Hitachi, Ltd.

Yuuichi Nagayama

Tomoharu Nakamura

Toru Kouno

Tetsuharu Ohya

Koki Morikawa

Satoshi Miyazaki

Masaaki Fujimori

Atsuhiko Kubo

A monitor device in a solar power generation system extracts a first time band indicating a minimum amount of solar radiation and a second time band indicating a maximum amount of solar radiation in a day, and calculates, using a ratio of operation and short-circuit currents in a solar battery array, an expected electric power value of a solar battery string to be inspected in each of the first and second time bands. From measurement electric power values of the solar battery string to be inspected in the time bands, the expected electric power value of the first time band, and the expected electric power value of the second time band, first and second electric power losses in the first and second time bands are calculated, and a failure in the solar battery string to be inspected is detected based on the first and second electric power losses.

Solar power generation system and failure diagnosis method therefor

A failure diagnosis system is configured to calculate an estimated irradiation on a first photovoltaic string and an estimated operating temperature of the first photovoltaic string based on a short-circuit current and an open-circuit voltage on a current-voltage characteristic of the first photovoltaic string, and the array output voltage value and the array output current value measured by an array measurement apparatus. The failure diagnosis system is configured to calculate an estimated current value of the first photovoltaic string based on the estimated irradiation, the estimated operating temperature, and the current-voltage characteristic. The failure diagnosis system is configured to diagnose degradation of the first photovoltaic string by comparing the measured current value of the first photovoltaic string and the estimated current value.

Failure diagnosis method and failure diagnosis system for photovoltaic system

The diagnostic method for a photovoltaic power system includes: a step of storing measured values of voltage and current outputted by a photovoltaic cell array, and identifying a first time period and a second time period with a lower solar radiation amount than in the first time period; a step of calculating the number of faulty photovoltaic cells on the basis of the measured values in the first time period; a step of calculating the number of faulty photovoltaic cells on the basis of the measured values in the second time period; and a step of comparing the number of faulty photovoltaic cells as calculated for the first time period, and the number of faulty photovoltaic cells as calculated for the second time period, and identifying a series resistance of the photovoltaic cells and a value indicating a degree of loss resulting from a fault in the photovoltaic cells.

Diagnostic method for solar power system and monitoring device

A power generating system comprising: a plurality of power generating units coupled in parallel; a power collecting device for collecting electric power output from the plurality of power generating units; and wirings for coupling the plurality of power generating units and the power collecting device. A ratio of a conductor diameter to a predetermined length of each of the wirings is defined as a reference ratio. A value obtained by multiplying the reference ratio, a number of the wirings, and a loss generated by a specific wiring together is subtracted from a value obtained by multiplying a predetermined number of wirings for adjustment by a ratio of a conductor diameter to a length of the specific wiring. A total of the ratios of the conductor diameters to the lengths of the predetermined number of the wirings for adjustment is determined as a value less than the subtracted value.

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Tokyo, Japan

Yuuichi Nagayama