Abstract: To display the sum of power generation in a photovoltaic power generation system having a plurality of independently-operating inverters in real time, an information display device receives information indicative of amounts of power generation respectively outputted from the plurality of inverters, calculates the sum of power generation in the plural inverters based on the received information, and displays the result of calculation.

Abstract: In a solar power generation apparatus using a solar battery having a relatively large ground capacitor and a power conditioner having a non-insulated input and output, a customer's ground fault interrupter may perform unwanted interruption due to a ground fault outside the customer's premises. To prevent this, when a ground fault is detected by a detector capable of detecting a ground fault within a shorter time than the customer's ground fault interrupter, the gate of inverter of the power conditioner is blocked, a switch is changed to an open state, and the input voltage of inverter is held at a voltage value higher than the peak value of the alternate current voltage of a power system until at least the switch changes to the open state.

Abstract: A solar cell array is constructed by connecting plural solar cell strings in parallel, and the solar cell array is arranged to have strings of two or more rated voltages. This arrangement permits the solar cell array to be designed so as to maximize the output capacity in an area where the solar cells can be installed. In addition, the arrangement has high degrees of freedom of design to enable to construct a preferred configuration in terms of the design. Further, the solar cell array can be provided in a device configuration of low cost. Also provided is an array constructing method to facilitate installation and wiring.

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 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: 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: 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: 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.