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Generac•SnapRS

Analysis by Marcus & Team

Generac SnapRS Sizzling Sound

Troubleshoot sizzling sounds from a Generac SnapRS rapid shutdown device. Diagnose potential causes and solutions for safe operation and NEC compliance.

Frequently Asked Questions

•What is the DC voltage level at which the rapid shutdown is initiated?

The SnapRS is designed to reduce the PV array voltage to below 30V within 30 seconds of rapid shutdown initiation, as per NEC requirements.

•How often should I inspect my SnapRS units?

Visually inspect the SnapRS units at least annually for any signs of physical damage, water ingress, or corrosion.

•What type of PPE (personal protective equipment) should I wear when working with PV systems?

Wear appropriate PPE, including insulated gloves, safety glasses, and arc-rated clothing, when working with PV systems.

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Marcus leads the technical research department at Storage Faults. Together with a team of systems analysts, he specializes in translating complex solar storage error codes into actionable diagnostic steps for the US market.

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Critical Safety Precautions:

High DC voltage is present in PV systems. Improper handling can result in severe electric shock or arc flash. Only qualified electricians should perform diagnostic and repair work on PV systems. Always verify that the system is de-energized and locked out before beginning any work. Wear appropriate personal protective equipment (PPE), including insulated gloves and safety glasses. Follow NEC guidelines for safe work practices. Rapid shutdown activation may not completely eliminate all DC hazards.

Common Causes:

Internal component failure within the SnapRS unit (e.g., capacitor, MOSFET) leading to arcing.
Water ingress into the SnapRS housing, causing short circuits and corrosion.
Loose wiring connections at the SnapRS input or output terminals, resulting in resistive heating and arcing.
Overvoltage stress due to lightning surges or grid transients exceeding the SnapRS voltage rating.
Manufacturing defect in the SnapRS unit.
Degradation of internal insulation leading to partial discharge.

Observed Symptoms:

A distinct sizzling sound emanating from a Generac SnapRS rapid shutdown device, suggestive of electrical arcing or component failure. This noise occurs during daylight hours when the PV array is actively producing power.

Step-by-Step Fix:

1

Immediately disconnect the AC power to the Generac inverter and engage the PV system DC disconnect. Verify voltage is below 30V using a calibrated multimeter.
2

Visually inspect the SnapRS unit for any signs of physical damage, water ingress, or corrosion.
3

Using a calibrated multimeter, measure the voltage at the input and output terminals of the SnapRS unit after disconnecting the PV module. Compare these readings to the expected open-circuit voltage (Voc) of the PV module under normal operating conditions. If output voltage does not correspond to expected reduced levels, the unit is faulty.
4

Use a calibrated clamp meter to measure the current flowing through the PV string. Check for any abnormal current fluctuations.
5

Check resistance between ground and the PV array, per NEC 690.5(C). High resistance may indicate a ground fault.
6

Replace the faulty SnapRS unit with a new, approved replacement. Ensure the replacement is installed according to the manufacturer's instructions and NEC guidelines. Torque connections to spec.
7

After replacement, re-energize the PV system and monitor the SnapRS unit for proper operation. Use the Generac monitoring app to verify communication and functionality. Document all voltage and current measurements.

Technical Background:

The Generac SnapRS is a module-level rapid shutdown device (MLPE) designed to reduce PV array voltage to safe levels (<30V) upon initiation of rapid shutdown, as per NEC 2017/2020 requirements. It communicates with the inverter to disconnect the PV module from the string. The device contains electronic components that can fail due to overvoltage, overcurrent, thermal stress, or water ingress. The sizzling sound indicates possible partial discharge within the device.

Preventative Care:

Regularly inspect SnapRS units for physical damage or corrosion, at least annually.
Ensure proper sealing of SnapRS housings to prevent water ingress.
Conduct routine insulation resistance testing of the PV array to identify potential ground faults.
Perform thermal imaging scans of SnapRS units to detect hotspots indicative of component failure. Record and compare temperatures over time. Replace units showing increased thermal signature.
Keep SnapRS firmware updated.