Can you disconnect MC4 under load?

No, MC4 connectors should never be disconnected under load. If disconnected while current is flowing, it can cause:

Arcing: A potentially dangerous electrical arc can form between the contacts, leading to burns, equipment damage, or fire hazards.

Damage: The metal contacts of the connectors may be pitted or degraded, which could shorten their lifespan and compromise the integrity of the connection.

Safety concerns: There is a major chance of an arc when operating, which can be really dangerous when dealing with solar systems operating at 600V or higher.

How to properly remove MC4 Connectors:

Turn off the System:

Turn off current flow in the circuit with the use of a DC disconnect switch on a solar inverter or turning off the main breaker.

Testing Voltage:

A multimeter will ensure no voltage is in the system prior to disengaging the connectors.

Proper Use of Tool:

Use an MC4 connector tool to safely release the locking tabs and disconnect the connectors.

Special Cases:

If the system has to be disconnected under load, such as in emergencies or testing, then load break connectors or switches should be used since they are designed to interrupt current safely.
Safety first when it comes to solar electrical systems; if you’re not sure, ask a professional!

Summary

MC4 connectors shall not be connected or disconnected under load; doing so will create arcing that may lead to equipment damage or safety hazards. After switching off the power, use special tools to disassemble following the right steps to ensure safe operation of the system. If live operation is required, a specially designed load switch shall be used.