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SolarEdge•Unknown

Analysis by Marcus & Team

SolarEdge Hybrid Inverter Error 18x72: Temperature Sensor Failure

Troubleshoot SolarEdge Error 18x72. Diagnose temperature sensor issues in your residential hybrid inverter. Follow safety procedures and NEC guidelines.

Frequently Asked Questions

•What tools are required to diagnose Error 18x72?

A calibrated multimeter, clamp meter, IR thermometer, and basic hand tools (screwdrivers, wire strippers).

•Is Error 18x72 covered under warranty?

Refer to the SolarEdge warranty documentation. Sensor failures may be covered under the inverter's or battery's warranty, depending on the terms and conditions.

•Can I replace the temperature sensor myself?

It is strongly recommended to hire a qualified electrician to replace the temperature sensor due to the high DC voltages and arc flash hazards involved. Replacing the sensor yourself could void the warranty and pose a safety risk.

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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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Technical Recommendation:

Use the SolarEdge monitoring portal or app to check the real-time temperature readings from all sensors. Compare the reading from sensor 1 to the readings from other sensors. A significant difference suggests a sensor malfunction. Alternatively, access the inverter's service menu (refer to the system manual for the key sequence) to view raw sensor data and run diagnostic tests.

Safety Warning:

Solar PV systems operate at high DC voltages (up to 600V or more). Improper handling can result in serious injury or death. Always follow NEC guidelines and manufacturer procedures for safe operation. Qualified electricians with experience in PV system maintenance must perform all repairs. Arc flash hazards exist during switching and disconnection. Use appropriate personal protective equipment (PPE), including arc-rated clothing and gloves.

Solution:

1

De-energize the PV system: Follow NEC 690 guidelines and manufacturer procedures for DC disconnect. Verify zero voltage with a calibrated multimeter.
2

Visually inspect the sensor and wiring: Check for physical damage, corrosion, or loose connections. Pay close attention to connectors.
3

Measure sensor resistance: Disconnect the sensor and measure its resistance using a multimeter. Compare the reading to the manufacturer's specifications. An open circuit indicates a broken sensor.
4

Check wiring continuity: Use a multimeter to verify continuity between the sensor and the inverter's control board. Look for shorts or open circuits.
5

Examine the inverter PCB: Inspect the area around the sensor input for signs of overheating, component damage, or loose solder joints. (Requires advanced skills and specialized tools).
6

Replace the defective sensor: Use an original equipment manufacturer (OEM) replacement part with the correct specifications. Ensure proper polarity and secure connections.
7

Power up the system and monitor: After replacing the sensor, re-energize the PV system and monitor the inverter's operation. Clear the error code and verify that the temperature readings are within the normal range.

Common Causes:

Defective temperature sensor: Sensor failure due to age, thermal stress, or manufacturing defect.
Wiring issue: Loose connection, corrosion, or broken wire in the sensor circuit.
Connector problem: Poor contact or contamination at the sensor connector.
Inverter board fault: Failure of the analog-to-digital converter (ADC) or signal processing circuitry associated with the sensor input on the main inverter PCB.
External environmental factors: Extreme temperature swings exceeding the sensor's operating range can cause temporary errors.
Battery Management System (BMS) error: If the sensor is associated with battery monitoring, the BMS may be misinterpreting the data.

Symptoms:

SolarEdge hybrid inverter displays Error 18x72, indicating a fault with temperature sensor 1. Inverter may derate power output or shut down completely. Monitoring portal or app shows abnormal temperature readings or sensor malfunction.

Technical Background:

The SolarEdge hybrid inverter integrates PV power conversion with battery management. Temperature sensors monitor critical components (e.g., DC bus capacitors, inductors, battery terminals) to prevent overheating and ensure safe operation. The inverter's control system uses temperature data for thermal management, derating, and fault protection. Sensor 1 refers to a specific sensor within the inverter or battery system. Error 18x72 indicates an open or short circuit, or an out-of-range reading from that sensor. The inverter implements anti-islanding protection per IEEE 1547 and UL 1741 standards.

Preventative Care:

Regular visual inspections: Check for loose connections, corrosion, and physical damage to the sensor and wiring.
Firmware updates: Keep the inverter's firmware up to date to ensure proper sensor calibration and fault detection.
Thermal monitoring: Use an infrared (IR) thermometer to monitor the temperature of critical components and identify potential hotspots.
Environmental control: Ensure adequate ventilation around the inverter to prevent overheating.