There are a few solutions to meet the new requirements of the NEC in regards the “rapid shutdown switch.” All solutions meet UL standards.
Bentek Solar offers a simpler solution that is comprised of a contactor box and control box. One is mounted on the roof within 10ft of the solar array and is operated by the control box mounted near the main service, the two components talk via control wire. Bentek is a more cost effective solution for smaller systems; one contact box handles up to 3 series strings.
Another viable solution, though a bit more costly is Midnite Solar’s RSS. Midnite Solar adds a combiner box into the disconnecting means on the roof, offering the ability to add up to 16 strings on a single disconnecting combiner box. It is then controlled by a control box in the same way as Bentek’s RSS solution. Midnite Solar’s RSS also opens all breakers if the communication line is ever severed and offers an automated voice speaker to audibly alert first responders of the situation on the roof.
At the moment, all UL listed solutions are only available in 600V applications though 1000V solutions are in the works.