AbstractSecondary arc on solar arrays in space in defined as an arc discharge short‐circuiting adjacent solar cells. As the operational voltage of spacecraft increases to 100 V, there is more risk of secondary arc that can destroy solar array circuits. Secondary arc is categorized as a vacuum arc, although its current is very low, even less than 1 A. One‐dimensional modeling is carried out to derive sets of parameters that satisfy the governing equations. Genetic algorithm is used to find the optimal set of solutions. Even at a current less than 1 A, the solutions exist though the arc voltage is higher than the experimental values by several tens of volts. ©2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 1– 8, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20571