Rooftop photovoltaic projects in Shenzhen are undergoing a substantial upgrade in acceptance standards. Shenzhen's local engineering construction standard SJG 220-2026 has been implemented , which sets precise quantitative indicators for rapid shutdown: the shutdown action should be completed in no more than 30 seconds, the voltage within 1 meter of the photovoltaic array should drop to below 80V, and the voltage outside 1 meter should drop to below 30V.
This isn't something that can be simply dismissed as "installing fast shutdown." On-site acceptance personnel will first locate all shutdown trigger points, confirming the consistency of logic at fire exits, near the inverter, and at the remote control terminal; then verify the correspondence between the shutdown devices and components; finally, record the time and voltage at the measurement points specified in the drawings, confirming that the array boundary, both inside and outside the project's adopted version, meets the requirements. Simply stating "RSD is written in the bill of materials" is no longer sufficient for acceptance; the system-level voltage control performance is the final criterion.
The Shanghai group standard T/ESETA 000007—2026 further refined the requirements: shutdown must be completed within 30 seconds after triggering, and the external voltage of the reachable boundary must be ≤30V, the internal voltage must be ≤120V, and the output power must be ≤1W. It also clearly states that "shutdown is divided into component-level and string-level, and component-level solutions should be given priority in densely populated places."
The North American market has more stringent entry barriers. NEC 690.12 requires that controlled conductors outside the array boundary must drop below 30V within 30 seconds, and that electric shock protection for firefighters within the boundary must be achieved through a listed PVHCS device or voltage limiting method. When selecting a PLC solution, the chip's modulation method and noise immunity directly determine the number of components the system can support.
This is a critical issue that is most easily overlooked by switch manufacturers and module purchasers.
The SunSpec Alliance's "Communication Signal for Rapid Shutdown" specification defines the communication protocol between the transmitter and receiver: the transmitter continuously sends a signal in an "operational" state, and the receiver triggers shutdown upon detecting a signal loss. The SunSpec Alliance explicitly states: "Only the 'SunSpec Certified' mark proves the complete and successful implementation of the SunSpec Rapid Shutdown communication signal functionality specification. Claims of 'SunSpec compliance' or 'SunSpec compatibility' by manufacturers or other third parties are not equivalent to a certificate issued by SunSpec."
This means that chip support for protocols, module passing conformance testing, and complete device certification are three independent verification levels.
Module-level protocol compatibility is only the first hurdle; safety certifications such as UL 1741 and CSA C22.2 at the whole-unit level are the passports to market entry. This understanding is crucial for circuit breaker manufacturers' selection decisions.
For circuit breaker manufacturers, the "PLC support" and "integrated line driver" features on the chip specifications are just the starting point. What truly determines whether a solution can be mass-produced and implemented is the engineering adaptability at the module level.
The first dimension is size. The circuit breaker is installed on the back panel of each photovoltaic module, where space is extremely limited, and it shares this limited area with junction boxes and cables. The module's package size directly determines the design space and installation method of the circuit breaker housing. PLC modules using the Hisilicon PS0211 chipset typically use a 28.12×18.00mm pin header package or a 20.0×14.2mm gold finger package, while some module manufacturers have launched a further miniaturized version of 20.0×11.0mm.
The second dimension is power consumption. The shutdown device is powered by the photovoltaic panel itself and has no independent power input. The static power consumption of the HiSilicon PS0211 solution is ≤0.15W (in the grid-connected, non-packet-sending state), and the dynamic operating power is ≤0.5W. During periods of insufficient sunlight, when the modules are shaded, or at night, the module must rely on extremely low standby power consumption to maintain its monitoring capability, waiting for the "operation allowed" signal sent by the inverter transmitter.
The third dimension is networking capability. PLC signals are transmitted via DC power lines, and the shutdown device, acting as a STA node, needs to establish a reliable communication link with the CCO at the inverter end. The HiSilicon PS0211 solution supports rapid networking in 10 seconds in a typical 200-node, 2-tier network scenario, supporting dynamic routing and multi-path addressing, and unicast, multicast, and broadcast command propagation methods. For the requirement of unified access for multiple components and devices in distributed photovoltaic systems, the networking scale and time performance of the modules directly affect the system commissioning efficiency.
In the selection of photovoltaic shutdown PLC modules, Qogrisysy provides two products based on different chip solutions, each corresponding to different engineering focuses.
the S130N-ISI (Linktronics VC6330 solution) is its ultra-small size. This module uses LCC packaging, with a PCB size controlled at 12.6×20.6×2.5mm. It operates in temperatures ranging from -20°C to 80°C and in storage temperatures from -40°C to 125°C, supporting SGCC 0~12MHz bandwidth and the IEEE 1901.1 communication protocol. For switchgear designs with extremely limited space, the physical size of the module is often the first screening hurdle.
For the design of rapid shutdown unit (RSU) enclosures where space is severely constrained, the physical dimensions of the module often serve as the primary screening criterion. For RSU manufacturers, engineering compatibility at the module level is more critical than specific chip parameters: the unit is mounted on the back of the PV module—an area with extremely limited space—and is powered by the PV panel itself, requiring it to continuously monitor PLC signals while operating at a microwatt-level power draw. Engineering metrics across three dimensions—module dimensions, power consumption characteristics, and reliability over a wide temperature range—directly determine whether the complete RSU can operate stably in real-world rooftop environments.
First, PLCs are the optimal technical solution for rapid shutdown at the component level. The SunSpec specification explicitly uses PLCs as the communication signal carrier, multiplexing DC power lines to transmit control signals, thus avoiding the cost and reliability risks of laying separate communication lines for each component.
Second, the acceptance criteria are shifting from "functionality" to "measurable effectiveness." The 30-second/80V/30V specifications in SJG 220-2026 and the quantitative requirements of the Shanghai group standard mean that the design of a fast shutdown solution must withstand on-site testing.
Third, the core consideration for module selection should shift from "chip parameters" to "engineering adaptability." The three engineering indicators—space constraints of the shutdown unit, power consumption constraints under self-powered conditions, and network scale constraints in distributed scenarios—are the key to determining whether a solution can be mass-produced and implemented.
Fourth, awareness of certification levels is a capability that circuit breaker manufacturers must establish. Chip support for the SunSpec protocol, module certification through SunSpec, and complete unit certification through UL 1741 safety standards are three independent verification levels. The Hisilicon PS0211 chip explicitly indicates support for the SunSpec standard, and the Qogrisysy 3121N-H module, based on this chip, provides a fundamental protocol-level guarantee for circuit breaker manufacturers' complete unit certification.
Fifth, the role of module suppliers is expanding from "device delivery" to "certification assistance." Switch manufacturers need more than just "usable modules"; they need technical partners who can "help understand SunSpec test logic, optimize system networking design, and assist in passing overall system certification."
