In order to measure you're going to need to measure across the wires or terminals. Identify the solar panel labels, 2. The first step encompasses. The article explains how to determine the positive and negative terminals of a solar panel, crucial for proper installation to avoid energy wastage. It also discusses checking solar panel polarity and fixing reverse. For solar panel testing, you'll need a multimeter capable of measuring both DC voltage (since solar panels produce direct current) and current, ideally with a high amperage range. Female connectors are positive and male connectors are negative. Simply. Measuring their power output helps identify underperforming units, diagnose wiring issues, and maximize ROI.