Hitachi, Ltd.

Tetsuharu Ohya

Tomoharu Nakamura

Toru Kouno

Yuuichi Nagayama

Satoshi Miyazaki

Koki Morikawa

Hideyuki Shitanishi

Masahito Toyosaki

Kenichi Gokita

A diagnosis system including: a power collection unit configured to couple a plurality of photovoltaic cell arrays, each including photovoltaic cells, in parallel; a control unit; and a monitoring unit, the monitoring unit being configured to: estimate a solar radiation amount and an operating temperature of the photovoltaic cell arrays based on the current value measured by a first ammeter in the control unit and the voltage value measured by the first voltmeter in the control unit by using an expression expressing a relationship between the solar radiation amount, the operating temperature, and a number of photovoltaic cells, and an output current; correct the estimated values so as to match the current values measured by second ammeters in the power collection unit by using the expression; and calculate a theoretical current value of each of the photovoltaic cell arrays based on the corrected values by using the expression.

Diagnosis system and diagnosis method for photovoltaic power generation system

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

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Tokyo, Japan

Tetsuharu Ohya