🔧 Troubleshooting Guide

SunFusion Energy Systems | Interactive Diagnostic Flowcharts

⚡

Electrical Troubleshooting

General electrical system diagnostics and fault isolation

🔴 NO POWER / COMPLETE OUTAGE ▶ Click to expand
INITIAL ASSESSMENT:
✓ Complete loss of power to entire structure
✓ No lights, no outlets, no appliances working
✓ Follow the diagnostic steps below
↓ Check First
🔍 Main Breaker Tripped? ▶ Click for solutions
SOLUTIONS:
✓ Reset main breaker (OFF → ON)
✓ If trips immediately: short circuit present
✓ If trips under load: overload condition
✓ Check for burning smell or visible damage
↓ If OK
🏠 Utility Power Present? ▶ Click for solutions
SOLUTIONS:
✓ Check utility meter for display/power
✓ Verify neighbors have power
✓ Contact utility company if outage confirmed
✓ Check for downed lines (DO NOT TOUCH)
↓ If OK
🔧 Service Entrance Connections ▶ Click for solutions
SOLUTIONS:
✓ Verify tight connections at meter base
✓ Check weatherhead connections
✓ Inspect for corrosion or heat damage
✓ Test voltage at main lugs (should be 240V)
🟡 PARTIAL POWER / SOME CIRCUITS DEAD ▶ Click to expand
SYMPTOMS:
✓ Some rooms/circuits have power, others don't
✓ Half of outlets not working
✓ 240V appliances not working (dryer, range, A/C)
↓ Check First
🔍 Individual Breakers Tripped? ▶ Click for solutions
SOLUTIONS:
✓ Identify and reset tripped breakers
✓ Note which circuits are affected
✓ Check for loose breaker connections
✓ Verify breaker is fully seated in panel
↓ If OK
⚠️ Lost One Leg of Power? ▶ Click for solutions
SOLUTIONS:
✓ Test both legs at main panel (120V each to neutral)
✓ Only 120V total = lost leg condition
✓ Check utility connections immediately
✓ This is a utility emergency - report to power company
↓ If OK
🔌 GFCI/AFCI Tripped Upstream? ▶ Click for solutions
SOLUTIONS:
✓ Locate and test all GFCI outlets
✓ Check AFCI breakers in panel
✓ Reset protection devices
✓ If trips repeatedly: ground fault or arc fault present
💡 VOLTAGE PROBLEMS / FLICKERING ▶ Click to expand
SYMPTOMS:
✓ Lights flickering or dimming
✓ Appliances running slow or fast
✓ Electronics shutting down unexpectedly
↓ Check First
📊 Measure Voltage at Panel ▶ Click for solutions
SOLUTIONS:
✓ L1 to Neutral: Should be 120V ±5%
✓ L2 to Neutral: Should be 120V ±5%
✓ L1 to L2: Should be 240V ±5%
✓ If unbalanced: utility or connection issue
↓ If Low
🔧 Check Neutral Connection ▶ Click for solutions
SOLUTIONS:
✓ Loose neutral = voltage fluctuation
✓ Check neutral bar connections in panel
✓ Verify neutral at meter base
✓ DANGER: Floating neutral can cause 240V on 120V circuits
↓ If OK
📞 Contact Utility for Transformer Check ▶ Click for solutions
SOLUTIONS:
✓ Request voltage check at transformer
✓ May be tap setting issue
✓ Neighborhood-wide = utility problem
✓ Document voltage readings with timestamps
🔴 GROUND FAULT / GFCI KEEPS TRIPPING ▶ Click to expand
SYMPTOMS:
✓ GFCI outlet won't reset
✓ Trips immediately after reset
✓ Multiple outlets on same circuit affected
↓ Isolate
🔌 Disconnect All Loads ▶ Click for solutions
SOLUTIONS:
✓ Unplug everything on circuit
✓ Reset GFCI
✓ If holds: problem is in a device
✓ Reconnect one at a time to identify fault
↓ Still Trips
🔍 Check Wiring for Damage ▶ Click for solutions
SOLUTIONS:
✓ Inspect wire insulation for nicks/cuts
✓ Check junction boxes for moisture
✓ Look for rodent damage
✓ Verify proper wire terminations
↓ If OK
⚠️ GFCI Device May Be Faulty ▶ Click for solutions
SOLUTIONS:
✓ GFCI outlets can fail (especially in harsh environments)
✓ Replace GFCI with new device
✓ Test with GFCI tester after replacement
✓ If new GFCI trips: wiring fault exists
☀️

Solar PV Troubleshooting

Photovoltaic system diagnostics and performance issues

🔴 ZERO SOLAR PRODUCTION ▶ Click to expand
SYMPTOMS:
✓ Inverter shows 0 watts output
✓ No energy production on monitoring
✓ System appears completely offline
↓ Check First
📟 Inverter Status/Display ▶ Click for solutions
SOLUTIONS:
✓ Check for error codes on display
✓ Verify AC and DC disconnect switches are ON
✓ Look for fault LEDs or warning indicators
✓ Note any error codes for troubleshooting
↓ No Display
⚡ AC Power to Inverter? ▶ Click for solutions
SOLUTIONS:
✓ Check AC breaker at main panel
✓ Verify AC disconnect is ON
✓ Test voltage at inverter AC input
✓ Check for tripped breaker or blown fuse
↓ If OK
🔋 DC Voltage from Array? ▶ Click for solutions
SOLUTIONS:
✓ Measure Voc at inverter DC input
✓ Should be within inverter's MPPT range
✓ Zero volts = string issue or DC disconnect OFF
✓ Low voltage = shading, damage, or connection issue
🟡 LOW SOLAR PRODUCTION ▶ Click to expand
SYMPTOMS:
✓ Production below expected levels
✓ One string underperforming others
✓ Gradual decline in output over time
↓ Check First
🌤️ Shading or Soiling? ▶ Click for solutions
SOLUTIONS:
✓ Inspect panels for debris, bird droppings, pollen
✓ Check for new shading (tree growth, structures)
✓ Look for partial shading patterns
✓ Clean panels if soiled (use appropriate methods)
↓ If Clean
📊 Compare String Voltages ▶ Click for solutions
SOLUTIONS:
✓ Measure Voc of each string individually
✓ Strings should be within 5% of each other
✓ Low string = panel issue or connection
✓ Calculate expected Voc: (# panels × Voc rating)
↓ If Unequal
🔍 Inspect Connections & Panels ▶ Click for solutions
SOLUTIONS:
✓ Check MC4 connectors for security and corrosion
✓ Look for burnt or melted connectors
✓ Inspect panel junction boxes if accessible
✓ Check for cracked or damaged panels
✓ Use thermal camera to identify hot spots
⚠️ INVERTER FAULT / ERROR CODE ▶ Click to expand
COMMON ERROR TYPES:
✓ Ground Fault, Arc Fault, Grid Fault, Over-Temperature
✓ Click each error type below for specific solutions
↓ Common Codes
🔌 Ground Fault Error ▶ Click for solutions
SOLUTIONS:
✓ Indicates DC ground fault in array
✓ Check all MC4 connections for moisture
✓ Inspect conduit for water intrusion
✓ Use megger to test insulation resistance
✓ Isolate strings to identify fault location
↓
⚡ Arc Fault Error ▶ Click for solutions
SOLUTIONS:
✓ Series arc detected in DC wiring
✓ Inspect all connections for looseness
✓ Check for damaged wire insulation
✓ Look for burnt or melted components
✓ May require string-by-string isolation
↓
🏠 Grid Fault / AC Error ▶ Click for solutions
SOLUTIONS:
✓ Grid voltage or frequency out of spec
✓ Check utility voltage at service entrance
✓ May be utility issue - wait and retry
✓ If persistent: contact utility
✓ Check AC wiring connections to inverter
↓
🌡️ Over-Temperature Error ▶ Click for solutions
SOLUTIONS:
✓ Inverter thermal protection activated
✓ Check ventilation and clearances
✓ Clean any dust from vents/heatsinks
✓ Verify ambient temp is within spec
✓ May need to relocate or add shade structure
🔧 STRING ISOLATION PROCEDURE ▶ Click to expand
WHEN TO USE:
✓ Locating ground faults or arc faults
✓ Identifying underperforming strings
✓ Panel-level diagnostics
↓ Step 1
⚠️ Safety First ▶ Click for solutions
SAFETY STEPS:
✓ Turn OFF AC disconnect
✓ Turn OFF DC disconnect
✓ Wait 5 minutes for capacitors to discharge
✓ Use appropriate PPE (gloves, safety glasses)
✓ Be aware: panels produce voltage when illuminated
↓ Step 2
🔌 Isolate Individual Strings ▶ Click for solutions
PROCEDURE:
✓ Disconnect all strings at combiner or inverter
✓ Test each string Voc individually
✓ Compare to expected value
✓ Identify underperforming string
↓ Step 3
✅ Panel-Level Testing ▶ Click for solutions
FINAL STEPS:
✓ For problem string: test panel by panel
✓ Measure Voc at each panel junction box
✓ Look for panel significantly lower than others
✓ Check for bypass diode activation (hot spots)
🔋

ESS Troubleshooting

Energy Storage System / Battery diagnostics for Sol-Ark & Guardian systems

🔴 BATTERY NOT CHARGING ▶ Click to expand
SYMPTOMS:
✓ SOC not increasing despite power available
✓ Inverter shows 0A to battery
✓ Battery remains at low SOC
↓ Check First
⚡ Verify Power Source Available ▶ Click for solutions
SOLUTIONS:
✓ Solar: Check PV production on inverter display
✓ Grid: Verify AC input voltage present
✓ Generator: Confirm generator is running and connected
✓ Check that charging source is enabled in settings
↓ If OK
📡 Battery BMS Communication ▶ Click for solutions
SOLUTIONS:
✓ Check CAN/RS485 communication cable connections
✓ Verify BMS LED indicators on battery
✓ Look for communication errors on inverter
✓ Check BMS firmware version compatibility
↓ If OK
📊 Battery State of Charge ▶ Click for solutions
SOLUTIONS:
✓ If SOC shows 100%: battery is full, no charging needed
✓ If SOC is inaccurate: may need calibration cycle
✓ Check charge voltage limits in settings
✓ Verify battery is not in protection mode
🟡 BATTERY NOT DISCHARGING / NO BACKUP ▶ Click to expand
SYMPTOMS:
✓ Battery has charge but won't power loads
✓ Grid outage but no backup power
✓ Self-consumption mode not working
↓ Check First
⚙️ Operating Mode Settings ▶ Click for solutions
SOLUTIONS:
✓ Verify system is in correct mode (Self-Use, Backup, etc.)
✓ Check discharge time windows if programmed
✓ Confirm backup/critical loads panel is wired correctly
✓ Review grid-tie vs off-grid configuration
↓ If OK
📉 Battery SOC Limits ▶ Click for solutions
SOLUTIONS:
✓ Check minimum SOC reserve setting
✓ If current SOC ≤ reserve: battery won't discharge
✓ Grid mode reserve is often 10-20%
✓ Backup mode reserve may be different
↓ If OK
⚡ Discharge Current Limits ▶ Click for solutions
SOLUTIONS:
✓ Check max discharge rate setting
✓ Verify load doesn't exceed battery capacity
✓ Check for BMS discharge protection active
✓ Temperature limits may reduce discharge rate
⚠️ BMS FAULT / BATTERY ALARM ▶ Click to expand
COMMON FAULT TYPES:
✓ Cell voltage, temperature, overcurrent, communication
✓ Click each fault type below for specific solutions
↓ Common Faults
📊 Cell Overvoltage / Undervoltage ▶ Click for solutions
SOLUTIONS:
✓ Overvoltage (>3.65V/cell LFP): Stop charging immediately
✓ Undervoltage (<2.5V/cell LFP): Stop discharging, charge gently
✓ Check for cell imbalance in BMS data
✓ May require top-balance procedure
✓ Persistent issues: possible cell failure
↓
🌡️ Over-Temperature Alarm ▶ Click for solutions
SOLUTIONS:
✓ Check battery ambient temperature
✓ LiFePO4 charge range: 0°C to 45°C (32°F to 113°F)
✓ LiFePO4 discharge range: -20°C to 60°C (-4°F to 140°F)
✓ Verify adequate ventilation around batteries
✓ Check for direct sunlight exposure
↓
⚡ Overcurrent Protection ▶ Click for solutions
SOLUTIONS:
✓ Load exceeded battery max discharge rate
✓ Check total load on critical/backup panel
✓ May need to reduce connected loads
✓ Verify wire sizing for battery current
✓ Check for short circuit in load wiring
↓
📡 Communication Fault ▶ Click for solutions
SOLUTIONS:
✓ Check CAN bus cable connections (tight, no corrosion)
✓ Verify correct cable pinout for your system
✓ Check termination resistors if required
✓ Try rebooting BMS (power cycle battery)
✓ Update firmware if available
🔄 BACKUP TRANSITION ISSUES ▶ Click to expand
SYMPTOMS:
✓ Loads don't transfer during outage
✓ Momentary loss then no backup
✓ Delayed or failed transition
↓ Check First
🔌 Transfer Switch Operation ▶ Click for solutions
SOLUTIONS:
✓ Sol-Ark: Built-in transfer, check relay clicking
✓ External ATS: Verify ATS is functioning
✓ Test manual transfer if available
✓ Check transfer time setting (if adjustable)
↓ If OK
🔧 Critical Loads Panel Wiring ▶ Click for solutions
SOLUTIONS:
✓ Verify backup loads are on correct panel
✓ Check neutral bonding configuration
✓ Confirm ground-neutral bond location
✓ Test with intentional grid disconnect
↓ If OK
⚙️ Inverter Backup Settings ▶ Click for solutions
SOLUTIONS:
✓ Verify backup function is enabled
✓ Check grid-loss detection sensitivity
✓ Confirm battery SOC above backup reserve
✓ Review UPS vs Backup mode settings
📊 INACCURATE STATE OF CHARGE (SOC) ▶ Click to expand
SYMPTOMS:
✓ SOC suddenly jumps up or down
✓ Shows 0% but battery still has power
✓ Shows 100% but charges more
✓ Runtime doesn't match SOC
↓ Solution
🔄 SOC Calibration Cycle ▶ Click for solutions
CALIBRATION PROCEDURE:
1. Fully charge battery to 100% (absorption complete)
2. Let rest for 1 hour at 100%
3. Discharge to minimum SOC (10-20%)
4. Immediately recharge to 100%
5. BMS should recalibrate SOC
✓ Repeat if necessary
↓ If Still Wrong
⚠️ Check Cell Balance ▶ Click for solutions
SOLUTIONS:
✓ Access BMS cell voltage data
✓ All cells should be within 0.05V of each other
✓ Large imbalance = weak cell or connection
✓ May require manual top-balance procedure
✓ Contact manufacturer if cells won't balance

💡 Click on any node to expand troubleshooting solutions

© SunFusion Energy Systems Inc. | License #1053778 | San Diego, CA

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