Solar Combiner Box Troubleshooting

Home Solar Combiner Box Troubleshooting

Solar panels convert solar energy to electricity. They are the new way of living and have been employed and praised worldwide for revolutionizing green energy. However, like any invention, solar panels are also not short of drawbacks.

Solar panels consist of a set of elements and functions which are perfectly and safely equipped in a combiner box. These combiner boxes encase the components safely; however, they face some troubles too.

So here is a guide on solar combiner box failures and the troubleshooting steps.

Why Does a Solar Combiner Box Stop Working?

Solar panel with combiner box on rooftop
Source: Unsplash

Though rare, solar panels are not invincible. Sometimes, minor errors can arise and cause the solar panel to stop functioning properly. 

Although it might be challenging to identify the precise cause of faults, if you are wondering why solar panels not working, here is the list of some common issues that prevent solar panels from operating without interruption are those listed below.

Faulty Solar Meter

One of the main causes of PV system failures is faulty solar meters. The panels genuinely function well; however, the meter cannot accurately read solar energy generation.

One cause of this is the gradual obsolescence of solar meters. Although they use the most recent cellular technology, telecom companies frequently stop supporting them as newer protocols appear. 

Additionally, some solar meters rely on your home’s Internet connection, which is prone to disconnect due to signal loss or provider changes. Other times, all that has to be fixed is faulty software or hardware.

Breaker Switches

Your home’s fuses that regulate electrical flow can occasionally malfunction. If you open up your breaker box and check to see if any switches are in the “off” position, you may easily identify if this is the issue.

Dirt & Dust

The function of the solar panels might also be hampered by dirt and dust accumulated inside them. As the dirt and debris build up, they obstruct the sun’s rays, reducing the amount of solar electricity generated.

Other causes include shoddy installation work, outdated or overloaded wiring, weather-beaten components, failed micro-inverters, rodent-caused component damage, and broken panels.

Steps to Identify Common Solar Combiner Faults

Inside of a solar combiner box
Source: Beny

Amperage measurements and computations are essential for determining whether the PV arrays function properly when troubleshooting combiner boxes. You can tell whether a cell has malfunctioned by measuring current on individual arrays or combining current readings.

  • Verify the tightness of all wire connections. A loose connection could result in the inverter’s voltage output or current fluctuating.
  • Check each fuse in the box. Verify that the resistance and continuity are correct.
  • Validate the aggregate output current and voltage to the inverter by measuring and calculating the input current and voltage from the arrays. You can tell whether a cell has malfunctioned by measuring current on individual arrays or combining current readings.

The key to effectively troubleshooting PV systems is to be thorough and to use rated instruments for the task. It’s also about safety as solar systems and loads grow more sophisticated.

A CAT III 1,500-V rated AC/DC clamp meter with DC power, audio polarity, visual continuity, and a thinner jaw design for tight spaces is currently the best all-around tool. These features are specifically designed for testing and measurement in solar PV applications.

Most Common Solar Combiner Issues and How to Fix

Man installing solar panels
Source: Unsplash

The best course of action regarding PV combiner box problems is to let a pro handle the troubleshooting. Some typical solar combiner problems can be quickly resolved using the troubleshooting mentioned above techniques, while not every problem needs a specialist’s assistance.

Communication Failure 

Follow the troubleshooting methods below if an unforeseen communication failure occurs:

  • Verify that the host computer monitoring software’s address matches the address of the combiner box that must be verified.
  • Verify that the baud rate of the solar string box to be checked is consistent with the communication baud rate established by the host computer monitoring program.
  • Communication line interference: Verify that 120 termination resistance is connected to the appropriate communication bus terminal.

Failure of the Lightning Protection Mechanism

Lighting is one of the main causes of failures in solar combiner boxes because of the jarring electric surge it causes.

Check to see if the lightning protector’s status feedback wiring is solid. If the contact is functional, the surge protector has malfunctioned and must be replaced immediately.

Current Sampling Problem

Please examine the fuse and PV array to see if the current sampling display value of one channel is much larger or smaller than other channels.

Solar Combiner Box Daily Maintenance Guide

Solar panels in open ground
Source: Unsplash

One must follow a regular maintenance schedule to extend the durability and efficiency of the solar combiner box after spending money on the device’s purchase or diagnosing its issue.

Routine Maintenance

Failure in combiner boxes is not usually due to electrical disturbances. It may occasionally only be a minor problem brought on by unanticipated factors like dust, humidity, or changing temperatures.

To ensure that the solar combiner will function well and have a long service life, one must first confirm that the necessary maintainers will be required.

Remember that stopping the solar box will be necessary whenever maintainers are required to ensure that the contacting party is not charged. Remove the fuse after making sure all currents are zero.

Another thing to remember is that the high voltage from the board and inverter can damage the fuse. You must therefore avoid touching the fuse while it is operating.

Ensure the Direct Current circuit breaker is disconnected before installing and testing the fuse. Don’t forget that the direct current circuit breaker still has high voltages at both ends.

Last but not least, protect yourself by putting on insulated gloves when performing maintenance.

Fuse Replacement

The fuse cannot be repaired once it has burnt. Therefore, the first step in replacing a fuse is to turn the circuit breaker on.

Remember not to open and close the fuse box while it is under load. That could result in the fuse being harmed.

Troubleshooting Safety 

Before working on the combiner box, ensure the Direct Current circuit breaker is disconnected. This separates the combiner box from the direct current output of the combiner.

Remember that there is still a high voltage at the fuse holder’s two ends while you remove all the fuses.


Solar combiner boxes may not be invincible, but they are easy to fix if any error occurs. We hope you were able to understand the solar combiner box troubleshooting. To avoid repetitive errors from occurring, it is best to invest in affordable and superior quality solar combiner boxes.

If you are happening to look for solar combiner boxes for your OEM or wholesale businesses, check out Beny

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