Abstract: A solar cell array used in a photovoltaic power generation apparatus for housing covers a relatively large outside area for installation, and a considerably large earth capacitance Ca exists between the solar cell array and the ground. Further, as an inverter for converting direct-current electric power generated by the solar cell array into alternating-current electric power, a transless-type inverter is used for reducing cost. Therefore, a slight leak current flows via the earth capacitance Ca, which may cause undesirable operation of an earth leakage circuit breaker inserted between the inverter and a commercial AC power system. In the photovoltaic power generation apparatus of the present invention, by designing it so that the relationship between the earth capacitance Ca[.mu.F] and leak current detection sensitivity EL[mA] of the earth leakage circuit breaker is Ca<EL/3, the undesirable operation of the earth leakage circuit breaker due to the leak current is prevented.

Abstract: In a ground fault protecting apparatus of this invention, which protects a solar power generation apparatus from a ground fault, when a ground fault generated in a solar cell array is continuously detected for a period longer than a time T1, a gate block signal for stopping the operation of an inverter connected between the solar cell array and a load is output first. When the ground fault is continuously detected for a period longer than a time T2 (>T1), a disconnection instruction signal for disconnecting the inverter from the load is output to the disconnection unit. According to the ground fault protecting apparatus of this invention, a high ground fault detection sensitivity can be set. In addition, the solar power generation apparatus can be prevented from being unnecessarily stopped due to erroneous ground fault detection.

Abstract: To reduce the capacity required for an external DC power source which supplies power for snow-melting and to prevent the problems associated with defective strings, the present invention comprises individually switchable current ON/OFF means provided for each string and a control unit for individually controlling the ON/OFF of said current ON/OFF means, thus enabling the sequential application of current to each single string.

Abstract: The control unit of a charge control apparatus for controlling charge of a storage battery connected in parallel to a solar cell panel has a voltage detector and a reference voltage generator for generating a reference voltage, both of which are connected in parallel to the storage battery, a delay device for delaying the output signal from the voltage detector by a predetermined time, and a comparator for comparing the signal delayed by the delay device with a reference signal generated by the reference voltage generator and controlling, in accordance with the comparison result, opening/closing of a switch for short-circuiting the output from the solar cell panel. With this simple arrangement, devices in the charge control apparatus can be protected even when the storage battery is disconnected for maintenance or the like.

Abstract: A conveying system comprising a pump whose power source is an unstable electric power supply, such as a solar cell; a first supply pipe for conveying liquid from an intake to the pump; a second supply pipe for conveying the liquid from the pump to a discharge opening; a liquid storage tank provided at a position which is below the discharge opening and above the pump; a third supply pipe branching from the second supply pipe, for conveying the liquid to the liquid storage tank; a fourth supply pipe connected between the liquid storage tank and the first supply pipe; a first valve, provided between the branching point of the first and fourth supply pipes and the intake, for opening and closing the first supply pipe; a second valve, provided between the branching point of the second and third supply pipes and the discharge opening, for opening and closing the second supply pipe; a third valve for opening and closing the third supply pipe; and a fourth valve for opening and closing the fourth supply pipe.

Abstract: To provide a cheap inverter which uses a single digital microprocessor and can execute a current control and a maximum power control without changing a design of a hardware even for any switching device or solar cell, there is provided a control apparatus of an inverter for converting a DC electric power into an AC electric power by using a switching device, wherein the control apparatus is constructed by an inversion discrimination circuit for receiving an output current or an output voltage and a reference signal and for discriminating whether a switching state of the switching device should be inverted or not and a gate pulse signal forming unit for changing the switching state of the switching device in response to an inversion request signal which is outputted from the inversion discrimination circuit. The gate pulse signal forming unit has a CPU for forming a gate pulse signal by an interrupting process by using the inversion request signal as an interruption control signal.

Abstract: In order to prevent a device serving as a load from being destroyed or causing an operation error while assuring an optimum operation voltage of a solar cell, and to stably, efficiently obtain power, a DC source system, in which a solar cell (1) and a DC source (3) are connected to an output terminal connected to a load (2) in parallel with each other, includes a first switch (5) arranged between the load (2) and the solar cell (1), a second switch 7 arranged between the load (2) and the DC source, and a capacitor (6) arranged between the load and the first switch in parallel with the solar cell.

Abstract: In order to provide an inverter apparatus and a solar power generation apparatus in which when a main AC power system (5) has suffered, e.g., a power failure, the operation mode of an inverter (2) in the tie operation with the main AC power system (5) can be easily and safely switched from the tie operation mode to the self-support operation mode, and electric power can be supplied to a load (4) directly using normal indoor wiring, the open/closed state of a switch (3) for opening/closing a connection between the output terminal of the inverter (2) and the main AC power system (5) is detected, and the self-support operation of the inverter (2) is started when the open state of the switch (3) is detected.

Abstract: In order to accurately and stably measure the output characteristics of a battery power supply device, especially, a large-scale solar cell module by an equipment that requires only a size and cost equivalent to those of an apparatus used for measuring a small-scale module, the light-receiving surface of the solar cell module is divided into areas each including a bypass diode, the output characteristics upon light illumination in units of divided areas are measured, the measured characteristics are synthesized, and the influence of bypass diode characteristics is subtracted from the synthesized characteristics, thereby calculating the output characteristics of the solar cell module.

Abstract: In a power control apparatus of a solar power generation system for converting power generated by a solar panel and supplying the converted power to a load, the output voltage and output current of the solar panel are sensed, and, under ordinary conditions, MPPT control is performed so that the solar cells will operate at a maximum output point. If the output power of the solar panel exceeds a predetermined power, a power conversion unit is controlled so as to raise the output voltage of the solar panel, thereby limiting the output power of the solar panel. As a result, excessive power is prevented from being output by the power control apparatus.

Abstract: A voltage control apparatus which is robust against disturbances such as variations in solar radiation amount around a solar cell, and has quick response, has a voltage detection unit (4) for detecting the voltage value of a battery power supply (1), a power conversion unit (2) for performing predetermined conversion of electric power supplied from the battery power supply, and supplying the converted electric power to a load or a commercial AC system (3), an output setting unit (5) for setting the output value of the power conversion unit on the basis of the voltage detection value, and a control unit (6) for controlling the power conversion unit on the basis of the output setting value. The output setting unit is constituted by a target voltage setting unit (51) for setting the target voltage value of the battery power supply, and an output calculation unit (52) for calculating the output setting value on the basis of the deviation between the voltage detection value and the target voltage value.

Abstract: In order to extract maximum power from a solar cell, maximum power point tracking (MPPT) control is performed under ordinary circumstances. If the output current of the solar cell becomes too small, the operating point of the solar cell is caused to fluctuate over a range wider than that of MPPT control at a period longer than that of MPPT control and the output voltage and current of the solar cell is sampled. In a case where it is indicated by power values obtained from the sample voltage values and current values that a plurality of maximal points of power value exist, a voltage value corresponding to a power value indicative of the largest value is set as the operating point of the solar cell.

Abstract: Power supplied from a battery power supply to a load through a power conversion unit is maximized with a relatively simple arrangement and a small processing load. In addition, an output command value for controlling the power conversion unit is detected, a set voltage for which the output command value is maximized is calculated with reference to a past or present set voltage, as needed, and set as the next set voltage such that the maximum output is supplied to the load without any erroneous operation in the case of variation in solar radiation. In this case, a plurality of voltages are sequentially set for a relatively short period. Output command values for the respective set voltages are fetched while setting the same voltage at the start and end of the operation. A variation in output command value caused by the fetching difference for the same set voltage is detected. The output command value for calculating the next set voltage is corrected in accordance with this variation.

Abstract: In a charge/discharge control system for a charging the output of a storage battery from a solar cell, the output voltage of the storage battery connected to a node between the solar cell output and a load is detected. If the detected voltage is less than a first setting value, discharge from the storage battery to the load is inhibited. The discharge inhibition is released in response to a discharge inhibition release command after the storage battery voltage increases to a second setting value.

Abstract: A power source apparatus includes a power generation device, a battery and an overcharge protection circuit. The overcharge protection circuit includes a shunt circuit, including a switching device for short-circuiting the power generation device when an input signal is at an `L` level. A reverse current protection circuit prevents an electric current from reversely flowing to the power generation device and/or the shunt circuit. A voltage detection section detects the voltage of the load or between the poles of the battery. An overcharge judgement section outputs an `L` level to the switching device when the voltage value detected by the voltage detection section surpasses a preset voltage value. When the voltage across the battery surpasses a predetermined value, the power source apparatus is short-circuited by the overcharge protection circuit, and therefore it is possible to prevent overvoltage from being applied to the load.

Abstract: A power control method and apparatus for extracting the maximum power from a battery power source are disclosed. Voltage signals and current signals are read while varying the operating point of a solar cell acting as the battery power source. The variation in the intensity of solar radiation that has occurred during a sampling time interval is estimated from a plurality of current signals, sampled at the same voltage, or, according to a plurality of power values, calculated from current signals and voltage signals. Based on the estimated variation in the intensity of solar radiation, the current signals or power signals are corrected. According to the corrected current signals or according to the corrected power values and the voltage values, the operating point is controlled so that the maximum output power is provided from the solar cell.

Abstract: It is an object of the invention to accurately detect a defective photoelectric conversion element regardless of the installation place and indicate the corresponding information. The above object can be achieved by a power generating system having a solar cell array constituted by a plurality of parallel-connected solar cell strings each consisting of a plurality of series-connected solar cell modules. The system includes electrical parameter detection units for measuring electrical parameters in solar cell strings, a comparing unit for mutually comparing the detected electrical parameters, and a unit for warning of an abnormality on the basis of the comparison result.

Abstract: A power control system for obtaining the maximum electric power from a battery power source. The system functions to vary an output voltage of the battery power source to obtain (m) power values from at least (m) voltage signals from a voltage detector and at least (m) current signals from a current detector which were sampled at desired intervals. A function is used which approximates the relations between the (m) voltage values and (m) power values. A voltage is calculated at which a power is set to a maximum value from the function and the (m) voltage and power values. The power is set at such a voltage into an output power set value and the output power of the battery power source is controlled.

Abstract: In a charging control method and apparatus which can improve the operating efficiency of a power generation system and prolong the service life of an accumulation unit, a short-circuit switch is closed, and a current generated in a solar cell is charged in the accumulation unit in a charging state. With this charging, the terminal voltage of the accumulation unit rises. This voltage is detected by a detection unit and is loaded into a control unit. When the detected voltage rises to a predetermined voltage, the short-circuit switch is closed by a short-circuit control signal. The output current from the solar cell is then discharged to the ground, and charging is stopped. In this state, the control unit determines the connected state of a load from an output signal from the detection unit.

Abstract: A battery power supply system permits inexpensive introduction of a transfer break system to a solar cell generation system and quick release of reverse charge phenomenon. The battery power supply system comprises a solar cell array (1), a DC-AC inverter (2), a break device (3) for a commercial power system, and wireless communication device (4) as control device for controlling the conduction and break of the break device based on the information derived through wireless communication.