JP2000022190A - Solar power generation system, controller and control method of snow melting for solar power generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove snow from the roof of a building in winter season in snowy area and to prevent power generation of solar cell from lowering due to snow. SOLUTION: Output parameters of solar cell, outer air temperature, solar radiation and/or time are detected and compared with preset values. A decision criterion is provided and a snow melting unit is operated when snow deposits on the surface of solar cells in a solar power generation system with snow melting function to cause lowering in power generation of solar cell. Surface snow is melted by heating the solar cell on the rear side and power generation capacity of solar cell is recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic power generation system that effectively prevents a decrease in output due to snow in a snowy area, and a snow melting control method for effectively preventing a decrease in output of the photovoltaic power generation system. is there.

[0002]

2. Description of the Related Art In recent years, a photovoltaic power generation system in which a solar cell is installed on a roof of a general house has been spreading. However, in a snow-covered area, there is a problem that the surface of the solar cell module is covered with snow during snowfall, and the solar cell cannot generate power.

The output voltage of each solar cell constituting a solar cell module is substantially fixed depending on the type of the solar cell, and the power generation capacity of the photovoltaic power generation system depends on the number of solar cell modules constituting the solar cell and the number of solar cells. It is determined by the light receiving area. Therefore, when designing a photovoltaic power generation system, in order to achieve a predetermined output voltage and a predetermined power generation capacity, a predetermined number of modules or a predetermined area of solar cells must be connected in series and parallel to form a system. No.

[0004] To obtain a larger capacity of power generation,
By increasing the number of photovoltaic modules in series and parallel,
It is feasible. In general, the power generation capacity of a solar cell is determined by the intensity of incident sunlight. However, when the solar cell is covered with snow during winter snowfall, the amount of power generation may drop sharply.

[0005]

In the above-mentioned conventional solar power generation system, when a part of the solar cell module is covered with snow during a snowfall in a snowy area, the power generation amount may suddenly decrease. In addition, when the entire surface is covered with snow, there is a problem that power is not generated at all.

That is, when snow accumulates on the surface of a solar cell in a snow-covered area, the power generation capacity of the solar cell is partially or entirely lost until it is completely melted. Therefore, in such snowy areas, the solar power generation system hardly operates in winter. Accordingly, an object of the present invention is to prevent a decrease in the power generation capacity of a solar cell due to winter snow in a snow-covered area, excluding the above-described drawbacks.

In snowy areas, regardless of the presence or absence of a photovoltaic power generation system, people climb on the roof during snowfall,
Perform snow removal work. Snow removal requires considerable expense and time. Accordingly, the present invention provides a photovoltaic power generation system that can not only take out electric energy cleanly by installing it, but also save the cost and time of snow removal,
Another object of the present invention is to provide a method and an apparatus for controlling snow melting.

[0008]

In order to solve the above problems, a solar power generation system according to a first aspect of the present invention includes a snow melting device, and further includes a solar cell for operating the snow melting device. Output parameter detecting means, the outside air temperature detecting means, at least one of the solar radiation intensity detecting means and the time detecting means, and at least one of these output parameters, the outdoor temperature and the solar radiation intensity and the time, Means for controlling operation.

Further, a method for controlling snow melting of a photovoltaic power generation system according to a second aspect of the present invention includes a step of detecting an output voltage of a solar cell and a step of detecting an outside air temperature. The snow melting operation is performed when the outside air temperature becomes equal to or lower than a preset value.

[0010] A snow melting control method according to a third aspect of the present invention, in addition to the second aspect, further comprises a step of detecting the intensity of solar radiation, wherein the output voltage and the outside air temperature are not more than predetermined values. When the solar radiation intensity is equal to or higher than a preset value, a snow melting operation is performed to melt the snow on the surface of the solar cell.

[0011] A snow melting control method according to a fourth aspect of the present invention, in addition to the second or third aspect, further comprises a step of detecting an output current of the solar cell. When the current falls below a preset value, a snow melting operation is performed to melt the snow on the surface of the solar cell.

A snow melting control method according to a fifth aspect of the present invention has a step of detecting a time in addition to any one of the above-described second to fourth aspects. When a predetermined time is within a predetermined time range, a snow melting operation is performed to melt the snow on the solar cell surface.

A snowmelt control apparatus according to a sixth aspect of the present invention includes a control means such as a CPU for executing the snowmelt control method according to any one of the second to fourth aspects, and comprises a snowmelt of a solar power generation system. The operation is controlled.

[0014]

According to the present invention, a photovoltaic power generation system is provided with a snow melting device, and by controlling the energization of the snow melting device, the snow accumulated on the surface of the solar cell is melted. I can do it.

Also, in snowy areas, regardless of the presence or absence of a solar power generation system, during snowfall, people climb on the roof,
Perform snow removal work. Snow removal requires considerable expense and time. ADVANTAGE OF THE INVENTION According to this invention, by attaching a snow melting device in addition to a photovoltaic power generation system, there is an advantage that not only the generation of electricity but also the cost and time for snow removal can be saved.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. Embodiment 1 As a photovoltaic power generation system 12 of the present embodiment, as shown in FIG. 2, a Canon laminated amorphous solar cell module having a photoelectric conversion layer formed by laminating three photoelectric conversion layers containing amorphous silicon. 13 (trade name BS-04) in 20 series and 5 parallel, and the roof 1 of the building
1 above. The total number of the solar cells is 100, the maximum output operation voltage is 140 V, and the maximum output operation current is 23 A
The standard solar cell output at this time is 3.2 kW in total.
(AM 1.5, 1 Sun, 25 ° C.). The connection box 14 for the solar power generation system is made of Canon BX-02,
The solar inverter 15 uses SI-01 manufactured by Canon. The solar inverter 15 is connected to a house switchboard (not shown).

As shown in FIG. 3, voltage dividing resistors R1 and R2 (Matsushita metal film resistors,
A PC card type data collection system 33 (NR-25 manufactured by KEYENCE) through R1 = 2 kΩ and R2 = 100 kΩ.
Enter 0). A T-type thermocouple 32 (manufactured by Hayashi Denko) is used as a means for detecting the outside air temperature. As a solar radiation detecting means, a pyranometer 31 with a fan (Eiko Hiroshi Solar Ace MS-62)
F) and attached at the same inclination angle as the installed solar cell 13, and the data collection system 33 (Keyence N
R-250). A personal computer 34 (FMV-5100NU / Fujitsu) for controlling the data collection system 33
Y notebook computer).

As the snow melting device 36, as shown in FIG. 4, the heater elements 21 are arranged in a zigzag arrangement between the back side of the metal reinforcing material of the solar cell module 13 installed on the roof 11 of the building and the roof 11. Formed and energized by an external power supply. The heater element 21 is formed by forming a flexible ribbon heater having an insulating coating into a heater pattern of an arbitrary shape, and directly attaching the flexible ribbon heater between the back surface side of the metal reinforcing material of the solar cell module 13 and the roof 11.

The heating means of the snow melting device 36 is not limited to the above-described flexible ribbon heater, but may be, for example, a silicon rubber heater or a thinned flat heater. In short, what is necessary is just to be able to heat the surface of the solar cell and melt the snow.

The control of the snow melting device 36 is performed by the personal computer 34 (notebook personal computer, Fujitsu FMV-510).
0NU / Y) to the digital / analog voltage converter 35 (A
Using a D / DA voltage output card, DAQcard-AO-DC manufactured by Japan National Instruments, the energization of the snow melting device 36 is switched by an analog voltage.

In the snow melting control method of the present embodiment, the following reference set values are used as set values for calculation. Reference solar radiation value I0 = 0.1 kW / m ² (1/3 of standard solar radiation)
10) Reference voltage value V0 = 70 V (1/2 of standard operating voltage) Reference outside air temperature T0 = 3 ° C.

The method of controlling snow melting is as follows. First, at regular time intervals, for example, every 30 minutes, the solar radiation intensity I1 from the pyranometer 31, the outside temperature T1 from the thermocouple 32, and R1 from the partial pressure resistors R1 and R2.
Of the voltage V1 between both ends is measured. The actual operating voltage V2 of the solar cell is calculated using the following conversion formula. V2 = V1 × ((R1 + R2) / R1)

Here, the measured solar radiation intensity I1 is compared with a reference solar radiation value I0. If the solar radiation intensity I1 is equal to the set value I0
If it is larger, the outside air temperature T1 and the operating voltage V of the solar cell
2 is compared with the reference outside air temperature T0 and the reference voltage value V0, respectively, and if T1 and V2 are smaller than the set values of T0 and V0, an operation signal of snow melting is output to the snow melting device 36.

After operating the snow melting device 36, the solar radiation intensity I1 is measured by the pyranometer, the outside air temperature T1 is measured by the thermocouple 32, and the solar cell operating voltage V2 is measured by the voltage dividing resistors R1 and R2 at regular time intervals, for example, every 30 minutes. Then, comparisons are made with the respective reference values, and the process is repeated according to the snow melting operation control method described above.

FIG. 1 shows a flowchart of the above snow melting control method. Here, due to the nature of the amorphous solar cell used in this example, a photodegradation phenomenon in which the performance deteriorates and stabilizes from the initial performance immediately after manufacturing due to long-term exposure to sunlight is generally known from academic research. Have been. On the other hand, it has also been found that this photodegradation is a reversible phenomenon that recovers to an initial value by annealing with heat. This is generally called annealing recovery. Therefore, according to the present embodiment, when power is supplied to the snow melting device, the solar cell is heated and the temperature rises, so that the recovery of annealing of the amorphous solar cell can be expected.

(Embodiment 2) The snow melting control apparatus of the present embodiment
The photovoltaic power generation system with the snow melting function of the first embodiment is provided with a current detecting means for the solar cell 13 and a personal computer 3.
4, when the conditions for energizing the snow melting device 36 in the first embodiment are satisfied, and when the current signal detected by the detection means becomes equal to or less than a preset value,
The decision is made to perform a snow melting operation, and the snow on the solar cell surface is melted.

Here, as means for detecting the current of the solar cell,
As shown in FIG. 5, a shunt resistor R3 (made by Dai-ichi Electronics, R3 = 0.1Ω) is attached between the junction box 14 of the photovoltaic power generation system and the solar inverter 15, and a voltage C1 across the shunt resistor R3 is applied. Input to the data collection system 33, the actual operating current C2 of the solar cell is calculated using the following conversion formula. C2 = C1 / R3

The snow melting control method of this embodiment is partially similar to the first embodiment as calculation set values, and uses the following reference set values. Reference solar radiation value I0 = 0.1 kW / m ² (1/3 of standard solar radiation)
10) Reference voltage value V0 = 70 V (１ ／ of standard operating voltage) Reference outside air temperature T0 = 3 ° C. Reference current coefficient C0 = 1/5 (１ ／ of standard operating current) Operating current S0 of standard state = 23 A

The method of controlling snow melting is as follows. First, at regular time intervals, for example, every 30 minutes, a solar radiation intensity I
1. The outside temperature T1 from the thermocouple 32, the voltage dividing resistors R1 and R2
Then, the voltage V1 across R1 and the voltage C1 across the shunt resistor R3 are measured. Then, the actual operating voltage V2 and operating current C2 of the solar cell are calculated using the conversion method described above.

Here, the measured solar radiation intensity I1 is compared with a reference solar radiation value I0. If the solar radiation intensity I1 is equal to the set value I0
If it is greater than, the outside air temperature T1 is compared with the reference outside air temperature T0. If T1 is smaller than the set value T0, the operating voltage V2 of the solar cell is compared with the reference voltage value V0. A snow melting operation signal is output to the apparatus to perform snow melting.

Here, if the solar cell operating voltage V2 is greater than the set value as compared with the reference voltage value V0, then the operating current C2 of the solar cell is converted to a current reference value C3 converted according to the following equation. Compare with And if the operating current C
If 2 is smaller than the current reference value C3, a snow melting operation signal is output to the snow melting device 36 to perform snow melting. Current reference value C3 = I1 × S0 × C0

After the snow melting device 36 is operated, the solar radiation intensity I is obtained from the pyranometer at regular time intervals, for example, every 30 minutes.
1. The outside air temperature T1 is measured by the thermocouple, the solar cell operating voltage V2 is measured by the voltage dividing resistors R1 and R2, and the measured values are compared with respective reference values.

FIG. 6 is a flowchart of the above-described snow melting control method. In the first embodiment, when only a part of the solar cell is covered with snow during winter snowfall, a voltage is generated due to sunlight being applied to the part not covered by snow, and the measured operating voltage of the solar cell is measured. When V2 is higher than the set reference value V0, the snow melting operation is not performed. However, in this embodiment,
Even when the solar cell is partially covered, there is an advantage that snow melting can be performed when the operating current C2 of the solar cell is measured and the calculated current reference value C3 is smaller than the calculated current reference value C3.

[0034]

The scope of the present invention is not limited to the above-described embodiment, but can be implemented with appropriate modifications.
For example, although an amorphous solar cell is used in the above description, a crystalline solar cell may be used. The means for detecting solar radiation is not particularly limited, and a sunshine meter may be used. Further, instead of detecting the outside air temperature, the temperature of the solar cell may be detected. Alternatively, both the outside air temperature and the temperature of the solar cell may be used. When detecting the temperature of the solar cell, since snow tends to remain at the lower level of the roof 11 during snow melting, it is more accurate to mount the temperature sensor for detecting the temperature of the solar cell at the lower level of the solar cell string. Can be.

[0035]

As described above, according to the present invention,
By installing a snow melting device in the solar power generation system and controlling the power supply to the snow melting device, it is possible to remove the snow on the roof of the building in the snow area and efficiently melt the snow accumulated on the surface of the solar cell. It can be used enough.

In particular, when snow accumulates on the solar cell surface of a solar power generation system having a snow melting apparatus and the power generation capacity of the solar cell is reduced, the operation control of the snow melting apparatus is performed by using the control method of the present invention. Melt the snow on the solar cell surface,
The power generation capacity of the solar cell can be restored.

[Brief description of the drawings]

FIG. 1 is a flowchart of a snow melting control method in the system of FIG. 2;

FIG. 2 is a configuration diagram of a roof of a photovoltaic power generation system according to an embodiment of the present invention.

FIG. 3 is a circuit diagram of the photovoltaic power generation system with a snow melting function of FIG. 2 including means for measuring solar radiation, outside air temperature, and solar cell voltage.

FIG. 4 is a configuration diagram of a roof of a solar power generation system with a snow melting function according to another embodiment of the present invention.

5 is a circuit diagram of the solar power generation system with a snow melting function of FIG. 4 including means for measuring solar radiation, outside air temperature, solar cell voltage, and solar cell current.

FIG. 6 is a flowchart of a snow melting control method in the systems shown in FIGS. 4 and 5;

[Explanation of symbols]

11: Building roof, 12: Solar power system, 13:
Solar cell module, 14: connection box for photovoltaic power generation system, 15: solar inverter, 21: heater element, 31: pyranometer, 32: thermocouple, 33: data collection system, 34: personal computer, 35: digital / analog conversion Machine, 36: snow melting control device, R1: resistance, R2: resistance,
R3: shunt resistance.

Claims (6)

[Claims] 1. A snow melting device for a solar cell, means for detecting an output parameter of a solar cell, means for detecting an outside air temperature, at least one of a means for detecting solar radiation intensity and a means for detecting time, Control means for controlling the operation of the snow melting apparatus based on at least one of an output parameter, an outside air temperature, a solar radiation intensity, and a time. Detecting an output voltage of the solar cell;
A method for controlling snow melting in a photovoltaic power generation system, comprising a step of detecting an outside air temperature, and performing a snow melting operation when the output voltage and the outside air temperature are equal to or less than a preset value. 3. The method according to claim 1, further comprising the step of detecting the solar radiation intensity.
The solar power generation system according to claim 2, wherein the snow melting operation is performed when the output voltage and the outside air temperature are equal to or less than a preset value and the solar radiation intensity is equal to or greater than a preset value. Snow melting control method. 4. The method according to claim 2, further comprising a step of detecting an output current of the solar cell, wherein the snow melting operation is performed when the output current is equal to or less than a preset value in addition to the above conditions. Or the snow melting control method of the photovoltaic power generation system according to 3. 5. The method according to claim 2, further comprising a step of detecting a time, and in addition to the condition, performing a snow melting operation when the time is within a predetermined time range. 4. The method for controlling snow melting of the photovoltaic power generation system according to any one of 4. 6. A snow melting control device comprising a control means for executing the snow melting control method for a photovoltaic power generation system according to claim 2. Description: