Solar power generation system and failure diagnosis method therefor

A solar power generation system comprising:

• a solar battery array comprising a plurality of solar battery strings connected in parallel, each solar battery string comprising a plurality of solar battery modules connected in series,
• a plurality of string measurement units that, with a string current measurement device, measure a current through each of the plurality of solar battery strings;
• a sampling process unit receiving input from the string current measurement device, and supplying output to a signal conversion/transmission device;
• and
• a monitor device including a computer having a processor, a memory for storing programs, a storage device for storing necessary parameters, data, and measurement values, an output device, an input device, and a communication interface connecting the processor, the memory, the storage device, the output device, and the input device for communication, the computer configured to receive, via the communication interface, output from the signal conversion/transmission device permitting the processor to calculate a current loss in each of the plurality of solar battery strings and detect failure in each of the solar battery strings, wherein
• the input device acquires information about an amount of change in solar radiation in each of predetermined time bands in a day, and the processor extracts, from among the predetermined time bands of which the amount of change in solar radiation is smaller than a predetermined amount of change in solar radiation, a first time band indicating a minimum amount of solar radiation and a second time band indicating a maximum amount of solar radiation,
• the processor calculates, using a current value of the solar battery array in the first and second time bands, a reference current value of the solar battery string to be inspected in each of the first and second time bands,
• the processor calculates, from the measurement current value of the solar battery string to be inspected in the first and second time bands, the reference current value for the first time band, and the reference current value for the second time band, a first current loss in the first time band and a second current loss in the second time band,
• the processor detects, based on the first and second current losses, failure in any of the plurality of solar battery strings to be inspected, and
• the processor outputs to the output device by way of the communication interface a result indicating that the failure is present.

A failure diagnosis method for a solar power generation system including a solar battery array comprising a plurality of solar battery strings connected in parallel, each of the solar battery strings comprising a plurality of solar battery modules connected in series, the method comprising the steps of:

• providing a processor, a memory for storing programs, a storage device for storing necessary parameters, data, and measurement values, an output device, an input device, and a communication interface connecting the processor, the memory, the storage device, the output device, and the input device for communication,
• measuring, with a plurality of string measurement units having a string current measurement device and a voltage measurement device, a current and voltage of each of the plurality of solar battery strings;
• receiving, with a sampling process unit, input from each of the string current and voltage measurement devices;
• supplying output from the sampling process unit to a signal conversion/transmission device;
• acquiring, with the input device, information from the signal conversion/transmission device about an amount of change in solar radiation in each of predetermined time bands in a day, and extracting with the processor, from among the predetermined time bands of which the amount of change in solar radiation is smaller than a predetermined amount of change in solar radiation, a first time band indicating a minimum amount of solar radiation and a second time band indicating a maximum amount of solar radiation;
• calculating, using a ratio of operation current and short-circuit current in the solar battery array, an expected electric power value of the solar battery string to be inspected in each of the first and second time bands with the processor;
• calculating, from a measurement electric power value of the solar battery string to be inspected in the first and second time bands, the expected electric power value in the first time band, and the expected electric power value in the second time band, a first electric power loss in the first time band and a second electric power loss in the second time band with the processor;
• detecting with the processor, based on the first and second electric power losses, a failure in the solar battery string to be inspected;
• and
• outputting from the processor to the output device by way of the communication interface a result indicating the presence of the failure.