Standard test condition flash testing measured from the front and back of modules mounted on the near ground rack with −1500 V system voltage, (a), and an unbiased control mounted alongside, (b). Initial measurements were taken two weeks before application of system voltage. Final flash test measurements shown were taken after approximately 8 weeks of application of system voltage in the test field. I_sc is the short circuit current, V_oc, open circuit voltage; and P_max, the maximum power point.