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When your inverter shows persistent error codes that others can't fix, we step in. Our specialized repair techniques resolve the most challenging inverter faults - from ground isolation errors to DC injection problems. Check our comprehensive list of successfully repaired error conditions.

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Photovoltaic Inverter Repair & Diagnostics

In-depth diagnostics of inverter failures — including internal explosions, burnt PCBs, and severe hardware faults
Root-cause analysis using oscilloscopes, logic analyzers, and load simulations
Detection and elimination of software-related faults: EEPROM corruption, firmware bugs, and error code resolution
Repair of MPPT modules, power stages, gate drivers, and signal path anomalies
Troubleshooting of grid synchronization, DC link stability, and AC waveform distortion
Detailed failure reports, waveform captures, and high-resolution photos of defective areas

Inverter Component Restoration & Upgrades

Replacement of IGBTs, MOSFETs, optocouplers, control ICs, and passive components
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Rebuilding of cooling systems: fan units, thermal paste, and heat sink realignment
Reinforcement against future failures: conformal coating, transient suppression modules, and enhanced insulation paths
Optional firmware optimization for extended inverter lifespan and better grid behavior
Includes post-repair testing, load simulation, and full technical documentation with results

Advanced Inverter Diagnostics

Complete diagnostics using professional Fluke and Tektronix equipment
Electrical parameter analysis with 0.1% precision accuracy
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Insulation and grounding testing according to VDE standards
Detailed report with photographic documentation of all problem areas

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Factory firmware restoration for all inverter brands
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Circuit trace restoration using micro-soldering techniques
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Final Quality Testing

Complete safety function verification
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Quality certificate with comprehensive test protocols

List of errors on the inverter Mastervolt

By Erik Zaikin

5 min read

*Fast blink = 2 blinks per second, slow blink = 1 blink per second*

**AC Not Connected:**
1. **Insufficient Irradiation**: No display during daytime.
- **Action**: Contact your installer.
2. **DC Switch in Off Position**:
- **Action**: Move DC switch to the ON position.
3. **DC Fuse Blown**:
- **Action**: Check string fuses.
4. **No PV Power (Voltage Out of Range)**: DC voltage should be between 200-1000V.
- **Action**: Check if the DC voltage is within the required range.

**Grid Faults:**
- **Red LED for AC Frequency High/Low**: Grid frequency out of range.
- **Action**: If this occurs often, contact your installer.
- **Red LED for AC Phase Jump**: Disconnect due to fast frequency fluctuations.
- **Action**: Contact your installer if frequent.
- **Red LED for AC Quality**: Disconnect due to bad grid quality.
- **Action**: If frequent, contact your installer.
- **Red LED for No Grid**: No grid available.
- **Action**: Check the fuses.
- **Red LED for AC Voltage Low/High**: Grid voltage too low or high.
- **Action**: Contact your installer if it occurs often.
- **Red LED for Transient AC Voltage High**:
- **Action**: If frequent, contact your installer.
- **Red LED for Grid Voltage High for 10 Minutes**:
- **Action**: If it happens often, contact your installer.
- **Red LED for AC Phase Balance**: Grid phase balance out of range.
- **Action**: Contact your installer if frequent.

**Hardware Faults:**
- **Red Fast Blink for Hardware Problem**:
- **Action**: Contact your installer.
- **Red LED for HW Insulation**: Insulation fault with low resistance between DC and PE.
- **Action**: Check the PE connections.
- **Red LED for High Temperature**: High internal heat sink temperature.
- **Action**: Wait for the inverter to cool down before it restarts.

**Ambient Faults:**
- **Red LED for Solar Input Over Voltage**: Solar input 1 and/or 2 over voltage (DC > 1000 V).
- **Action**: Check PV array open circuit voltage and contact your installer.
- **Red LED for Solar Low**: Solar 1 and 2 voltage low due to low irradiation.
- **Action**: Check string fuses, DC switch, DC cable, and wait till sunrise.

**Normal Operation:**
- **Red Slow Blink for Reclosure Time**: Reclosure time counting.
- **Action**: No action required; reclosure may take 5 minutes.
- **White ON for Derating**: Power reduction due to various reasons.
- **Action**: Check the fan, MasterBus power setting, and the voltages.
- **White ON for Power Management**: Power reduction by request of the grid operator.
- **Action**: No specific action required unless adjustments are needed.
- **White ON for Solar Input Low**: Solar input voltage 1 and/or 2 low but inverter is operating.
- **Action**: Check the string fuses, DC switch if applicable, DC cable; wait till sunrise.
- **White ON for Normal Operation**: Indicates the inverter is functioning normally.

**StringMaster Faults:**
- **HW Error**: Refer to the StringMaster manual for troubleshooting.
- **Not Connected**: StringMaster has no connection to MasterBus.
- **Action**: Check MasterBus cabling and configuration.
- **Warning**: Refer to the manual for warning descriptions.
- **OC (Over Current)**: Installation error.
- **Action**: Check cabling and scheme.
- **NEG (Reverse Polarization)**:
- **Action**: Check string polarization.
- **LOW Performance**: Current low due to possible issues like shadows.
- **Action**: Check fuse, cabling, irradiation of PV modules.
- **OVP 1 (2) Over Voltage Protection**: On Input 1 or 2.
- **Action**: Check Input 1 or 2 varistor.

### TROUBLESHOOTING

If the problem cannot be resolved using the table below, consult an installer.

**Error LED - Error Code - Meaning - What to do?**

- **Off - NONE** - No error - Nothing; the inverter is operating normally.
- **Off - Insufficient Irradiation** - Nothing. PV module irradiation is insufficient (e.g., at night).
- **Off - No Power from PV Modules** - Consult an installer if the display shows no information during the day. The wiring between the PV modules and the SunMaster might be faulty.
- **Off - WAIT 0:00** - Startup - Nothing. After the SunMaster is (re)connected to the AC network, it checks the network quality before starting normal operation. It may take up to 5 minutes.
- **Off - SOL1 LOW** - Solar input voltage is low - Nothing; normal situation at dawn and dusk. Consult an installer if the problem persists even when PV module irradiation is sufficient.
- **Off - COUNTRY (Flashing Text)** or any country name - A country code has not yet been selected - Select the desired country code (see section 5.3.1).
- **With - TEMP HIGH** - The inverter's internal temperature is high - The air flow of the SunMaster might be obstructed. See Chapter 3.3 for installation instructions. If the problem persists, consult an installer.
- **With - SOL HIGH** - Solar input voltage is high - Contact the supplier.
- **With - NO GRID** - There is no AC network connection - Check the AC network connection. Check the fuse in the meter cabinet.
- **With - UAC LOW** - AC voltage low - The AC network voltage is too low. Consult an installer.
- **With - UAC HIGH** - AC voltage high - The AC network voltage is too high. Consult an installer.
- **With - FAC LOW** - AC frequency low - The AC network frequency is too low. Consult an installer.
- **With - FAC HIGH** - AC frequency high - The AC network frequency is too high. Consult an installer.
- **With - INSULATION** - Insulation failure, leakage current between PV modules and the ground - Consult an installer.
- **With - DC INJECT** - Grid fault, the inverter has detected a fault in the network connection - Consult an installer if the problem persists.
- **With - G QUALITY** - Grid quality fault, the inverter is operating on an unstable network.
- **With - RC PROTECT** - Grid fault, the RCD has detected a fault current.
- **With - ISLANDING** - Anti-Islanding, the inverter has detected an islanding situation.
- **With - BUS VOLT** - Inverter protection, the inverter returns to normal operation mode.
- **With - OCTP** - Network fault, Output protection. The inverter returns to normal service mode.
- **With - OCP** - Network fault, Output protection. The inverter returns to normal service mode.
- **With - OOCP** - Network fault, Output protection. The inverter returns to normal service mode.
- **With - PV OCP** - PV fault, Input protection. The inverter returns to normal service mode.
- **With - PV OCTP** - PV fault, Input protection. The inverter returns to normal service mode.
- **Fast Blinking - NTC FAIL** - Defective device - Note the exact error text. Consult an installer for SunMaster replacement.
- **Fast Blinking - RCMU FAIL** - In the SunMaster, so that it can be replaced.

Models: SUNMASTER Sun Master
ES2.2TL ES3.0TL ES3.6TL ES4,6TL ES5.0TL
IS10 IS15
CS10TL CS12.5TL CS15TL CS20TL CS30TL
XL10K XL15K
XS4300 XS3200 XS2000 XS6500
SOLADIN 1000 1500 I000 I500 600
2200 3000
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