122 is in a connected state, the photovoltaic device 100 becomes a circuit in which the output terminal side and the input terminal side of the photovoltaic unit 110 are connected, i.e., a circuit in which the photovoltaic unit 110 is short-circuited. Hereinafter, the state in which the switching means 120 switches to a bypass circuit that bypasses the power conditioner 200 will be referred to as the snow melting mode.

[0037] By switching the circuit of the photovoltaic device 100 to the snow melting mode by the switching means 120, when snow accumulates on the photovoltaic unit 110 due to snowfall, that is, when snow accumulates on the surface 111A which is the snow-covered portion, it is possible to melt the snow.

[0038] Specifically, back surface 111B, which is a non-snow-covered portion, does not accumulate snow even during snowfall. In other words, even if front surface 111A accumulates snow due to snowfall, if there is light reflected on the ground, back surface 111B can receive that light and generate electricity.

[0039] When snow accumulates on the front surface 111A, which is the snow-covered portion, due to snowfall, the switching means 120 switches to snow melting mode, and the voltage generated by the back surface 111B, which is the non-snow-covered portion, is applied to the front surface 111A, which is the snow-covered portion, connected in series with the back surface 111B, which is the non-snow-covered portion.

[0040] However, when snow accumulates on surface 111A, the snow-covered portion cannot generate electricity because light is blocked by the snow. As a result, surface 111A, the snow-covered portion, cannot generate electricity and has a high resistance.

[0041] When the resistance of the snow-covered surface 111A is high, a voltage is applied to the snow-covered surface 111A due to the power generated by the non-snow-covered back surface 111B, causing the snow-covered surface 111A to generate heat. The heat generated by the snow-covered surface 111A can melt the snow that has accumulated on surface 111A.

[0042] Furthermore, when there is no snowfall and the snow-covered surface 111A is not covered with snow, or when the snow that has accumulated on the snow-covered surface 111A has melted, the snow-covered surface 111A is not covered with snow and can therefore generate electricity.

[0043] Therefore, when the switching means 120 switches the circuit of the photovoltaic device 100 from snow melting mode to power generation mode, the electricity generated by the front surface 111A, which is the snow-covered area, and the back surface 111B, which is the non-snow-covered area, flows to the power conditioner 200 connected in series to the photovoltaic device 110.

[0044] Therefore, photovoltaic device 100 of this embodiment can melt snow accumulated on surface 111A, which is the snow-covered portion, by generating heat from surface 111A, without requiring external power. In other words, even during snowfall when snow accumulates on photovoltaic unit 110, it is possible to generate power efficiently.

[0045] The control unit 130 is connected to the switching means 120 and controls the operation of the switching means 120, which switches between the photovoltaic power generation unit external device series circuit and the bypass circuit. Specifically, the first switching unit 121 and the second switching unit 122 are switched between connection and disconnection in response to an instruction from the control unit 130.

[0046] The control unit 130 is also connected to a snow accumulation condition determination means that determines the snow accumulation condition of the photovoltaic power generation unit 110, and depending on the snow accumulation condition determined by the snow accumulation condition determination means, the control unit 130 gives an instruction to the switching means 120 to switch between the power generation mode and the snow melting mode.

[0047] Specifically, the snow accumulation condition determination means is a temperature sensor 131 provided in a part of the photovoltaic power generation unit 110, and determines whether or not snow has accumulated on the photovoltaic power generation unit 110, i.e., whether or not snow has accumulated on the surface 111A that becomes the snow-covered part, based on the detected temperature detected by the temperature sensor 131 provided in particular on the back surface 111B, which is the back side of the photovoltaic power generation unit 110.

[0048] The snow accumulation state determining means can determine the snow accumulation state by monitoring with a camera in addition to the temperature sensor 131. The snow accumulation state may also be determined by a sensor that detects the snow accumulation height provided on the front surface 111A of the photovoltaic power generation unit 110.

[0049] When the control unit 130 determines that the surface 111A is covered with snow, the control unit 130 switches the circuit of the photovoltaic device 100 to a snow melting mode, and when the control unit 130 determines that the surface 111A is not covered with snow, the control unit 130 switches the circuit of the photovoltaic device 100 to a power generation mode.

[0050] More specifically, the snow accumulation condition determination means using the temperature sensor 131 determines that the surface 111A is snow-covered when the temperature sensor 131 remains below a predetermined temperature (for example, 0 degrees) at which it determines that there is snow accumulation for a predetermined time (for example, 300 seconds), and the control unit 130 switches the circuit of the photovoltaic device 100 to snow-melting mode.

[0051] Furthermore, when the temperature sensor 131 continues to maintain a predetermined temperature (for example, 10 degrees) or higher for determining a non-snow-covered state for a predetermined time (for example, 300 seconds), it is determined that the surface 111A is not covered with snow, and the control unit 130 switches the circuit of the photovoltaic device 100 to power generation mode.

[0052] As described above, the photovoltaic device 100 of this embodiment can melt accumulated snow using the heat-generating snow-covered portion without requiring external power. In other words, efficient power generation is possible even during snowfall when snow accumulates on the photovoltaic panel.

[0053] FIG. 2 is a block diagram showing the concept of the snow melting mode in the photovoltaic device according to the first embodiment. As shown in FIG. 2, by switching the switching means 120 to the snow melting mode, that is, by switching to a bypass circuit that bypasses the power conditioner 200, snow that has accumulated on the surface 111A that becomes a snow-covered area due to falling snow can be melted.

[0054] Specifically, back surface 111B, which is the non-snow-covered portion, does not accumulate snow even during snowfall. In other words, even if front surface 111A accumulates snow due to snowfall, back surface 111B can generate electricity by receiving light reflected from the ground.

[0055] When snow accumulates on the front surface 111A, which is the snow-covered portion, due to snowfall, the switching means 120 switches from the power generation mode to the snow melting mode, and the voltage generated by the back surface 111B, which is the non-snow-covered portion, is applied to the front surface 111A, which is the snow-covered portion, connected in series with the back surface 111B, which is the non-snow-covered portion.

[0056] However, surface 111A, which is the snow-covered portion, cannot generate electricity because the snow blocks light, and therefore surface 111A, which is the snow-covered portion, cannot generate electricity and has a high resistance value.

[0057] When the resistance value of the snow-covered surface 111A is high, a voltage is applied to the snow-covered surface 111A due to the power generation by the non-snow-covered back surface 111B, causing the snow-covered surface 111A to generate heat. The heat generated by the snow-covered surface 111A can melt the snow that has accumulated on surface 111A.

[0058] Furthermore, when there is no snowfall and the snow-covered surface 111A is not covered with snow, or when the snow that has accumulated on the snow-covered surface 111A has melted, the snow-covered surface 111A is not covered with snow and can therefore generate electricity.

[0059] Therefore, when the switching means 120 switches the circuit from the snow melting mode to the power generation mode, the power generated by the front surface 111A, which is the snow-covered area, and the back surface 111B, which is the non-snow-covered area, flows to the power conditioner 200 connected in series to the photovoltaic power generation unit 110.

[0060] Therefore, photovoltaic device 100 of this embodiment can melt snow accumulated on surface 111A, which is the snow-covered portion, by generating heat from surface 111A, without requiring external power. In other words, even during snowfall when snow accumulates on photovoltaic unit 110, efficient power generation is possible.

[0061] As described above, the photovoltaic device 100 of this embodiment can melt accumulated snow using the heat-generating snow-covered portion without requiring external power. In other words, efficient power generation is possible even during snowfall when snow accumulates on the photovoltaic panel.

[0062] 3 is a flowchart showing the process from when the control unit determines whether the snow-covered area is snow-covered to when the snow melting of the photovoltaic power generation unit is completed. The process shown in FIG. 3 will be explained below in order of step number.

[0063] [Step S11] The photovoltaic device 100 determines whether or not the surface 111A, which is the snow-covered portion, is covered with snow. Specifically, when the temperature sensor 131 continues to maintain a temperature below a predetermined temperature (for example, 0 degrees) that determines that a snow-covered state exists for a predetermined time (for example, 300 seconds), the control unit 130 determines that the surface 111A is snow-covered.

[0064] In step S11, if the control unit 130 determines that the surface 111A, which is the snow-covered portion, is covered with snow, the process proceeds to step S12, and if the control unit 130 determines that the surface 111A, which is the snow-covered portion, is not covered with snow, the process of step S11 is repeated.

[0065] [Step S12] The photovoltaic device 100 switches to the snow melting mode. Specifically, the control unit 130 operates the switching means 120 to switch to a snow melting mode, which is a bypass circuit that bypasses the power conditioner 200.

[0066] [Step S13] The photovoltaic device 100 determines whether or not the surface 111A, which is the snow-covered portion, is covered with snow. Specifically, when the temperature sensor 131 continuously maintains a predetermined temperature (for example, 10 degrees) or higher that determines that there is no snow on the surface 111A for a predetermined time (for example, 300 seconds), the control unit 130 determines that there is no snow on the surface 111A.

[0067] In step S13, if the control unit 130 determines that the surface 111A, which is the snow-covered portion, is not covered with snow, the process proceeds to step S14, and if the control unit 130 determines that the surface 111A, which is the snow-covered portion, is covered with snow, the process of step S13 is repeated.

[0068] [Step S14] The photovoltaic device 100 switches to a power generation mode. Specifically, the control unit 130 operates the switching unit 120 to switch to a power generation mode, which is a series circuit in which the photovoltaic power generation unit 110 and the power conditioner 200 are connected in series.

[0069] 4 is a flowchart showing the process from when the temperature sensor detects the temperature of the snow-covered area until the control unit operates the switching means to switch from power generation mode to snow melting mode. The process shown in FIG. 4 will be explained below in order of step number.

[0070] [Step S21] The photovoltaic device 100 detects the temperature of the surface 111A, which is the snow-covered area. Specifically, temperature sensor 131 provided on the back side of surface 111A, which is the snow-covered portion, detects the temperature of surface 111A, which is the snow-covered portion.

[0071] [Step S22] The photovoltaic device 100 determines whether the temperature of the surface 111A, which is the snow-covered portion, is a predetermined temperature at which it is determined that snow is present. Specifically, in step S21, the control unit 130 determines whether the temperature of the snow-covered surface 111A detected by the temperature sensor 131 is equal to or lower than a predetermined temperature (e.g., 0 degrees) at which the temperature of the snow-covered surface 111A is determined to be in a snow-covered state.

[0072] In step S22, if the control unit 130 determines that the temperature of the snow-covered surface 111A is below the predetermined temperature at which it is determined that snow has accumulated, the process proceeds to step S23; if the control unit 130 determines that the temperature of the snow-covered surface 111A is not below the predetermined temperature at which it is determined that snow has accumulated, the process of step S22 is repeated.

[0073] [Step S23] The photovoltaic device 100 determines whether a predetermined time has passed since the temperature of the surface 111A, which is the snow-covered portion, was first detected to be at a predetermined temperature at which it is determined that snow is present. Specifically, the control unit 130 determines whether a predetermined time (e.g., 300 seconds) has continuously elapsed since the temperature of the snow-covered surface 111A detected by the temperature sensor 131 in step S22 was first detected to be below a predetermined temperature at which the temperature of the snow-covered surface 111A is determined to be in a snow-covered state.

[0074] In step S23, if the control unit 130 determines that the temperature of the snow-covered surface 111A has remained below the predetermined temperature at which it is determined that snow has accumulated for a predetermined period of time, the process proceeds to step S24; if the control unit 130 determines that the temperature of the snow-covered surface 111A has not remained below the predetermined temperature at which it is determined that snow has accumulated for a predetermined period of time, the process proceeds to step S22.

[0075] [Step S24] The photovoltaic device 100 switches to the snow melting mode. Specifically, the control unit 130 operates the switching means 120 to switch to a snow melting mode, which is a bypass circuit that bypasses the power conditioner 200.

[0076] 5 is a flowchart showing the process from when the temperature sensor detects the temperature of the snow-covered area until the control unit operates the switching means to switch from the snow melting mode to the power generation mode. The process shown in FIG. 5 will be explained below in order of step number.

[0077] [Step S31] The photovoltaic device 100 detects the temperature of the surface 111A, which is the snow-covered area. Specifically, temperature sensor 131 provided on the back side of surface 111A, which is the snow-covered portion, detects the temperature of surface 111A, which is the snow-covered portion.

[0078] [Step S32] The photovoltaic device 100 determines whether the temperature of the surface 111A, which is the snow-covered portion, is a predetermined temperature at which it is determined that there is no snow. Specifically, the control unit 130 determines whether the temperature of the snow-covered surface 111A detected by the temperature sensor 131 in step S21 is equal to or higher than a predetermined temperature (for example, 10 degrees) at which the temperature of the snow-covered surface 111A is determined to be in a state where snow is not accumulated.

[0079] In step S32, if the control unit 130 determines that the temperature of the snow-covered surface 111A is equal to or higher than the predetermined temperature at which it is determined that the state is free of snow, the process proceeds to step S33; if the control unit 130 determines that the temperature of the snow-covered surface 111A is not equal to or higher than the predetermined temperature at which it is determined that the state is free of snow, the process of step S32 is repeated.

[0080] [Step S33] The photovoltaic device 100 determines whether a predetermined time has passed since the temperature of the snow-covered surface 111A was first detected to be a predetermined temperature at which it is determined that there is no snow. Specifically, the control unit 130 determines whether a predetermined time (e.g., 300 seconds) has continuously elapsed since the temperature of the snow-covered surface 111A detected by the temperature sensor 131 in step S32 was first detected to be equal to or higher than a predetermined temperature at which the temperature of the snow-covered surface 111A is determined to be in a state where there is no snow.

[0081] In step S33, if the control unit 130 determines that the temperature of the snow-covered surface 111A has remained above a predetermined temperature at which it is determined that the snow is not present for a predetermined period of time, the process proceeds to step S34; if the control unit 130 determines that the temperature of the snow-covered surface 111A has not remained above a predetermined temperature at which it is determined that the snow is not present for a predetermined period of time, the process proceeds to step S32.

[0082] [Step S34] The photovoltaic device 100 switches to a power generation mode. Specifically, the control unit 130 operates the switching unit 120 to switch to a power generation mode, which is a series circuit in which the photovoltaic power generation unit 110 and the power conditioner 200 are connected in series.

[0083] FIG. 6 is a thermographic image showing the surface temperature of the snow-covered part of the power generating section when the temperature rises due to switching the photovoltaic power generating device to snow melting mode. As shown in FIG. 6, the surface temperature of the photovoltaic power generation unit 110 rose to a maximum of 84° C., and sufficient heat was obtained to melt the snow that had accumulated in the snow-covered area.

[0084] Second Embodiment Next, a second embodiment of the present invention will be described. The photovoltaic device of this embodiment has substantially the same configuration as that shown in the first embodiment, except for the different shapes of the snow-covered portion, non-snow-covered portion, and switching portion. Therefore, components that are substantially the same as those of the first embodiment will be given the same reference numerals and their description will be omitted as appropriate.

[0085] FIG. 7 is a block diagram showing the concept of power generation modes in the photovoltaic device according to the second embodiment. As shown in FIG. 7, the photovoltaic device 100 includes a photovoltaic unit 110, a switching means 120, and a control unit .

[0086] The photovoltaic power generation unit 110 is a series connection of a single-sided photovoltaic panel 112, which has a photovoltaic panel with a photovoltaic module that converts light into electricity and is installed on the sky side so that snow can accumulate, and a non-snow-accumulated panel 113, which has a photovoltaic panel with a photovoltaic module that converts light into electricity in a state where snow will not accumulate when it snows.

[0087] The switching means 120 is used to switch between a photovoltaic power generation unit external device series circuit that connects the photovoltaic power generation unit 110 and the power conditioner 200 in series, and a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit 110 so as to bypass the power conditioner 200.

[0088] Specifically, the switching means 120 includes a branch switching unit 123 that branches and switches between a circuit that connects the connection lines that connect the output terminal side and input terminal side of the photovoltaic power generation unit 110 to the power conditioner 200, and a bypass circuit that disconnects the connection lines that connect the output terminal side and input terminal side of the photovoltaic power generation unit 110 to the power conditioner 200 and connects the output terminal side and input terminal side of the photovoltaic power generation unit 110 so as to bypass the power conditioner 200.

[0089] When the branch switching unit 123 switches to a circuit connecting the output terminal side and input terminal side of the photovoltaic power generation unit 110 with the power conditioner 200, the photovoltaic power generation device 100 becomes a circuit in which the photovoltaic power generation unit 110 and the power conditioner 200 are connected in series, and the power generated by the photovoltaic power generation unit 110 flows to the power conditioner 200. This puts the photovoltaic power generation device 100 into a power generation mode, similar to the photovoltaic power generation device 100 of the first embodiment.

[0090] Furthermore, the branch switching unit 123 cuts off the connection lines connecting the output terminal side and input terminal side of the photovoltaic power generation unit 110 to the power conditioner 200, and switches to a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit 110 so as to bypass the power conditioner 200, thereby short-circuiting the photovoltaic power generation unit 110. This puts the photovoltaic power generation device 100 into the snow melting mode, similar to the photovoltaic power generation device 100 of the first embodiment.

[0091] By switching the branch switching unit 123, which is the switching means 120, to the snow melting mode, when snow falls and accumulates on the photovoltaic unit 110, that is, on the single-sided photovoltaic panel 112 which becomes the snow-covered area, the accumulated snow can be melted.

[0092] Specifically, snow does not accumulate on the non-snow-covered panel 113, which is the non-snow-covered portion, even during snowfall. In other words, even if snow accumulates on the single-sided photovoltaic panel 112 due to snowfall, the non-snow-covered panel 113 can receive light and generate electricity.

[0093] When snow accumulates on the upper side of the single-sided photovoltaic panel 112, which is the snow-covered area, due to snowfall, the branch switching unit 123, which is the switching means 120, switches to snow-melting mode, and the voltage generated by the non-snow-covered panel 113, which is the non-snow-covered area, is applied to the single-sided photovoltaic panel 112, which is the snow-covered area, connected in series with the non-snow-covered panel 113, which is the non-snow-covered area.

[0094] However, the single-sided photovoltaic panel 112 in the snow-covered area cannot generate electricity because the snow blocks light, and therefore the single-sided photovoltaic panel 112 in the snow-covered area cannot generate electricity and has a high resistance.

[0095] A voltage is applied to the single-sided photovoltaic panel 112, which is the snow-covered part with a high resistance, due to the power generated by the non-snow-covered panel 113, which is the non-snow-covered part, and the single-sided photovoltaic panel 112, which is the snow-covered part, generates heat. The heat generated by the single-sided photovoltaic panel 112, which is the snow-covered part, can melt the snow that has accumulated on the single-sided photovoltaic panel 112.

[0096] Furthermore, when there is no snowfall and the single-sided photovoltaic panel 112, which is the snow-covered portion, is not covered with snow, or when the snow that has accumulated on the single-sided photovoltaic panel 112, which is the snow-covered portion, has melted, the single-sided photovoltaic panel 112, which is the snow-covered portion, is not covered with snow and can therefore generate electricity.

[0097] Therefore, when the branch switching unit 123, which is the switching means 120, switches the circuit to power generation mode, the electricity generated by the single-sided photovoltaic panel 112, which is the snow-covered area, and the non-snow-covered panel 113, which is the non-snow-covered area, flows to the power conditioner 200 connected in series to the photovoltaic power generation unit 110.

[0098] Therefore, the photovoltaic device 100 of this embodiment can melt snow accumulated on the single-sided photovoltaic panel 112, which is the snow-covered portion, by generating heat from the single-sided photovoltaic panel 112 without requiring external power. In other words, even during snowfall that causes snow to accumulate on the photovoltaic unit 110, efficient power generation is possible.

[0099] The control unit 130 is connected to the branch switching unit 123, which is the switching means 120, and controls the operation of the switching unit 120, which switches between the photovoltaic power generation unit external device series circuit and the bypass circuit. Specifically, the branch switching unit 123 switches the branch circuit in response to an instruction from the control unit 130.

[0100] As a result, the snow can be melted by the heat generated by the snow-covered portion without the need for external power. This means that efficient power generation is possible even during snowfall when snow accumulates on the photovoltaic panels.

[0101] FIG. 8 is a block diagram showing the concept of the snow melting mode in the photovoltaic device according to the second embodiment. As shown in Figure 8, by switching the branch switching unit 123, which is the switching means 120, to the snow melting mode, i.e., by switching to a bypass circuit that bypasses the power conditioner 200, it is possible to melt snow that has accumulated on the single-sided photovoltaic panel 112, which becomes a snow-covered area due to falling snow.

[0102] Specifically, snow does not accumulate on the non-snow-covered panel 113, which is the non-snow-covered portion, even during snowfall. In other words, even if snow accumulates on the single-sided photovoltaic panel 112 due to snowfall, the non-snow-covered panel 113 can still generate electricity by receiving light.

[0103] When snow accumulates on the single-sided photovoltaic panel 112, which is the snow-covered part, due to snowfall, the branch switching unit 123, which is the switching means 120, switches to snow melting mode, and the voltage generated by the non-snow-covered panel 113, which is the non-snow-covered part, is applied to the single-sided photovoltaic panel 112, which is the snow-covered part, connected in series with the non-snow-covered panel 113, which is the non-snow-covered part.

[0104] However, the single-sided photovoltaic panel 112 in the snow-covered area cannot generate electricity because the snow blocks light, and therefore the single-sided photovoltaic panel 112 in the snow-covered area cannot generate electricity and has a high resistance.

[0105] A voltage is applied to the single-sided photovoltaic panel 112, which is the snow-covered part with a high resistance, due to the power generated by the non-snow-covered panel 113, which is the non-snow-covered part, and the single-sided photovoltaic panel 112, which is the snow-covered part, generates heat. The heat generated by the single-sided photovoltaic panel 112, which is the snow-covered part, can melt the snow that has accumulated on the single-sided photovoltaic panel 112.

[0106] Furthermore, when there is no snowfall and the single-sided photovoltaic panel 112, which is the snow-covered portion, is not covered with snow, or when the snow that has accumulated on the single-sided photovoltaic panel 112, which is the snow-covered portion, has melted, the single-sided photovoltaic panel 112, which is the snow-covered portion, is not covered with snow and can therefore generate electricity.

[0107] Therefore, when the switching means 120 switches the circuit to power generation mode, the electricity generated by the single-sided photovoltaic panel 112, which is the snow-covered area, and the non-snow-covered panel 113, which is the non-snow-covered area, flows to the power conditioner 200 connected in series to the photovoltaic power generation unit 110.

[0108] Therefore, the photovoltaic device 100 of this embodiment can melt snow accumulated on the single-sided photovoltaic panel 112, which is the snow-covered portion, by generating heat from the single-sided photovoltaic panel 112 without requiring external power. In other words, even during snowfall that causes snow to accumulate on the photovoltaic unit 110, efficient power generation is possible.

[0109] As a result, the snow can be melted by the heat generated by the snow-covered portion without the need for external power. This means that efficient power generation is possible even during snowfall when snow accumulates on the photovoltaic panels.

[0110] FIG. 9 is a cross-sectional view showing the concept of an example of installation of a non-snow-covered panel and a single-sided photovoltaic panel in a photovoltaic device according to the second embodiment. FIG. 9(A) is a cross-sectional view showing an example in which a non-snow-covered panel 113 is installed perpendicular to a horizontal plane, and a single-sided photovoltaic panel 112 is installed at an angle to the horizontal plane.

[0111] 9(A), by installing the non-snow-covered panel 113 perpendicular to a horizontal plane, the power generating surface of the non-snow-covered panel 113 on which the photovoltaic modules are mounted is oriented horizontally, so that even during snowfall, snow does not accumulate on the surface of the non-snow-covered panel 113. In other words, the non-snow-covered panel 113 can be used as a non-snow-covered area.

[0112] Furthermore, by making the non-snow-covered panel 113 a double-sided photovoltaic panel 111 with photovoltaic modules on both the front and back sides, light irradiated onto the non-snow-covered panel 113 can be received by both surfaces facing the horizontal plane to generate electricity.

[0113] Furthermore, since the mono-facial photovoltaic panel 112 is installed at an angle to the horizontal plane, when it snows, snow accumulates on the surface of the mono-facial photovoltaic panel 112. In other words, the surface of the mono-facial photovoltaic panel 112 becomes a snow-covered area.

[0114] FIG. 9(B) is a cross-sectional view showing an example in which the snow-free panel 113 is installed on a wall W that extends in the vertical direction, and the single-sided photovoltaic panel 112 is installed horizontally. As shown in Figure 9(B), by installing the non-snow-covered panel 113 on a wall surface W that extends vertically, the power generating surface of the non-snow-covered panel 113 is oriented horizontally, so that even during snowfall, snow does not accumulate on the surface of the non-snow-covered panel 113. In other words, the non-snow-covered panel 113 can be used as a non-snow-covered area.

[0115] Furthermore, since the mono-facial photovoltaic panel 112 is installed horizontally, snow accumulates on the surface of the mono-facial photovoltaic panel 112 during snowfall. As shown in Figure 9(B), even if the single-sided photovoltaic panel 112 is installed horizontally, simply by switching the photovoltaic device 100 to snow-melting mode, the single-sided photovoltaic panel 112 can generate heat and melt the accumulated snow.

[0116] This means that, for example, by installing the single-sided photovoltaic panel 112 on the road surface, it is possible to prevent snow from accumulating during snowfall and melt any accumulated snow. As a result, the snow can be melted by the heat generated by the snow-covered portion without the need for external power. This means that efficient power generation is possible even during snowfall when snow accumulates on the photovoltaic panels. [Explanation of symbols]

[0117] 100 Photovoltaic device 110 Photovoltaic Power Generation Unit 111 Bifacial photovoltaic panel 111A Surface 111B back side 120 Switching Method 121 First change section 122 Second switching unit 130 Control Unit 131 Temperature Sensor 200 Power Conditioner

Claims

1. In a photovoltaic device that converts received light into electricity, a photovoltaic power generation unit in which a snow-covered portion, which is a portion of a panel having a photovoltaic power generation module that converts light into electricity, and a non-snow-covered portion, which is not subject to snow accumulation during snowfall, are connected in series; a switching means for switching between a photovoltaic power generation unit / external device series circuit that connects the photovoltaic power generation unit in series with an external device that uses the power generated by the photovoltaic power generation unit, and a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic power generation unit so as to bypass the external device; A photovoltaic device comprising:

2. a control unit that controls switching of the circuit by the switching means; The control unit When the snow-covered portion is snow-covered, the circuit is switched to the bypass circuit; When the snow-covered portion is not covered with snow, the circuit is switched to a series circuit of the photovoltaic power generating portion and the external device.

2. The photovoltaic device according to claim 1,

3. The control unit a snow accumulation state determination means for determining whether the snow-covered portion is covered with snow; 3. The photovoltaic device according to claim 2, wherein:

4. The snow accumulation state determination means determining whether or not the snow-covered portion is covered with snow based on a detected temperature detected by a temperature sensor provided in the photovoltaic power generation portion; 4. The photovoltaic device according to claim 3,

5. The control unit determining that the snow-covered portion is snow-covered when the detected temperature continues to be equal to or lower than a predetermined temperature for determining a snow-covered state for a predetermined period of time; 5. The photovoltaic device according to claim 4, wherein:

6. determining that the snow-covered portion is not snow-covered when the detected temperature continues to be equal to or higher than a predetermined temperature for determining a non-snow-covered state for a predetermined period of time; 5. The photovoltaic device according to claim 4, wherein:

7. The photovoltaic power generation unit is The double-sided photovoltaic panel has a front surface that is the snow-covered portion provided on the sky side and on which snow accumulates, and a back surface that is the non-snow-covered portion opposite the front surface, which receives light and generates electricity.

2. The photovoltaic device according to claim 1.

8. The non-snow-covered portion is The panel is installed vertically, The snow-covered portion is a single-sided photovoltaic panel in which the photovoltaic module is provided on the sky side, or a double-sided photovoltaic panel in which both the surface on which the photovoltaic module is provided on the sky side and the back surface opposite the surface receive light and generate electricity; 2. The photovoltaic device according to claim 1,

9. The snow-covered portion is To be installed on the road surface, 9. The photovoltaic device according to claim 8,

10. A photovoltaic power generation method for converting received light into electric power, A step in which snow accumulates on a snow-covered portion of a photovoltaic power generation unit in which panels having photovoltaic modules that convert light into electricity are connected in series during snowfall; a step of generating electricity without snow accumulation in a non-snow-covered portion of the photovoltaic power generation unit during snowfall; a step in which, when the snow-covered portion is snowed, a switching means switches from a photovoltaic unit / external device series circuit that connects the photovoltaic unit in series with an external device that uses the power generated by the photovoltaic unit to a bypass circuit that connects the output terminal side and input terminal side of the photovoltaic unit so as to bypass the external device; A photovoltaic power generation method comprising:

11. A snow melting method using a photovoltaic device comprising: a photovoltaic unit in which a snow-covered portion, which is a portion of a panel having a photovoltaic module that converts light into electricity, that is subject to snow accumulation when snow falls, and a non-snow-covered portion, which is not subject to snow accumulation when snow falls, are connected in series; a photovoltaic unit / external device series circuit that connects the photovoltaic unit in series with an external device that uses the electricity generated by the photovoltaic unit; and a bypass circuit that connects an output terminal side and an input terminal side of the photovoltaic unit so as to bypass the external device, A step in which the snow-covered portion is covered with snow during snowfall; a step of switching the switching means to the bypass circuit; generating electricity without snow accumulation in the non-snow-accumulated portion; applying a voltage generated by the non-snow-covered portion to the snow-covered portion; a step of generating heat in the snow-covered portion; A snow melting method comprising:

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