Troubleshooting Guide: Solar Panels Not Working

You check your solar monitoring app and notice something alarming: your system’s output is zero or far below what it should be. The sun is shining brightly, but your panels aren’t generating power. Before calling your installer and paying a service visit fee, you can troubleshoot several common issues yourself. Most problems fall into a few categories: inverter faults (with specific error codes), shading from new growth, dirty panels, tripped breakers, faulty sensors, or damaged panels. This guide walks you through the most common causes and how to diagnose them systematically.

You’ll learn how to read inverter error codes, check for shading and soiling, inspect panels for visible damage, verify circuit breakers, understand why grid-tied systems shut down during outages, and when to call a professional. By the end, you’ll have narrowed down the problem and know whether it’s a DIY fix or a service call.

How to Tell Your Solar System Isn’t Working: Diagnostic Signals

Several warning signs indicate a problem:

Monitoring App Shows Zero Output: The system is designed to generate power (sunny day, time of day is appropriate), but the app displays 0 kW or 0 kWh generation.

Output Much Lower Than Expected: The app shows generation, but it’s 50%+ below what the weather and time of day suggest (e.g., 0.5 kW on a sunny noon when you should see 4–5 kW).

Utility Bill Spike: Your electricity bill is significantly higher than recent months, suggesting the solar offset isn’t happening.

No Lights on the Inverter: The inverter (usually mounted on a wall in your garage or exterior) has no lights on, isn’t humming, or isn’t displaying data on the screen.

Inverter Error Code: The display shows a fault code like “F01,” “GFDI,” or “Ground Fault” — specific error codes that help diagnosis.

If you notice any of these, start troubleshooting. Begin with the easiest checks and work toward more complex diagnostics.

Step 1: Check the Inverter and Breakers

The inverter is the first point of diagnosis:

Step 1a: Verify the Inverter is On. Look at the inverter (usually a box 2–3 feet tall in your garage or on an outdoor wall). If there’s no display or lights, the inverter may be off. Check for a physical power switch (on the side or back). Turn it on if off. Wait 5 minutes for the inverter to boot up. The display should show “Standby” or display power output numbers. If still dark, move to Step 1b.

Step 1b: Check the DC Breaker. Between the solar panels and the inverter is a DC disconnect breaker (usually near the inverter or on the roof). It’s a switch labeled “DC Disconnect” or “PV Disconnect.” It should be in the ON position (switch handle points up or to the right, depending on design). If it’s OFF, switch it ON. Wait 5 minutes for the inverter to recognize power from the panels.

Step 1c: Check the AC Breaker. Between the inverter and the electrical panel is an AC breaker. It should also be ON. If either breaker is tripped (switch is in the middle or down position), flip it OFF then back ON slowly. If it immediately trips again, there’s an electrical fault — don’t force it. Stop and call a technician.

Step 1d: Check the Main Electrical Panel. In your home‘s main breaker panel, find the circuit breaker labeled “Solar” or “Inverter” (usually a double-pole breaker). It should be ON. If OFF, flip it ON. If it won’t stay ON (keeps tripping), there’s an electrical fault — stop and call a technician.

If all breakers are ON and the inverter still shows no output after 10 minutes, proceed to Step 2.

Step 2: Read the Inverter Error Code

Modern inverters display error codes when something is wrong. Common codes and meanings:

String Inverters (SolarEdge, Fronius, Sungrow, etc.):
– F01 / Ground Fault: Electrical ground fault detected. Don’t try to fix — call a technician immediately. Ground faults can be dangerous and require professional diagnosis (bad wiring, water damage, panel degradation).
– F02 / Arc Fault: Dangerous electrical arc detected in the wiring. Stop and call immediately.
– F03 / DC Overvoltage: Panels are generating higher voltage than the inverter is rated for (rare in residential systems). Usually occurs if the array was misconfigured. Call a technician.
– F05 / AC Overvoltage: The home’s electrical voltage is too high for the inverter to inject. Usually a utility problem. Check with your utility or call a technician.
– No Error Code / Standby Only: The inverter is powered but showing “Standby,” not generating. Could be:
– Night (inverters don’t generate when there’s no sun)
– Inverter is temporarily in sleep mode (normal during cloudy weather)
– Grid is down (grid-tied systems shut down during outages for safety)
– Panels are shaded or dirty
Continue to Step 3.

Microinverters (Enphase, APsystems, etc.): Individual inverters on each panel. Check the mobile app for which microinverters are offline or faulting. Look on the offending panel for a blinking light pattern (light colors indicate status):
– Solid Red or Blinking Red: Fault condition. If one microinverter is red and others are green, the problem is on that one panel or microinverter. Check if that panel is physically damaged, its connector is loose, or if it’s shaded.
– Solid Green: Normal operation.
– Blinking Green: Communicating with network.

If most microinverters are offline, the problem is likely in the main inverter or gateway. If only one or a few are offline, the problem is isolated to those panels/microinverters.

Hybrid Inverters with Battery: Additional fault codes related to batteries:
– BATT Error / Battery Fault: Battery has a problem (internal failure, thermal issue, connection). Call a technician.
– BMS Fault: Battery Management System (BMS) isn’t communicating. Usually resolved by power-cycling the battery (turn off its breaker, wait 60 seconds, turn back on). If it persists, call a technician.

If the inverter shows no error code and displays “Standby” or similar in daylight, the problem is likely shading, soiling, or a sensor issue. Move to Step 3.

Step 3: Inspect Panels for Visible Damage and Shading

Step 3a: Visual Panel Inspection (from the ground or with binoculars). Look for:

Cracked Glass: A large visible crack across the panel. If one panel is cracked, it likely won’t generate. Have it replaced under warranty.

Delamination: The white backing material separating from the glass. The panel may still generate but is degrading. Warranty replacement is appropriate.

Dark Spots or Discoloration: Brown or black areas inside the panel usually indicate cell damage (internal shorts). This is a degradation issue; the panel likely underperforms. Check warranty claim eligibility.

Bird Nesting or Debris: Nests, branches, or accumulated leaves blocking panels. Clean away large debris yourself (if safe) or have a professional clean the roof.

Step 3b: Shading Assessment. Look for:
– New tree growth that’s now shading the panels (trees grow 12–36 inches per year; a tree that didn’t shade panels 5 years ago might now)
– Chimney, antenna, or adjacent building blocking morning or afternoon sun
– Clouds passing over (normal; not a fault)
– The sun’s angle (in winter, the sun is lower; some shading is expected and normal)

If you suspect new shading from trees, the solution is tree trimming. A 20–30% shading loss from a new tree can reduce annual output by 5–10%. Tree removal or trimming, while costly ($500–$2000), may be justified if it significantly affects system output.

Step 3c: Soiling Inspection. Look closely at the panel surfaces:
– Light Dust: Normal in dry climates. Clean if output is notably low.
– Heavy Soiling (bird droppings, pollen, dirt): Can reduce output 5–25%. Cleaning usually restores output immediately. Clean with distilled water and a soft brush or hire a professional ($200–$500 for whole roof).

If panels are visibly dirty and output is low, cleaning is the first fix to try.

Step 4: Check the Production Monitoring System

The monitoring sensor (usually a small device measuring voltage and current) might be faulty:

Step 4a: Check the Monitoring Hardware. A wireless or wired sensor is usually mounted near the inverter or on the main electrical line. If it’s disconnected (loose wire), output data won’t be recorded even if the system is generating. Check that connectors are tight and the sensor is powered (usually a small LED on the sensor indicates power).

Step 4b: Verify the App Shows Recent Updates. Open your monitoring app (Tesla app, SolarEdge dashboard, Enphase app, etc.) and check the timestamp of the last update. If it shows “Updated 2 hours ago” during daylight, data is fresh. If it shows “No update in 24 hours,” the sensor might not be communicating. Restart the app, refresh your browser, or power-cycle the monitoring gateway (a small WiFi device, usually installed indoors). Wait 5–10 minutes for reconnection.

Step 4c: Check Internet Connectivity. The monitoring system needs a WiFi or cellular connection to report data. If your WiFi is down, the monitoring app won’t show updates (but the system may still be generating — you just won’t see it). Verify your internet is working. If WiFi signal near the inverter is weak, the monitoring gateway might not connect. Move it closer to the router or install a WiFi extender.

Important Note: A faulty monitoring sensor doesn’t mean the system isn’t generating — it means you can’t see the data. The system is still working and crediting your utility bill. If output data suddenly disappears but your utility bill is normal, it’s likely a monitoring issue, not a generation issue.

Step 5: Verify the Grid is Not Down (Grid-Tied Systems Only)

Grid-tied solar systems are required to shut down during a grid outage for safety (to prevent backfeeding dangerous voltage into utility lines being worked on). If the grid is down, your system won’t generate (you’ll also have no power in the house).

Step 5a: Check if the Utility Grid is Down. Look for:
– Power outages reported on your utility’s website or app
– Street lights off (often powered by the utility grid)
– Neighbors’ lights off
– A message in your inverter display like “Grid Fault” or “Anti-Islanding Activated”

If there’s a widespread outage, there’s nothing you can do — the system will resume generating when the grid is restored (usually within minutes to hours). Your home will have power again only when the grid is restored (unless you have battery backup).

Step 5b: Test with a Battery System (If You Have One). If your system includes battery storage (Tesla Powerwall, LG Chem, Enphase IQ Battery), the system should generate and charge the battery even if the grid is down. If the grid is down and the battery isn’t charging, there’s a problem with the battery or solar charging circuit — call a technician.

Step 5c: If the Grid is Up and System Still Shows No Output. Proceed to Step 6 or contact a technician. If the grid is up and the inverter is in “Standby,” it may be waiting for grid voltage to stabilize (normal after an outage). Give it 5–10 minutes.

Step 6: Check for Loose Connections and Corrosion

Loose or corroded connections can block power flow:

DC Side (Panels to Inverter):
– Locate the DC combiner box or string combiner (a junction box where panel wiring comes together). It’s usually near the inverter.
– Check that all connectors are fully seated (pushed together, not loose).
– Look for green corrosion on copper connectors (indicates moisture damage). Loose or corroded connectors reduce output or cause the system to fault.
– Don’t open the combiner box yourself; if you suspect corrosion, call a technician. High-voltage DC is dangerous.

AC Side (Inverter to Panel and Breaker):
– Check the AC wiring connection from the inverter to the breaker. Look for loose wire nuts or corroded connections.
– Loose AC connections typically cause breaker trips or arcing, not silent shutdowns, but worth checking.

Most homeowners can visually inspect for loose or corroded connectors, but don’t disassemble anything. If you suspect corrosion, a technician must investigate.

Step 7: Check for Optimizer or Microinverter Faults (If You Have Them)

If You Have Power Optimizers (SolarEdge):
– Each panel has a small power optimizer that conditions the power before sending it to the string inverter.
– In the SolarEdge app, navigate to “Devices” and look for optimizers that show “Offline” or “Faulty.”
– If one or more optimizers are offline, the corresponding panel(s) aren’t sending power. Possible causes:
– Optimizer has lost power (check its DC connector)
– Optimizer has internally faulted (rare but possible after lightning strike or power surge)
– Panel is disconnected

– If one optimizer is faulty, production is reduced but not eliminated (other panels still work). Call a technician to diagnose or replace the faulty optimizer.

If You Have Microinverters (Enphase, APsystems):
– Each panel has its own small inverter. An offline microinverter means that panel isn’t generating.
– Check the Enphase or APsystems app for offline microinverters. They usually display a specific error code or “offline” status.
– To diagnose an offline microinverter:
1. Walk to the panel and look at the inverter’s status light (color or blinking pattern).
2. Check if the inverter’s AC wire is connected to the combiner.
3. Check if the inverter’s DC connectors to the panel are tight.
4. If everything looks connected, the microinverter may have failed internally. Replacement under warranty is typical.

– If one microinverter is down, that panel’s output is lost, but others continue. A single offline microinverter typically reduces system output by 5–10%.

Step 8: Seasonal and Time-of-Day Expectations

Before you assume there’s a fault, verify your expectations are realistic:

Winter vs. Summer Output: A system generating 3 kW on a clear summer day might only generate 1.5 kW on a clear winter day (lower sun angle). This is normal, not a fault.

Cloudy Days: On overcast days, output drops 50–80% even if the inverter is working fine. An inverter in “Standby” on a cloudy day is normal — once clouds clear, output should resume.

Early Morning and Late Afternoon: The sun’s angle is low, so output is low. At 7 AM or 5 PM, output might be 500 W even on a clear day. As the sun rises higher, output increases. This is normal.

Night: Inverters don’t generate at night — this is expected. Inverters usually display “Sleep Mode” or “Night Mode” after sunset.

Compare your output to your monitoring app’s historical data. If today’s output is similar to the same day last year (accounting for weather), the system is working normally.

When to Call a Technician

Call a professional if:

– Inverter shows a fault code (F01, F02, F03, F05, GFDI, Ground Fault, Arc Fault, or similar)
– Multiple breakers keep tripping
– You discover a cracked or delaminated panel
– Output is mysteriously low on a clear day and visual inspection shows no shading or dirt
– A microinverter or optimizer is offline and won’t come back online after restarting
– You suspect water damage (moisture inside combiner box, corrosion on connectors, wet wiring)
– The system has been generating normally but suddenly drops to zero with no visible cause

A service call typically costs $150–$300 for diagnosis plus parts and labor for repairs. Many installers offer 5–10 year warranties on workmanship, so repairs within the warranty period may be free.

Frequently Asked Questions

Summing Up

When your solar system stops working or underperforms, the cause is usually one of a few common issues: inverter fault or tripped breaker, new shading, dirty panels, faulty monitoring sensor, or grid outage. By working systematically through the diagnostic steps in this guide — checking breakers, reading error codes, inspecting for shading and soiling, and verifying grid status — you can narrow down the problem and determine whether it’s a DIY fix (cleaning panels, resetting breakers) or a service call. For electrical faults (ground faults, arc faults, persistent breaker trips) or hardware failures (cracked panels, offline microinverters), professional diagnosis is essential. Most failures are under warranty if they occur within 5–10 years of installation. The 30% federal Investment Tax Credit remains active through 2032, and solar systems are designed to operate reliably for 25+ years — most downtime is temporary and easily resolved.

If you’ve gone through the diagnostic steps and still can’t identify the problem, or if you’re seeing fault codes and need professional help, contact our solar service team. Call (855) 427-0058 for rapid troubleshooting and service scheduling. We can often diagnose issues over the phone and send a technician if needed. Visit us.solarpanelsnetwork.com for service options and warranty information.

Updated May 2026