After years of working in PV O&M, I’ve noticed that many technicians feel frustrated when rapid shutdown solar devices malfunction—either failing to trigger shutdown, being unable to resume operation after shutdown, which not only delays power generation but also poses potential safety hazards. In fact, most faults are not major issues; as long as you find the right troubleshooting direction, they can be resolved in more than ten minutes. Today, I’ll organize the common problems I’ve encountered, along with troubleshooting steps and solutions—all practical insights. Fonrich’s devices also have many user-friendly designs in this regard, helping everyone avoid detours.
Fault Symptom: Whether pressing the on-site physical switch or triggering remotely via a mobile App, the rapid shutdown solar device shows no response. The voltage on the module side remains high, and power cannot be cut off.
Troubleshooting Steps & Solutions:
First, check the power supply — Rapid shutdown solar devices rely on module power to operate. If a string of modules is not generating power (e.g., due to shading or loose wiring), the device will "have no power to work." Use a multimeter to measure the voltage at the device’s input terminal. If it is lower than 5V, it is a power supply issue. First, tighten the module wiring, clear any shading, and test again after power supply is restored.
Then, check the communication cable — If remote triggering fails, the RS485 communication cable may be loose or broken. Fonrich’s devices have a communication indicator light: a steady green light indicates normal operation, while a blinking or unlit light signals a communication problem. Trace the cable to check the connectors, reinsert them firmly, or replace the cable if necessary.
Finally, check the trigger mode — Some devices have an "auto/manual" switch; if it is accidentally toggled to the "disable" position, the device will not respond. Fonrich’s devices display the current mode in the App. If it is incorrectly set to "maintenance disable," switching it back to "normal mode" will make it work immediately.
In a previous community project, there was no response when triggering shutdown. After checking, it was found that the communication cable had been chewed through by a rat. Replacing the cable and reconnecting it took only 5 minutes to fix the problem.
Fault Symptom: After triggering shutdown, the voltage drops to a safe value, but when attempting to resume power generation—whether pressing the reset button or operating remotely—the device shows no response. The modules remain without voltage, and the entire string cannot generate power.
Troubleshooting Steps & Solutions:
First, wait for the "recovery delay" — Many devices have a 5-10 second delay protection after shutdown; they do not resume immediately after pressing reset. You need to wait for the delay to end before trying again. Fonrich’s devices display a "recovery countdown" in the App; you can operate after the countdown ends, no need to rush unnecessarily.
Check if the reset method is correct — Some devices require "cutting off the main power first before resetting." For example, some models of Fonrich devices require first turning off the combiner box main switch, pressing the device reset button for 3 seconds, then turning the main switch back on to resume operation. A technician once failed to follow this process and couldn’t reset the device for a long time, but it worked immediately after following the correct steps.
Check for fault locking — If the device detects a persistent fault (e.g., an arc that hasn’t been eliminated), it will lock the shutdown state to prevent danger after resumption. Fonrich’s devices indicate "fault locking" via the indicator light (flashing red light). First, resolve issues such as loose module wiring or damaged insulation, then press and hold the reset button for 5 seconds to unlock and resume operation.
Fault Symptom: Without any faults (no arcs, no overloads), the rapid shutdown solar device triggers shutdown frequently—several times a day—resulting in a significant drop in power generation.
Troubleshooting Steps & Solutions:
Check if "sensitivity is set too high" — If the device’s arc detection sensitivity is set too strictly, it may trigger false shutdowns when encountering harmonic interference from the inverter or weak signals caused by poor module wiring contact. Fonrich’s devices allow sensitivity adjustment in the App, with three levels: "high/middle/low." Setting it to "middle" for residential projects and "high" for large commercial power stations usually resolves false trigger issues.
Check for surrounding interference — If there are frequency converters or high-voltage lines near the device, electromagnetic interference may cause the device to "misrecognize signals." You can replace the device’s communication cable with a shielded cable (Fonrich’s original cables come with a shielding layer to reduce interference). Additionally, keep the device at least 1 meter away from high-voltage lines.
Check the device firmware version — Older firmware versions may have bugs causing false triggers. Fonrich’s devices support OTA remote upgrades; you can update to the latest firmware in the App. A previous project had frequent false triggers, but after firmware upgrade, no further issues occurred for half a month.
Fault Symptom: After triggering shutdown, measuring the module-side voltage with a multimeter shows it drops to around 40V—failing to reach the safety standard of below 30V. Firefighters dare not approach, and the project cannot pass acceptance.
Troubleshooting Steps & Solutions:
Check the "number of parallel strings" — If multiple strings of modules are connected in parallel to one rapid shutdown solar device, a faulty shutdown module in one string will prevent the overall voltage from dropping. You can disconnect each string one by one for testing to find the non-shutting-down string and replace the corresponding module. Fonrich’s module-level shutdown devices can measure the voltage of each individual panel separately, allowing you to identify which panel fails to lower voltage at a glance without disassembling each string.
Check the wiring sequence — If the positive and negative poles are reversed, the device cannot cut off the voltage normally. Fonrich’s devices have an anti-reverse connection design that prevents incorrect insertion, but some older models lack this feature. You need to use a multimeter to check the positive and negative poles and reconnect them correctly.
Check device power matching — If the device’s rated current is smaller than the actual current of the modules, it cannot "pull down" the voltage during shutdown, failing to reach the safe level. For example, a 20A device connected to 30A modules needs to be replaced with a 32A model. Fonrich’s selection manual includes a detailed current matching table; following the manual ensures correct selection.
Today’s rapid shutdown solar devices all have fault diagnostic functions—don’t rely solely on a multimeter for blind testing:
Fonrich’s devices have a "fault self-test" option in the App. Tapping it can identify whether the issue is with power supply, communication, or the module, and also provide solutions.
The on-site device’s indicator lights can also serve as a "diagnostic tool": a blinking green light means normal, a steady red light indicates a power supply problem, and a blinking red light signals fault locking. Memorizing the meaning of these lights can double troubleshooting speed.
Q: When a rapid shutdown solar device malfunctions, can we bypass the device to resume power generation temporarily to avoid losses?
A: Not recommended! Bypassing the device will leave the module side with high voltage, posing safety hazards. In case of an emergency requiring temporary resumption, first turn off the combiner box main switch, contact the manufacturer’s technical support for remote troubleshooting guidance. Fonrich’s technical team typically responds within 10 minutes, and most faults can be resolved remotely without waiting for on-site service.
Q: A device that has been used for 3 years has frequent faults recently—should we repair it or replace it directly?
A: First, determine the type of fault: minor issues like power supply or communication problems can be repaired; if the shutdown module is faulty or firmware upgrades cannot resolve false triggers, replacing it with a new model is recommended. Fonrich’s devices come with a 25-year warranty; faulty modules can be replaced for free within the warranty period. Even beyond the warranty, there are cost-effective repair plans, which are more economical than buying a new device.
Q: Devices are prone to faults in low winter temperatures—are there any preventive measures?
A: Low temperatures can affect the device’s power supply and communication. Take these two preventive steps in advance: ① Wrap the device’s terminals with insulation cotton to prevent poor contact due to freezing; ② Conduct a comprehensive self-test on the device via the App before winter and upgrade to low-temperature-resistant firmware (Fonrich releases winter-specific firmware annually). These measures can reduce low-temperature-related faults by 80%.
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