Can I Use Standard Electrical Disconnects for Solar?

Safety and Insulation Ratings

Standard electrical disconnects are not designed to handle the high-voltage and high-current requirements of a solar combiner box. According to the International Electrotechnical Commission (IEC) 60947-3, disconnects for photovoltaic (PV) applications must meet specific safety and insulation ratings. For example, a disconnect rated for a 1500V DC application must have an insulation level of at least 3kV AC for 1 minute, which is significantly higher than standard electrical disconnects.

Combiner Box Disconnect Requirements

A solar combiner box typically combines multiple string outputs to a single output, which can reach high voltages (up to 1500V DC). To ensure safe and reliable operation, disconnects in a combiner box must be designed to handle these high-voltages and currents. The disconnects should also meet the requirements of the National Electric Code (NEC) 690.11 for PV systems. This includes having a rating of at least 1500V DC, being able to interrupt the current without damage, and having a disconnecting means that can be operated with a single hand or foot.

Alternative Solutions

For solar combiner box applications, it is recommended to use disconnects specifically designed for PV systems. These disconnects typically have higher safety and insulation ratings, and are designed to meet the specific requirements of a combiner box. Examples of such disconnects include the Square D by Schneider Electric PV Disconnect Switch and the Eaton PV Disconnect Switch. These disconnects are designed to handle the high-voltages and currents of a solar combiner box, and provide a safe and reliable solution for disconnecting the system.