Here's how a technician tests solar modules with a multimeter: Set the multimeter to DC voltage mode. Attach the black lead to the negative terminal. Based on real PV installation scenarios, the following five multimeter measurement techniques cover nearly all high-frequency operations at solar project sites and can significantly improve safety and diagnostic accuracy. Measure Voc (open circuit voltage) — if it reads 0V, the panel or wiring is dead. We will cover the. Multimeter testing is the standard approach for checking panel electrical characteristics. Fluke recommends using the Fluke 117 Electrician's Multimeter or Fluke 283 FC CAT III 1500 V Digital Multimeter to test solar modules.