SMA Event 3501 Insulation Resistance Check During Rain –... | solarfaults.org

Technical Background:

The SMA Event 3501 inverter employs insulation resistance monitoring to detect potential ground faults. When moisture infiltrates the electrical components, it can lower the insulation resistance (RISO) below acceptable levels, prompting the inverter to shut down to prevent electrical hazards. The inverter continuously checks for ground faults as per NEC requirements, ensuring safe operation within defined parameters.

Symptoms:

Homeowners may observe the inverter's LED indicators flashing irregularly or displaying error codes on the monitoring app, indicating a drop in production or an alarm condition. Production data may show unexpected dips, particularly during rain events.

Possible Causes:

Moisture ingress into the inverter or junction box, leading to insulation resistance drop.
Damaged or degraded insulation on DC wiring, particularly in exposed areas.
Faulty or corroded connections at the array, junction box, or inverter terminals.
Ground faults due to water pooling or improper drainage around the system site.
Internal inverter failure triggered by environmental conditions, such as excessive humidity.
Improper grounding practices that compromise system integrity.

Solution:

1

Disconnect the inverter from the utility grid and isolate the array by using an MC4 disconnect tool.
2

Use a digital insulation resistance tester to measure RISO across the DC terminals of the inverter, ensuring readings are above NEC minimums (typically 1 MΩ).
3

Inspect all DC wiring and connections for signs of damage, corrosion, or moisture ingress.
4

Verify the integrity of the junction box and ensure all seals are intact to prevent water entry.
5

If insulation resistance is low, replace damaged cables or components as necessary.
6

Reconnect the system and monitor performance using the inverter’s monitoring app to ensure fault codes are cleared.
7

Document all findings and repairs for future reference and compliance.

Safety Warning:

Always consult a licensed electrician or certified solar installer for troubleshooting and repairs to ensure compliance with NEC standards and maintain system safety.

Prevention:

To avoid similar issues in the future, ensure proper system techniques are followed, including using weather-rated components and ensuring adequate drainage around the inverter and junction boxes. Regularly inspect the system for wear and tear, especially after severe weather events.

Frequently Asked Questions

•What should I do if insulation resistance is low?

If insulation resistance is low, inspect the wiring and connections for moisture or damage. Ensure all components are dry and functioning properly.

•How does rain affect insulation resistance checks?

Rain can introduce moisture that affects insulation resistance readings. It's crucial to perform checks in dry conditions for accurate results.

SMA Event 3501 Insulation Resistance Check During Rain – Troubleshooting & Technical Fix Guide

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Frequently Asked Questions

•What should I do if insulation resistance is low?

•How does rain affect insulation resistance checks?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention: