Solar Inverter Error Codes & Troubleshooting Guide

🔍 What Is Happening?

The inverter is powered by DC solar panels but cannot detect utility AC grid power at its output terminals. Generation halts because grid-tied inverters must safely shut down when the grid is dead (anti-islanding protection).

⚙️ Common Root Causes

• Local DISCOM electricity power cut / load shedding.
• The AC Miniature Circuit Breaker (MCB) in the AC Distribution Box (ACDB) tripped or is turned OFF.
• Blown AC backup fuse or loose AC cable connection at the inverter bottom terminal.

✅ Safe DIY Checks for Owners

• Check if your house or surrounding neighborhood has mains power from the grid.
• Inspect the ACDB box near the inverter: verify whether the solar AC MCB switch is flipped down (OFF). If tripped, flip it up (ON) once.
• Wait 5 minutes after grid restoration for the inverter's 300-second synchronization countdown to finish.

🛠️ Technician / Engineering Fix

Measure AC voltage between Phase and Neutral at the inverter AC connector terminals with a true-RMS multimeter. If grid voltage is present (220–240V) but Warning 201 persists, inspect the internal AC output contactor relay.

🔍 What Is Happening?

The AC grid voltage exceeds the inverter's upper safety limit (typically > 253V to 260V in India). The inverter disconnects or curtails power to prevent damaging connected household appliances.

⚙️ Common Root Causes

• Midday grid overvoltage caused by high localized solar feed-in on the neighborhood transformer.
• High line impedance due to thin AC output cables or long cable runs from inverter to main LT panel.
• Loose neutral wire connection in the ACDB or main meter box.

✅ Safe DIY Checks for Owners

• Check if the tripping happens primarily between 11:30 AM and 2:30 PM on sunny days.
• Inspect inverter screen to check the live Vac reading (e.g., 255V or 260V).
• Turn on heavy household loads (such as an air conditioner or water pump) to see if local consumption pulls the voltage down.

🛠️ Technician / Engineering Fix

Measure voltage drop across the AC run under full solar export. If cable loss is > 1.5%, upgrade cable cross-section (e.g. from 4 sq. mm to 6 sq. mm). Adjust DISCOM overvoltage grid parameters if permitted under local CEA/DISCOM interconnection norms.

🔍 What Is Happening?

The inverter detected that the electrical insulation resistance between the DC solar array (positive or negative conductors) and the earth grounding is below the minimum safety threshold (< 50 kΩ). This indicates electrical leakage to ground.

⚙️ Common Root Causes

• Water ingress inside DC combiner boxes, MC4 cable connectors, or module junction boxes after rain or washing.
• Damaged DC cable insulation scraped against sharp edges of the galvanized iron mounting structure.
• Cracked module glass, delaminated backsheet, or rodent damage to rooftop solar cabling.

✅ Safe DIY Checks for Owners

• Check if the error clears once the morning dew evaporates or after modules dry following a wash.
• Visually inspect rooftop DC cables from a safe distance for sagging wires touching the roof or ponded water.
• ⚠️ DO NOT touch live DC wires, module frames, or mounting structures with bare hands when this error is active.

🛠️ Technician / Engineering Fix

Perform an insulation resistance (Megger) test at 1,000V DC on each individual PV string disconnected from the inverter. Isolate the faulty string, locate the pinched cable or compromised MC4 connector, repair with UV-rated double-insulated solar cable, and re-test.

🔍 What Is Happening?

The inverter's internal dual-microcontroller system detected conflicting voltage or current measurement readings between the master DSP and the redundant slave safety monitoring circuit.

⚙️ Common Root Causes

• Transient electronic glitch caused by external grid voltage spikes or nearby lightning surge.
• Drift or failure in internal Hall-effect current sensors or voltage divider resistors.
• Outdated firmware requiring recalibration.

✅ Safe DIY Checks for Owners

• Perform a full safe power cycle: 1) Switch OFF the AC breaker, 2) Turn OFF the DC rotary isolator switch under the inverter, 3) Wait 10 minutes until all LED lights and screen completely turn dark, 4) Turn ON DC switch, 5) Switch ON AC breaker.
• If the error disappears, it was a transient anomaly.

🛠️ Technician / Engineering Fix

If Error 102 reappears immediately after power cycle, connect Growatt ShineTools software via USB/Wi-Fi to audit internal sensor calibration offsets. If calibration fails, coordinate an inverter control board replacement or OEM warranty claim.

🔍 What Is Happening?

The internal direct current (DC) bus capacitor voltage exceeded the maximum safety limit. The inverter locks out immediately to prevent capacitor explosion and internal power bridge damage.

⚙️ Common Root Causes

• PV array open-circuit voltage (Voc) too high during cold winter mornings with high irradiance.
• Faulty DC boost circuit or short-circuited boost MOSFET inside the inverter.
• Sudden AC grid disconnection during peak generation causing DC bus charge spike.

✅ Safe DIY Checks for Owners

• Check if error occurred in winter morning on a cold sunny day.
• Turn off the system and wait 15 minutes before attempting a single restart.
• ⚠️ If the error repeats immediately, do NOT keep restarting. Leave the system OFF.

🛠️ Technician / Engineering Fix

Measure DC string open-circuit voltage (Voc) at the DC isolator with a 1,000V DC multimeter. Calculate temperature-corrected Voc (-0.3%/°C). If Voc exceeds inverter Vmax (e.g. 550V or 1,000V), split strings. If Voc is normal, replace internal boost stage board.

🔍 What Is Happening?

The inverter's internal electromechanical AC grid disconnection relay failed its startup self-test. The relay contacts may be welded together or failing to close securely.

⚙️ Common Root Causes

• Frequent grid fluctuations causing mechanical relay wear over several years.
• Contact pitting or welding caused by severe grid voltage transients.
• Defective relay driver circuit on the inverter motherboard.

✅ Safe DIY Checks for Owners

• Perform a full power cycle (AC OFF -> DC OFF -> Wait 10 min -> DC ON -> AC ON).
• Listen closely for an audible 'click' sound inside the inverter 30–60 seconds after power-on. Absence of a click confirms relay failure.

🛠️ Technician / Engineering Fix

Perform continuity check across relay terminals under unpowered conditions. If contacts are welded closed (zero resistance when unpowered), the relay board must be repaired or replaced under Growatt warranty.

🔍 What Is Happening?

Internal power transistor (IGBT) heat sink temperature exceeded the maximum thermal limit (typically > 85°C). The inverter either curtails generation power or shuts down completely until it cools down.

⚙️ Common Root Causes

• Inverter installed in direct sunlight without a sunshade canopy.
• Dust and spider webs clogging the rear heat-sink cooling fins.
• External cooling fan failed or blocked by foreign objects.

✅ Safe DIY Checks for Owners

• Check if the inverter is exposed to direct afternoon sun. If hot to touch, erect a protective shade canopy above it.
• Inspect the aluminum fins behind the inverter for heavy dust or insect nests. Clean gently with a soft dry brush.

🛠️ Technician / Engineering Fix

Inspect cooling fan tachometer signals and thermal sensor calibration. Ensure minimum installation clearances (300 mm left/right, 500 mm top) are respected for natural convection.

🔍 What Is Happening?

The Solis inverter has detected that AC mains grid power is completely absent from its AC terminal. As a safety protocol, it ceases export immediately.

⚙️ Common Root Causes

• Local DISCOM power cut or grid maintenance shutdown.
• Tripped AC miniature circuit breaker (MCB) or residual current breaker (RCCB) in the ACDB.
• Loose screw terminal on the AC connection plug at the bottom of the inverter.

✅ Safe DIY Checks for Owners

• Verify whether other appliances in the property have electricity.
• Open the ACDB box and verify that all breaker switches are in the UP (ON) position.
• Wait for grid power to return; Solis inverters resume generation automatically within 3 to 5 minutes.

🛠️ Technician / Engineering Fix

Check for Phase-Neutral and Phase-Earth voltages at the inverter AC plug. If 230V is present but Fault 01 continues, test AC sensing optocouplers on the main control board.

🔍 What Is Happening?

The AC grid voltage has crossed the programmed upper limit (typically 253V for India). The Solis inverter disconnects to prevent equipment degradation.

⚙️ Common Root Causes

• High local grid voltage on the utility distribution transformer during sunny midday hours.
• Undersized AC cabling between the inverter and the electricity meter box resulting in high voltage drop.
• Poor grid neutral connection in the distribution network.

✅ Safe DIY Checks for Owners

• Check the Solis LCD screen by pressing Enter -> Information -> Grid V. Note the recorded voltage.
• Determine if the fault occurs primarily between 12:00 PM and 3:00 PM when solar production is at peak.
• Run household loads (AC, washing machine) to absorb surplus power locally.

🛠️ Technician / Engineering Fix

Perform line impedance test. If AC cable size is inadequate, upgrade wiring. Consult local electricity distribution company (DISCOM) to lower transformer tap setting if local baseline grid voltage is consistently > 250V.

🔍 What Is Happening?

Solis PV isolation protection triggered because DC insulation resistance to earth is below 100 kΩ. High risk of electrical leakage or short-circuit to metal mounting structures.

⚙️ Common Root Causes

• Rainwater or morning condensation entering unsealed MC4 connectors on the roof.
• Damaged solar cable insulation pinched beneath panels or aluminum clamps.
• Degraded backsheet on older solar modules allowing moisture penetration.

✅ Safe DIY Checks for Owners

• Check if the fault triggers in the morning when dew is heavy, but clears around 11:00 AM.
• ⚠️ DO NOT attempt to inspect rooftop cables with bare hands or during rainy weather.
• Power cycle the inverter once on a dry sunny afternoon to confirm if the fault is persistent.

🛠️ Technician / Engineering Fix

Disconnect all strings from the DC isolator. Use an insulation resistance tester (Megger at 1,000V DC) between PV(+) and Earth, and PV(-) and Earth on each string. Isolate and replace the damaged module or reseal MC4 connectors with IP68 junction kits.

🔍 What Is Happening?

The inverter's internal Ground Fault Current Interrupter (GFCI) detected an active leakage current to ground exceeding 30mA. This is an urgent safety trip to prevent electrical shocks.

⚙️ Common Root Causes

• Active current leak between solar panel frame and live electrical cables.
• Damaged earthing pit or severed equipment grounding cable.
• Inverter internal filter capacitor breakdown.

✅ Safe DIY Checks for Owners

• Keep away from metal solar structure. Do not touch bare metal frames.
• Turn off the AC breaker and DC switch. Contact a certified technician immediately.

🛠️ Technician / Engineering Fix

Perform earth loop impedance and residual current testing with an RCD tester. Verify earth pit resistance is strictly under 5 Ohms. Repair any short-circuit between PV conductors and structure.

🔍 What Is Happening?

The internal heatsink or ambient temperature sensor registered temperature above safe operating parameters. The inverter pauses or reduces output to prevent thermal breakdown.

⚙️ Common Root Causes

• Direct sunlight hitting the inverter enclosure without shelter.
• Cooling heatsink clogged with dust, cobwebs, or construction debris.
• Inadequate ventilation clearance around the inverter casing.

✅ Safe DIY Checks for Owners

• Check if the inverter is located in an enclosed, unventilated room or directly exposed to the afternoon sun.
• Clean cooling ribs on the back and sides of the unit using a soft dry brush.

🛠️ Technician / Engineering Fix

Verify thermal paste contact between internal power module and heatsink. Install sunshade canopy or auxiliary ventilation fan if ambient temperature routinely exceeds 45°C.

🔍 What Is Happening?

The AC grid voltage at the Sungrow inverter terminal is higher than the protection parameter setpoint. The inverter enters standby mode until grid voltage drops.

⚙️ Common Root Causes

• Overvoltage on utility grid during peak midday hours.
• High grid impedance or excessively thin AC cabling creating voltage drop.
• Loose terminal connection in the AC distribution box.

✅ Safe DIY Checks for Owners

• Check inverter LCD display or iSolarCloud app for the live Phase voltage.
• Notice if the fault occurs primarily during bright midday hours and clears in late afternoon.

🛠️ Technician / Engineering Fix

Check grid voltage and impedance. Adjust inverter grid overvoltage protection limits via iSolarCloud advanced installer settings if approved by local DISCOM regulations.

🔍 What Is Happening?

Sungrow inverter detected zero voltage on the AC grid connection. The inverter stops feeding power into the lines to prevent electrocuting utility repair workers.

⚙️ Common Root Causes

• DISCOM utility power cut or grid trip.
• AC circuit breaker or isolator switch turned off.
• Blown fuse inside the AC distribution box.

✅ Safe DIY Checks for Owners

• Check if premises have mains power from the grid.
• Check AC circuit breaker in the ACDB near the inverter.

🛠️ Technician / Engineering Fix

Check AC terminal connection and verify Phase, Neutral, and Earth voltages with true-RMS meter.

🔍 What Is Happening?

The measured insulation resistance between the DC solar array and ground is below the safety threshold. The Sungrow inverter halts generation and illuminates the red alarm LED.

⚙️ Common Root Causes

• Moisture or water ingress in DC cable connectors, junction boxes, or module backsheets.
• Damaged cable insulation in the DC string wiring.
• Incorrect grounding configuration of the mounting structure.

✅ Safe DIY Checks for Owners

• Notice if fault appears in early morning and disappears once modules warm up in the sun.
• ⚠️ Do not climb on wet roof or touch live solar modules when fault 039 is indicated.

🛠️ Technician / Engineering Fix

Perform insulation resistance test with 1,000V Megger on disconnected strings. Locate the cable ground fault, replace damaged wire section, and verify earth pit resistance.

🔍 What Is Happening?

The Sungrow inverter detected that its protective earth (PE) grounding conductor is completely disconnected or has abnormally high resistance. Generation is halted for human safety.

⚙️ Common Root Causes

• Loose or disconnected earth wire at the inverter casing grounding lug.
• Dry, corroded, or damaged chemical earth pit in the ground.
• Broken copper or GI earthing strip between roof and ground pit.

✅ Safe DIY Checks for Owners

• Inspect the green/yellow earthing cable connected to the bottom exterior lug of the inverter casing to see if it has come loose.

🛠️ Technician / Engineering Fix

Measure earth pit resistance with a calibrated 4-terminal Earth Tester. Re-torque PE cable lugs and perform earth pit moisture/chemical replenishment if resistance is > 5 Ohms.

🔍 What Is Happening?

The inverter's Arc Fault Circuit Interrupter (AFCI) detected a dangerous electrical DC arc in the solar string. DC arcing creates extreme localized heat (> 3,000°C) and represents an immediate fire risk.

⚙️ Common Root Causes

• Loose or improperly crimped MC4 cable connector in the string.
• Corroded DC fuse or loose terminal screw in the DC distribution box.
• Damaged or broken solar panel internal ribbon connection.

✅ Safe DIY Checks for Owners

• ⚠️ DO NOT attempt to clear this fault or restart the system without inspection.
• Turn off the AC breaker and leave the inverter OFF until a certified solar technician inspects the plant.

🛠️ Technician / Engineering Fix

Perform thermal imaging (thermography) and string loop impedance tests on every DC connector and fuse block. Re-crimp loose MC4 connectors with certified solar crimping tools. Reset AFCI via iSolarCloud app after verified repair.

🔍 What Is Happening?

GoodWe inverter cannot detect AC grid voltage. System stops power export to comply with safety anti-islanding regulations.

⚙️ Common Root Causes

• Utility grid power outage / DISCOM cut.
• AC circuit breaker in ACDB box tripped.
• AC cable loose at GoodWe output connector.

✅ Safe DIY Checks for Owners

• Check if main property has electricity from the grid.
• Verify that the AC breaker dedicated to the solar plant is switched ON.

🛠️ Technician / Engineering Fix

Measure AC voltage between Phase and Neutral at inverter connector terminals. Verify AC breaker sizing and contact integrity.

🔍 What Is Happening?

AC grid voltage is out of allowable operating limits (Vac High or Vac Low).

⚙️ Common Root Causes

• Midday voltage surge on local grid transformer.
• High resistance / undersized AC output cable run.
• Loose Neutral connection.

✅ Safe DIY Checks for Owners

• Check live Vac on GoodWe LCD screen or SEMS portal app.
• Confirm if fault coincides with peak sunshine hours.

🛠️ Technician / Engineering Fix

Test line resistance from inverter to meter. Upgrade AC cable gauge or liaise with DISCOM for voltage tap stabilization.

🔍 What Is Happening?

GoodWe inverter detected that insulation resistance between DC solar array and ground is below safe limits (< 100 kΩ).

⚙️ Common Root Causes

• Moisture ingress in rooftop MC4 connectors or module junction box.
• Scraped DC cable jacket touching metal frame.
• Cracked solar panel glass allowing water infiltration.

✅ Safe DIY Checks for Owners

• Observe if error clears as midday sun dries moisture off modules.
• ⚠️ Do not touch rooftop metal structure or cables during this error.

🛠️ Technician / Engineering Fix

Perform 1,000V DC insulation resistance testing across each string with a Megger. Locate fault, re-terminate connectors, and seal with IP68 waterproof boots.

🔍 What Is Happening?

Residual leakage current to earth exceeded the maximum safety limit. Immediate shutdown to prevent shock and electrical fire hazards.

⚙️ Common Root Causes

• Direct short circuit between DC conductor and grounded structure.
• Severed or floating earth ground cable.
• Damaged internal RCD sensor inside the inverter.

✅ Safe DIY Checks for Owners

• Turn off the AC breaker and DC switch. Contact certified technician.

🛠️ Technician / Engineering Fix

Perform earth resistance test and residual current measurement. Isolate degraded string or faulty inverter hardware.

🔍 What Is Happening?

DC open-circuit voltage (Voc) from the solar panels exceeds the maximum permissible DC input voltage rating of the GoodWe inverter.

⚙️ Common Root Causes

• Too many solar modules connected in series in a single string.
• Cold weather causing solar module open-circuit voltage (Voc) to spike above design limits.

✅ Safe DIY Checks for Owners

• Turn OFF the DC switch immediately to protect inverter internal capacitors from overvoltage breakdown.

🛠️ Technician / Engineering Fix

Measure DC string open-circuit voltage with 1,000V DC meter. Re-string modules into two shorter strings to keep Voc safely below maximum inverter rating under winter temperature coefficients.

🔍 What Is Happening?

The inverter's internal temperature has exceeded safety operating thresholds.

⚙️ Common Root Causes

• Inverter installed in direct sunlight or poorly ventilated location.
• Blocked cooling fins or clogged external fan.

✅ Safe DIY Checks for Owners

• Check if inverter is shaded. Clear any debris or dust from the cooling heatsink on the back of the inverter.

🛠️ Technician / Engineering Fix

Verify external cooling fan operation, thermal sensor accuracy, and install sun protection awning.