JPH09128070A - Solar power generator - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] Extremely excellent reliability that can accurately detect an abnormality such as a shadow, dirt, disconnection, or short-circuit that occurs on the light-receiving surface of a solar cell module and reliably notify the user. To provide a revolutionary solar power generation device. SOLUTION: A plurality of solar cell modules (P1 to P4) connected in parallel to a load LD and feeding power to the load LD,
A conversion unit H for converting the electric power value of the solar cell module generating the maximum electric power out of the plurality of solar cell modules into a comparative electric power value lower than the electric power value, and a conversion unit H.
Photovoltaic power generation device having a detection means K for comparing the comparative power value converted by the above and the generated power value of each solar cell module to detect the solar cell module generating power at a power lower than the comparative power value. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar power generation device in which a plurality of solar cell modules are connected in parallel to supply power to a load, and in particular, shadows, stains, disconnections, and the like formed on the light receiving surface of the solar cell module. The present invention relates to a solar power generation device capable of accurately detecting an abnormality such as a short circuit and notifying the user of the abnormality.

[0002]

2. Description of the Related Art Conventionally, a solar power generation device in which power generated by a plurality of solar cell modules is supplied to a load has been used in remote areas such as remote islands and remote areas where power supply is difficult. However, in recent years, interest in the global environment has increased, manufacturing costs have dropped significantly,
Since the device performance is being actively improved, it is becoming even more familiar in general residential areas.

Further, research and development of interconnection systems between solar cells and existing electric power systems are being actively carried out. Especially, interconnection systems with commercial systems not only meet the peak cut demand of electric power demand, but also It has received much attention from the viewpoint of energy saving.

At present, a private house equipped with a solar power generation device capable of grid interconnection is being constructed and put into practical use. However, the installation place of the solar cell is generally a roof with various shapes. In addition, there is a problem that an ideal solar radiation state cannot always be realized. Furthermore, during the design stage when considering installation, even if ideal installation work is performed to prevent the occurrence of shade on the light receiving surface of the solar cell, shadows may occur due to the growth of trees over the years and neighborhoods A shadow may occur when a new house is built.

On the other hand, even in a medium-scale power generation system other than a private house, if the power generation scale is less than 100 kW, it is relatively easy to construct, so that it is idle in local public facilities, the roof of a parking lot, or the rooftop that is not used. Solar cell arrays have begun to be installed in, etc., and these solar cell arrays are usually composed of hundreds of solar cell modules and divided into dozens of strings.

Generally, the solar cells are maintenance-free, but, for example, the remaining snow in a snowy area may cause a shadow on a portion of the solar cell array, the effect of shadows caused by fallen leaves, and the partial light receiving surface. Deterioration of power generation may occur due to heavy dirt, dirt from volcanic ash, shadows of newly built buildings in the vicinity, and shadows caused by growth of trees.

In such a case, the reality is that there is no means for knowing the generation of shadows, stains, etc. other than visual inspection of the light-receiving surface of the solar cell module. In addition, due to the long-term use of the array structure of hundreds of sheets, a wiring cable disconnection accident or an accident such as a short circuit, a short circuit, a lightning strike, or a wire breakage caused by a hail rarely occurs. It is very difficult to find out if it is a problem.

Further, even in a small-scale array such as a system for a private house, since several strings are connected in parallel, the power generation output only decreases in these accidents that occur in some strings. It is difficult to find it. That is, it is difficult to distinguish a decrease in power generation and a decrease in solar radiation intensity from the characteristics of a solar cell that generates an output proportional to the solar radiation intensity, and there is also a problem that discovery will be significantly delayed even if an accident occurs. Was there.

[0009]

[Purpose] Therefore, the present invention solves the above-mentioned conventional problems,
An extremely reliable and innovative breakthrough that can accurately detect abnormalities such as shadows, stains, disconnections, shorts, etc. that occur on the light receiving surface of the solar cell module in a solar power generation device, and notify them to the user reliably. It aims at providing a simple solar power generation device.

[0010]

A solar power generation device that achieves the above object is a plurality of solar cell modules that are connected in parallel to a load and supply power to the load, and generate the maximum power of the plurality of solar cell modules. The conversion means for converting the power value of the solar cell module to a comparison power value lower than the power value, and the comparison power value converted by the conversion means and the generated power value of each solar cell module are compared. A photovoltaic power generation device having a detection unit that detects a solar cell module that is generating power with a power lower than the comparison power value.

Further, the detecting means is provided with a display section for specifying a solar cell module that is generating power with a power lower than the power value for comparison.

Here, the power value may correspond to not only power but also current or voltage.

For example, in order to detect a current difference flowing through each string of a solar cell array in which a plurality of solar cell modules are connected in parallel, attention is paid to an amount of voltage drop generated in an element inserted in series in each string, and the largest The circuit configuration is such that when the difference between the voltage drop amount and the voltage drop amount generated by the element inserted in series in each string is a certain value or more, it is determined to be abnormal.

Here, as an element to be inserted in series, for example, a breaker or a backflow preventing diode which is inserted in each existing string is used to reduce the normal output of the solar cell module without inserting a new element. I'm trying to detect.

Further, the purpose is to prevent variations in forward resistance and forward voltage drop characteristics of the reverse current prevention diode, etc., and to prevent erroneous detection caused by changes in temperature characteristics of the elements having the same forward characteristics. In order to prevent heat generation of the element as much as possible, a heat radiation fin is provided, the element is concentratedly mounted in the center of this heat radiation fin, a diode is inserted for each string, and the maximum value of the diode anode terminal voltage or Using the neighborhood value as a reference value, compare the anode terminal voltage of the diode for each string,
When a voltage difference of a certain value or more is generated, a circuit for emitting an alarm signal such as light or sound of an indicator lamp or displaying a liquid crystal is provided.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below.

First, the overall structure of the photovoltaic power generator PV according to the present invention will be described with reference to FIG. Each of the plurality of solar cell modules P1 to P4 is connected in parallel to the load LD via backflow prevention diodes D1 to D4 for preventing a backflow that occurs between the strings, and each of the solar cell modules P1 to P4. Circuit breakers S1 to S4 are provided between the reverse current prevention diodes D1 to D4 and the backflow prevention diodes D1 to D4.

Further, on the anode side of each of the backflow prevention diodes D1 to D4, there is provided a conversion means H composed of a diode OR circuit composed of diodes D9 to D13 and a variable resistor R1. This conversion means H is for converting the combined output at the point A1 of the solar cell modules P1 to P4 into a comparative output value lower than the combined output value (maximum power value) by means of the variable resistors R1 and R10. The output from the means H is input to the inverting input terminals of the comparators CP1 to CP4 forming the detecting means K described later. In the daytime, the OR circuit of the diodes D9 to D12 makes it possible to select the power (current) of the solar cell module that is generating the maximum power. In the daytime, no current flows in the forward direction of the diode D13. The diode D13 is provided to secure the voltages of the comparators CP1 to CP4.

On the other hand, in front of the conversion means H, a diode D is provided.
5 through D8, resistors R2 through R5 and resistors R6 through R
The voltage signal divided by 9 is input to the non-inverting input terminals of the comparators CP1 to CP4.

Here, in the detecting means K, the comparator CP
Outputs from 1 to CP4 are input to the control circuit CC, and when a low power solar cell module is detected continuously for a predetermined time, a light emitting diode (L1 to L1 which is a display unit connected to the strings of the solar cell module is detected. One of L4) is caused to emit light to call the user's attention. In addition to the light emitting diode, this display unit may be provided with a liquid crystal display or means for emitting an alarm sound.

The Zener diode Z1 provided in the detecting means K is provided as a power source for the comparators CP1 to CP4. The resistor R11 is provided for limiting the current of the Zener diode Z1. The capacitors C1 to C6 provided in each string are used as a filter for removing noise.

Since the solar cell produces an output which is almost proportional to the solar radiation intensity, generally the solar cell array (plural solar cell modules) is oriented in the same direction so that the solar radiation intensity of each string becomes uniform. It is usually installed. Therefore, in a normal array use state, the currents flowing through the respective strings have substantially the same value, i1 = i2 = i3.
= I4.

Solar cell array (solar cell module P1
If a shadow or stain is generated on a part of the pattern P4 to P4), the current of the strings decreases according to the ratio of the shadow or the like. By detecting this decrease in current, it is possible to detect which solar cell module has a shadow, is dirty, or has a reduced output due to disconnection. .

Next, the actual circuit operation for detecting this decrease in current will be described in detail. The current flowing through each of the strings has a voltage drop amount corresponding to the characteristics of the element in the backflow prevention diodes D1 to D4 inserted in series, the anode of the diode,
When the diodes, which are generated between the cathodes and are inserted into the respective strings, have the same characteristics, particularly the characteristics in the forward direction, the voltage drops of the respective strings do not differ.

Further, if the diode is dissipated in a radiator that dissipates heat so that the diodes are concentrated in the center of the radiator, the variation in element temperature between the diodes of each string becomes uniform. The forward characteristics will be complete. In order to obtain the maximum value of the anode voltage of each element having such a configuration, the voltages are combined by the OR circuit including the diodes D9 to D12.

Further, this voltage is applied to the comparators CP1 to CP4.
Divide the pressure so that it becomes an appropriate value for easy comparison. Further, the anode voltage of each element is taken out by the diodes D5 to D8, and similarly set to a predetermined value by a voltage dividing circuit including a resistor. By comparing the voltage values of the two by the comparators CP1 to CP4 provided for each string, it becomes possible to detect which string has a decreased current value.

For example, if it is assumed that the light receiving surface of the solar cell module P2 is shaded or that the strings have an obstacle such as a disconnection, the current flowing through the solar cell module P2 is smaller than the current flowing through the other strings. Therefore, the voltage drop caused by the backflow prevention diode D2 is also reduced. Therefore, the voltage at the non-inverting input terminal + side of the comparator CP2 becomes lower than the voltage at the inverting input terminal − side, and the output of the comparator CP2 becomes low. For this reason, L2 of the display unit KL of the detection means K is turned on, and the solar cell module P2 or its strings are abnormal (shadow or failure).
It is possible to remind the user that there is.

[0028]

As described above, in the photovoltaic power generator of the present invention, the existing backflow prevention diode can be utilized, and the abnormal output of the solar cell module can be detected with a very simple circuit configuration. .

Further, the abnormality can be displayed more effectively by combining not only the indicator lamp but also an appropriate alarm means. In particular, it becomes possible to call a very effective alert in a system for a private house where the condition of the roof cannot be easily checked.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a solar power generation device according to the present invention.

[Explanation of symbols]

 PV ・ ・ ・ Solar power generators P1 to P4 ・ ・ ・ Solar cell module H ・ ・ ・ Conversion means K ・ ・ ・ Detecting means LD ・ ・ ・ Loads S1 to S4 ・ ・ ・ Circuit breakers D1 to D13 ・ ・ ・ Diode R1 ... Variable resistances R2 to R10 ... Resistors C1 to C6 ... Capacitors CP1 to CP4 ... Comparator CC ... Control means Z1 ... Zener diode

Claims (2)

[Claims] 1. A power value of a plurality of solar cell modules connected in parallel to a load to supply power to the load and a solar cell module generating the maximum power of the plurality of solar cell modules is lower than the power value. For converting into a power value for use, and a solar cell generating power with a power lower than the power value for comparison by comparing the power value for comparison converted by the converter with the power value generated by each solar cell module. A photovoltaic power generation device comprising a detection means for detecting a module. 2. The solar power generation device according to claim 1, wherein the detection unit includes a display unit for identifying a solar cell module that is generating power with power lower than the comparison power value. A solar power generation device characterized in that.