Something doesn’t look right with your solar system? Use this guide to diagnose common problems — and know when to call in a professional.
Tap each problem to see what to check and what it means.
Check for shading: New tree growth, a neighbour’s extension, or even a satellite dish can cast shadows that dramatically reduce output. Walk around your property mid-morning and mid-afternoon to spot new shading sources.
Panel cleanliness: Bird droppings, dust, and organic build-up reduce panel efficiency by 10–20%. If you haven’t cleaned panels in over 6 months, this is the most likely cause.
Inverter error log: Log into your inverter’s monitoring portal or app and check for any logged warnings in the past 30 days. Even intermittent faults reduce daily output totals.
Seasonal factor: Cloudy months and the northeast monsoon season naturally reduce generation. Compare month-on-month from the same month last year, not the previous month.
Isolation Fault (Insulation Fault): The inverter has detected a drop in insulation resistance in the DC wiring. This is a safety alert — do NOT reset without investigation. Switch off the DC isolator and contact your installer. This fault typically requires a licensed electrician.
Grid Fault / AC Fault: The grid voltage or frequency went outside acceptable limits. This often resolves on its own once the grid stabilises. Wait 5–10 minutes; the inverter will reconnect automatically. If it persists for hours, call your utility provider (TNB helpline: 1-800-88-5454).
Overcurrent / Overload: More current is flowing than the inverter is rated for. This can indicate a panel string fault or wiring issue. Switch off and call your installer — do not attempt to reset multiple times.
Temperature fault: The inverter has overheated. Check that its ventilation clearance has not been blocked (e.g. by a storage box placed in front). Ensure it is not in direct afternoon sun. Most thermal faults clear after 30–60 minutes of cooling.
Check for a grid outage: Grid-tied solar systems are required by law to shut down during power outages (anti-islanding protection). Check whether your neighbours also have no power. If yes, your system is working correctly — it will restart automatically when the grid returns.
DC isolator switch: Located near the inverter (usually a red or black rotary switch labelled "DC ISOLATOR" or "SOLAR ISOLATOR"). Ensure it is in the ON position. If it has tripped, reset it once. If it trips again immediately, call your installer.
AC circuit breaker: In your distribution board, check the MCB labelled "SOLAR" or "PV SYSTEM". If it has tripped, reset once. Repeated tripping indicates a fault that needs professional attention.
Inverter power light: Is the inverter displaying anything at all? A completely dark inverter (no lights, no display) may indicate an AC supply issue to the inverter itself. Check the dedicated MCB in your DB.
WiFi connection: The monitoring dongle (a small device plugged into your inverter) connects to your home WiFi. If you recently changed your WiFi password or router, the dongle will have lost its connection. You will need to reconfigure it using the inverter manufacturer’s app.
Monitoring dongle LEDs: Check the dongle’s indicator lights. Solid green = connected. Flashing green = connecting. Red or amber = fault. Unplug and replug the dongle, then wait 2 minutes for it to reconnect.
Cloud server outage: Sometimes the manufacturer’s cloud platform experiences downtime. Check the manufacturer’s social media or status page. Your system is likely still generating — you simply cannot see the data until the cloud recovers.
4G/SIM-based monitoring: If your system uses a mobile data dongle instead of WiFi, check that the SIM has active data and that there is mobile coverage at your location.
Normal sounds: A steady, low-frequency hum (the transformer) and the sound of a cooling fan spinning up on hot days or during peak generation hours are completely normal. A soft "click" at sunrise and sunset when the inverter connects and disconnects from the grid is also normal.
Concern — loud buzzing: A harsh buzzing or vibrating sound often indicates a failing cooling fan. Left unchecked, an overheating inverter will trigger thermal shutdowns and reduce its lifespan. Schedule a service call.
Concern — rattling or knocking: Loose internal components or mounting bracket vibration. Switch off the inverter and contact your installer — loose components can cause shorts.
Concern — crackling or popping: This is not normal and suggests electrical arcing. Switch off the DC isolator and AC breaker immediately and call your installer.
Why it matters: Birds nesting under panels leave droppings that shade cells and corrode aluminium frames. Pigeons and mynas also peck at DC cables, which can cause insulation faults and in rare cases fire risks.
Bird mesh (spikes/exclusion): A galvanised steel mesh or clip-on bird guard system installed around the perimeter of your panel array is the most effective long-term solution. This should be installed by a professional who can work safely at roof level.
Cable protection: Ask your O&M provider to inspect DC cable conduit integrity during your next service. Cables running along rafters or across the roof surface are most at risk.
Immediate action: Do not attempt to remove active nests yourself during nesting season. Contact a pest control specialist first, then engage your solar installer to assess any cable damage.
Know your limits — some checks are safe for homeowners; others require a licensed technician.
| You can check yourself | Requires a licensed technician |
|---|---|
| Check inverter display and status lights | Any work on DC wiring or combiner boxes |
| Reset a tripped MCB (once only) | Thermal imaging / IV curve testing |
| Reconnect monitoring dongle WiFi | Earthing continuity and insulation resistance testing |
| Visual inspection for obvious shading | Bird mesh installation at roof level |
| Ground-level panel cleaning | Connector re-crimping or cable replacement |
| Check DC and AC isolator switch positions | Any repair after an error code keeps returning |
Most inverters use a simple traffic-light system. Here’s what each colour means.
Solid green means full output. Flashing green means low-light or morning ramp-up.
Often self-resolves. Monitor for 30 minutes. If orange persists all day, call your installer.
Photograph the error code. Switch off DC isolator. Call your installer or Trexon support.
More answers to common solar troubleshooting questions.
Not necessarily. First check: (1) Is there a power outage in your area? Grid-tied systems shut off automatically during outages for safety. (2) Is it overcast or raining heavily? Output can drop significantly. (3) Is your monitoring dongle's WiFi connected? Check the dongle LED — a flashing or red light means it's offline. If all looks fine and it's a sunny day, call your installer.
Most inverters display codes like E001, F01, or similar. Common codes: "Isolation Fault" means a wiring insulation issue — call a technician. "Grid Fault" often resolves when the grid stabilises — wait 5 minutes. "Overcurrent" suggests a potential short — switch off the DC isolator and call your installer. Always photograph the error code before resetting.
Seasonal variation is normal. Malaysia's monsoon months (October–January for Peninsula east coast, November–February for west coast) reduce generation by 10–30%. Also check: Has anything new shaded your panels (new tree growth, neighbour's structure)? Has it been more than 12 months since your last panel clean? Dust and bird droppings reduce output by up to 20%.
A low-frequency hum is completely normal — it's the inverter's cooling fan running during peak generation hours. You may also hear a faint click when the system switches on and off at sunrise and sunset. Concern: loud buzzing, rattling, or irregular clicking sounds indicate a fault. Switch off and contact your installer if you hear these.
Basic cleaning is safe if you can reach the panels from ground level or a stable ladder. Use a soft brush or microfibre cloth with plain water or a mild soap solution. Never use abrasive materials or high-pressure washers — this can scratch the glass or force water under the panel frame. For roof-level work, hire a professional with proper safety equipment.
We recommend an annual O&M inspection covering electrical connections, cable condition, earthing, inverter performance, and panel cleanliness. If your system is over 5 years old or you've had any error codes, consider adding a thermal imaging scan to detect hotspots before they become serious faults.
Our trained technicians can diagnose and resolve most faults within 48 hours. Book a service call or schedule your annual O&M inspection.
Professional operations & maintenance packages — from basic cleaning to full thermal imaging
Deionized water cleaning service that restores full panel output
Understanding solar fire risks and the safety features that protect your home
Understand the full system — panels, inverter, net metering — before diagnosing issues