Solar System Tripping the Breaker: Causes and Fixes

Key Takeaways

• The most likely cause of a solar system tripping a breaker is an electrical overload or a short circuit.
• Always start by checking your inverter's display for error codes and reducing connected loads.
• Before inspecting any wiring or components, ensure all power sources (grid, solar, battery) are safely disconnected.
• If faults persist after basic troubleshooting, or if you suspect internal inverter damage, contact a qualified technician.

Why is your solar system tripping the breaker?

Your solar system trips a breaker primarily to protect itself and your home's electrical circuits from damage due to excessive current. The most common cause is an electrical overload, where the total power drawn by connected appliances exceeds the capacity of your inverter or the breaker's rating. The first thing to check is the total load currently connected to your system.

Diagnosis

Follow these steps to diagnose why your solar system is tripping its breaker:

1. Check the Inverter Display for Error Codes:

• • What to look for: Most inverters will display a specific error code or message when a fault occurs.
  • What it means: These codes directly point to the type of fault. For example, a Solis S5-EH1P-L inverter might show "Over-Load" for a load overload fault or "OV-ILLC" for LLC hardware overcurrent. An Axpert VM III or Growatt SPF ES might show "07 Overload time out" or "51 Over current or surge". Deye SG03LP1 inverters might display "F26 AC over current fault of hardware" or "F28 AC overcurrent fault". Fox ESS H1(G2)/AC1(G2) inverters can show "Over Load Fault" or "Eps Over Load". GoodWe ET Series inverters may display "Back-Up Over Load".
  • Action: Note down any codes and refer to your inverter's manual for their specific meaning and recommended actions.

2. Evaluate Connected Loads:

• • What to look for: Identify all appliances currently running on your solar system. Compare their total wattage to your inverter's rated output power.
  • What it means: If the total load exceeds your inverter's rated output power, especially during startup of inductive loads (like motors or refrigerators), it can cause an overload. For example, a Solis S5-EH1P3K-L has a Rated Output Power of 3kW, while a Solis S5-EH1P6K-L has a Rated Output Power of 6kW. An Axpert VM III 5KW model has a 5KVA/5KW rated power. Deye SG03LP1 SUN-5K-SG03LP1-EU has a rated output of 5000W. Growatt SPF 5000 ES has a 5KVA/5KW rated power. Fox ESS H1-5.0-E-G2 has a 5000W rated power. GoodWe ET Series GW5KL-ET has a 5000VA rated power. Many inverters also have a surge capacity, such as the Axpert VM III which can handle 2 times its rated power for 5 seconds, or the Solis S5-EH1P-L series which can handle 4.5 kVA to 7 kVA for 10 seconds depending on the model. However, sustained high loads or repeated surges can still trip breakers.
  • Action: Switch off non-essential appliances one by one and try resetting the breaker. If the breaker holds, you've identified an overload issue.

3. Inspect Wiring and Connections:

• • What to look for: Visually check all AC and DC wiring connections for loose terminals, frayed insulation, or signs of burning.
  • What it means: A loose connection can create resistance, leading to heat buildup and potential short circuits. A short circuit will cause a sudden, massive surge in current, immediately tripping the breaker. Axpert VM III and Growatt SPF ES inverters can display "05 Output short circuited" if a short is detected.
  • Action: Before touching any wiring, ensure all power sources (grid, solar, battery) are disconnected. Tighten any loose connections. If you find damaged wiring, it must be replaced by a qualified electrician.

4. Verify Breaker Sizing:

• • What to look for: Check the amperage rating of the tripped breaker.
  • What it means: Breakers are sized to protect the wiring and equipment. If a breaker is undersized for the inverter's output or the connected load, it will trip frequently. Conversely, an oversized breaker may not trip during a fault, leading to equipment damage or fire.
  • • For Axpert VM III inverters, recommended AC breakers are 16A for 1.5KW, 32A for 3KW, and 50A for 5KW models. A 150A fuse is provided for battery over-current protection.
    • Deye SG03LP1 models recommend a 32A or 40A AC breaker for backup loads and a 40A AC breaker for the grid connection. DC battery breakers are 100A for the SUN-3.6K-SG, 125A for the SUN-5K-SG, and 200A for the SUN-6K-SG.
    • Growatt SPF ES inverters recommend a 40A AC breaker for the SPF 3500 ES and a 50A AC breaker for the SPF 5000 ES. Recommended battery breakers are 100A / 60VDC for the SPF 3500 ES and 150A / 60VDC for the SPF 5000 ES.
    • GoodWe ET Series inverters require an external AC breaker for on-grid connection, with ratings like 25A/400V for GW5K/GW5KL-ET and GW6.5K/GW6KL-ET models, and 32A/400V for GW8K/GW8KL-ET and GW10K/GW10KL-ET models.
    • Fox ESS H1(G2)/AC1(G2) inverters require a micro-breaker for max output overcurrent protection device between the inverter and grid, rated 50A for 3.0/3.7kW models and 63A for 4.6/5.0/6.0kW models.
    • Solis S5-EH1P-L inverters require a battery switch with a rated current of ≥ 80A for 3K~3.6K Models and ≥ 125A for 4.6K~6K Models.
  • Action: Consult your inverter manual and a qualified electrician to ensure all breakers (AC and DC) are correctly sized for your system and local electrical codes.

5. Check Grid Stability (for grid-tied systems):

• • What to look for: Inverter error codes related to grid voltage or frequency.
  • What it means: Fluctuations in the utility grid can cause your inverter to disconnect for safety, which might manifest as a tripped breaker. Solis S5-EH1P-L inverters can report "OV-G-F01" (Grid frequency exceeds upper range) or "OV-G-V01" (Grid voltage exceeds upper range). Deye SG03LP1 inverters might show "F53 AC line low voltage" or "F56 AC over voltage". GoodWe ET Series can display "VAC Failure" or "FAC Failure". Fox ESS H1(G2)/AC1(G2) inverters may show "Grid Volt Fault" or "Grid Freq Fault".
  • Action: If grid faults are indicated, confirm whether the power grid is abnormal. Ensure the AC cable is properly connected. If the grid is unstable, the inverter may resume operation once grid conditions stabilize.

Cause/fix table section

Inverter and Load-Side Checks

When a breaker trips, the issue can originate from either the inverter itself, the loads connected to it, or the grid connection.

Inverter-Side Checks:

• Error Codes: Always start by checking the inverter's display for any fault codes. These are your primary diagnostic tool. For instance, a Fox ESS H1(G2)/AC1(G2) inverter might show "SW Inv Cur Fault" or "HW Inv Cur Fault" indicating high output current detected by software or hardware.
• Internal Protection: Many inverters have integrated protection mechanisms. GoodWe ET Series inverters have "AC Overcurrent Protection" and "AC Short Circuit Protection" integrated. Fox ESS H1(G2)/AC1(G2) inverters also have "AC Short-circuit Protection" and "AC Overcurrent/Overvoltage Protection" integrated. If these internal protections trigger, they might cause the inverter to shut down or disconnect, which could lead to a breaker trip.
• Settings: Incorrect inverter settings, particularly those related to output priority or grid interaction, can sometimes contribute to tripping. For example, if the inverter is trying to push too much power to the grid or battery under certain conditions, it might exceed limits. The Growatt SPF ES has various "Output source priority" settings like "Solar first" or "Utility first" that dictate how power is managed. Deye SG03LP1 offers "System Work Mode" settings such as "Selling First" or "Zero Export To Load", which control energy flow. While these don't directly trip a breaker, they influence load distribution and potential overload scenarios.

Load-Side Checks:

• Overload: This is the most frequent cause. Ensure the total power demand of your appliances does not exceed the inverter's rated output power. Remember that some appliances, especially those with motors (like refrigerators, air conditioners), have a much higher startup (inrush) current than their running current. Your inverter's surge capacity (e.g., Axpert VM III can handle 2 times its rated power for 5 seconds) is designed for these momentary peaks, but sustained or excessive inrush can still trip a breaker.
• Short Circuits: A direct short circuit in an appliance or its wiring will cause an immediate and significant current surge, tripping the breaker. Disconnect all loads and reconnect them one by one to isolate the faulty appliance.
• Ground Faults: While not always leading to a breaker trip, a ground fault (where current flows unintentionally to the ground) can trigger specific ground fault interrupter (GFI) or residual current device (RCD) breakers. Fox ESS H1(G2)/AC1(G2) inverters have a certified internal RCD to protect against electrocution, with trip thresholds of 30mA for personal protection and 300mA for fire safety. GoodWe ET Series inverters have a built-in RCMU to prevent DC residual currents up to 6mA.

Breaker Sizing and Selection: Properly sized AC and DC breakers are critical for system safety and reliable operation.

• AC Breakers: These protect the AC output circuits from the inverter to your loads and the grid connection.
• • For Axpert VM III inverters, recommended AC breakers are 16A for 1.5KW, 32A for 3KW, and 50A for 5KW models.
  • Deye SG03LP1 models recommend a 32A or 40A AC breaker for backup loads and a 40A AC breaker for the grid connection.
  • Growatt SPF ES inverters recommend a 40A AC breaker for the SPF 3500 ES and a 50A AC breaker for the SPF 5000 ES.
  • GoodWe ET Series inverters require an external AC breaker for on-grid connection, with ratings like 25A/400V for GW5K/GW5KL-ET and GW6.5K/GW6KL-ET models, and 32A/400V for GW8K/GW8KL-ET and GW10K/GW10KL-ET models.
  • Fox ESS H1(G2)/AC1(G2) inverters require a micro-breaker for max output overcurrent protection device between the inverter and grid, rated 50A for 3.0/3.7kW models and 63A for 4.6/5.0/6.0kW models.
• DC Breakers: These protect the DC circuits, primarily between the battery bank and the inverter, and sometimes between the solar panels and the inverter.
• • Axpert VM III inverters have a 150A fuse provided as over-current protection for battery supply.
  • Deye SG03LP1 models recommend DC battery breakers of 100A for the SUN-3.6K-SG, 125A for the SUN-5K-SG, and 200A for the SUN-6K-SG.
  • Growatt SPF ES inverters require a separate DC over-current protector or disconnect device between the battery and inverter. Recommended battery breakers are 100A / 60VDC for the SPF 3500 ES and 150A / 60VDC for the SPF 5000 ES.
  • Solis S5-EH1P-L inverters require a battery switch with a rated current of ≥ 80A for 3K~3.6K Models and ≥ 125A for 4.6K~6K Models. They also have an integrated DC switch and integrated AFCI (DC arc-fault circuit protection).

Always ensure that any replacement breakers match the original specifications or are appropriately sized by a professional. For detailed guidance on sizing, you can consult a /pk/tools resource or a qualified electrician.

Safety: Electrical Hazards

Working with solar systems involves high voltages and currents that can be lethal. Always prioritize safety.

• Disconnect Power: Before inspecting or working on any part of your solar system, always disconnect all power sources: the grid AC input, the solar PV input, and the battery bank. Verify zero voltage with a multimeter.
• Insulated Tools: Use only insulated tools when working on electrical connections.
• Avoid Short Circuits: A spanner or other metal object accidentally bridging terminals on a battery bank can cause a severe short circuit, leading to burns, explosions, or fire.
• Capacitor Discharge: Inverters contain capacitors that can store dangerous charges even after power is disconnected. Wait the manual's specified capacitor-discharge time before opening the unit. Opening the inverter unit should only be done by authorized service personnel.
• OCPD: Ensure Overcurrent Protection Devices (OCPDs) are correctly installed and rated for all circuits connected to the inverter, as required by local electrical codes. Solis S5-EH1P-L inverters state that OCPD is required for circuits connected to the inverter, and DC OCPD per local requirements. All PV source and output circuit conductors shall have isolators per NEC Article 690, Part II.
• Surge Protection: Fox ESS H1(G2)/AC1(G2) inverters recommend that over-voltage protection with surge arresters (SPDs) should be provided, specifically SPD type2 for DC and SPD type2 for AC, as the inverter is not fitted with SPDs in PV input or mains side.

When to call a technician instead

While basic troubleshooting can resolve many issues, some problems require professional intervention. You should call a qualified solar technician if:

• The inverter displays an error code that indicates an internal fault (e.g., "55 Over DC voltage in AC output" on an Axpert VM III or Growatt SPF ES, or "DCI Fault" on a Fox ESS H1(G2)/AC1(G2) indicating DC component is out of limit in output current).
• The breaker trips repeatedly after you have reduced the load and checked for obvious wiring issues.
• You detect burning smells, smoke, or unusual noises from the inverter or electrical components.
• You are unsure about any diagnostic step or repair, especially those involving high voltage or current.
• The issue involves grid-side faults that persist after basic checks, such as persistent "Grid transient overvoltage" (Solis S5-EH1P-L) or "Grid Volt Fault" (Fox ESS H1(G2)/AC1(G2)).
• The problem requires opening the inverter unit, as this is typically authorized-service work and may void your warranty if performed by an untrained individual. GoodWe ET Series inverters will restart themselves if overload protection is triggered, but the preparation time for restarting will increase with recurring overloads, up to one hour at most. If this cycle continues, professional help is needed.