Solar Panel (PV) Troubleshooting Guide

Use this guide when PV production is low, inconsistent, or not detected — even if no fault code is displayed.
This guide focuses on field symptoms rather than inverter fault codes.

No PV Production

What you’ll see

  • PV power = 0W
  • Inverter on, grid present
  • No PV fault code

Most common causes

  • DC isolator OFF
  • Incorrect string wiring
  • MC4 connectors not fully seated
  • PV polarity reversed
  • PV voltage outside inverter start range

Quick checks (start here)

  • Confirm DC isolator ON
  • Measure string voltage with multimeter
  • Check polarity at inverter terminals
  • Confirm PV voltage exceeds inverter start voltage

Advanced checks

  • Check roof isolator continuity

  • Inspect MC4 crimps

  • Verify PV connected to correct MPPT

See brand-specific fault codes here

Fault Codes

Low PV Production

What you’ll see

  • PV power lower than expected

  • No error codes

Most common causes

  • Shading (even partial)
  • Dirty panels
  • Incorrect tilt or orientation
  • MPPT misconfiguration
  • Grid export limit active

Quick checks (start here)

  • Inspect for shading at current time
  • Clean panels if visibly dirty
  • Confirm correct MPPT configuration
  • Check export limitation settings

One String Producing Less Than Others

What you’ll see

  • MPPT1 normal, MPPT2 low
  • String currents mismatch

Most common causes

  • Panel mismatch
  • Partial shading
  • Faulty panel
  • Loose MC4 connector

Quick checks (start here)

  • Measure string current and voltage
  • Swap strings between MPPTs
  • Inspect connectors and junction boxes

PV Voltage Too High / Too Low

What you’ll see

  • PV fault or inverter won’t start

  • Fault occurs early morning or cold days

Most common causes

  • Too many panels in series

  • Cold VOC exceeding inverter limit

  • Incorrect panel datasheet used

Quick checks (start here)

  • Calculate cold VOC

  • Compare with inverter max DC voltage

  • Confirm series panel count

PV Detected but Battery Not Charging

What you’ll see

  • PV power visible
  • Battery idle

Most common causes

  • Battery full
  • Charging disabled
  • Grid or load priority override
  • BMS charge limit active

Quick checks (start here)

  • Check battery SOC
  • Confirm charging enabled
  • Review inverter priority settings

Inverter Trips When PV Starts

What you’ll see

  • Inverter restarts when sun increases

  • PV fault or DC fault

Most common causes

  • Earth leakage

  • Insulation resistance too low

  • DC surge damage

  • Incorrect earthing

Quick checks (start here)

  • Perform insulation resistance test

  • Check DC surge arrestors

  • Inspect cable routing

PV Production Drops Intermittently

What you’ll see

  • PV fluctuates without clouds
  • Random drop-outs

Most common causes

  • Loose MC4 connectors
  • Overheating panels
  • MPPT current limit reached

Quick checks (start here)

  • Inspect all connectors
  • Check panel temperature
  • Review inverter logs

Common Installer Mistakes

  • Exceeding cold VOC limits

  • Mixing panel models in same string

  • Incorrect MC4 crimp tools

  • Running DC and AC cables together

  • Connecting unequal string lengths to same MPPT

Related Resources

Panel Datasheets

Fault Codes

Installation Guides