AC Disconnect

An AC Disconnect, also known as an AC isolation switch, is a critical component in the solar industry that serves as a safety mechanism to disconnect the output of an inverter from the building’s electrical system. It is typically mandated by utility companies and electrical codes to ensure safety during maintenance, emergencies, or when grid connection needs to be terminated. The AC Disconnect is usually installed between the inverter and the main electrical service panel and can be manually operated. It facilitates the safe shutdown of a solar power system by isolating it from the grid, thereby preventing back-feeding electricity that could endanger utility workers or damage equipment during outages or repairs.

Common Applications

Residential Solar Installations

In residential settings, an AC Disconnect is used to separate the home’s solar power system from the grid, ensuring safety for both the property and the utility network.

Commercial and Industrial Solar Systems

For larger commercial and industrial solar power systems, the AC Disconnect serves the same fundamental purpose but often involves more robust equipment to handle higher power capacities.

Utility-Scale Solar Farms

Utility-scale solar farms also use AC Disconnects to safely manage the connection and disconnection of large arrays of solar panels from the grid, often integrating them into more complex electrical systems.

Safety Considerations

Protection for Utility Workers

The most significant safety consideration is the protection of utility workers. By isolating the solar system from the grid, the AC Disconnect prevents electricity from feeding back into power lines during maintenance or emergency situations.

Fire and Electrical Safety

Proper installation and use of an AC Disconnect can reduce the risk of electrical fires and ensure that solar systems can be quickly and safely shut down in case of an emergency.

Compliance with Electrical Codes

AC Disconnects must comply with local electrical codes and standards, which dictate their installation, accessibility, and operability to ensure maximum safety and effectiveness.

Related Terms or Concepts

Inverter

A device that converts direct current (DC) generated by solar panels into alternating current (AC) for use in homes and businesses.

DC Disconnect

Similar to an AC Disconnect, but used to isolate the DC side of the solar power system, typically between the solar panels and the inverter.

Grid-Tied System

A type of solar power system that is connected to the public electricity grid, often requiring an AC Disconnect to safely manage the connection.