Current, Voltage & Resistance Measurements

During PV system installation, many times you need to take measurements for current, voltage and resistance values using your Digital Multimeter (DMM). For correct measurement and safety purpose, following procedure should be adopted for:

Current Measurement

• Put on personal protective equipment (PPE) such as insulating gloves and safety glasses.
• Verify that you can safely place the meter's clamp around the conductor you want to measure. 
• Set the meter's dial to read the appropriate range of current.
• Zero the meter reading.
• Open the meter's clamp and place it around a single conductor.
• Read and record the current value from the meter.
• Remove the meter from the conductor.

Voltage Measurement

• Put on PPE.
• Make sure the circuit breakers are in the off state.
• Make the location where you want to take the voltage measurement accessible by removing the lids to the proper boxes, opening circuit breaker covers, or accessing the connectors on the back of the modules.
• Place the black meter lead in the connection point labeled Common on the meter.
•  Place the red meter lead in the connection point labeled V on the meter.
• Set the meter's dial to read  the appropriate range of voltage.
• Place the black lead on the negative terminal of the PV module.
• Place the red lead on the positive terminal of the PV module.
• Read the voltage measurement on the meter's screen.
• Switch the meter leads on the PV module and note the presence of the negative symbol.
• Remove the leads from the module and pull them from the meter.

Resistance Measurement 

• Put on PPE.
• Switch the AC and DC circuit breakers to the off state to remove any power source present.
• Make the location where you want to take the continuity measurement (continuous two terminals of conductor) accessible.
• Pace the black meter lead in the connection point labeled Common on the meter.
• Place the red meter lead in the connection point labeled omega (ohm).
• Set the meter's dial to read the circuit's resistance.
• Place the black lead on the first connection point.
• Place the red lead on the second connection point.
• Read the resistance measurement on the meter's screen or listen for the alarm that indicates a low-resistance connection.
•  Remove the leads from the modules and pull them from the meter.