SOLAR CELL ARRAY DIAGNOSTIC SYSTEM, POWER CONDITIONER, SOLAR CELL ARRAY DIAGNOSTIC METHOD, AND PROGRAM

PROBLEM TO BE SOLVED: To diagnose electrical characteristics of a solar cell array by using a low cost and simple system, without obstructing power generation during solar irradiation, even when the solar cell array is in actual use for a long period.SOLUTION: When output of a solar cell array 12 is below a predetermined threshold, an input capacitor 26 is charged up to the open-circuit voltage of the solar cell, a SW2 is turned off, and then a SW3 except a SW3i is switched to a neutral contact c while the SW3i is switched to a contact a, thereby connecting a variable DC power supply 40 to the input capacitor 26 in series to apply a sum total voltage to a solar cell module string 16 in the i'th column, whereby transient voltage and current are measured to obtain the I-V characteristic of a voltage dependent region. The SW3i is switched to a contact b1 to get the input capacitor 26 temporarily discharged, and then the SW3i is switched to a contact b2 to measure transient voltage and current while the input capacitor 26 is charged, whereby the I-V characteristic of a current dependent region is obtained. The I-V characteristics of both regions are combined, and a series resistance R, a shunt resistance R, etc. are estimated, in which way the failure state of the solar cell array is diagnosed.