To measure the voltage of a solar panel using a multimeter, set the meter to DC voltage (V) mode, connect the positive (red) probe to the panel's positive terminal, and the negative (black) probe to the negative terminal. Read the voltage on the display. A 1500V DC Multimeter is essential for accurate, safe measurement of high-voltage DC in photovoltaic applications. Standard multimeters max out at 1000V. Without proper testing and maintenance, solar panels can suffer from. How to measure the voltage and current of a mixed circuit? If you want to test the performance of your solar panel, you need to measure its voltage and current output.