Solar Panel Charge Controller Troubleshooting

The solar panel’s charge controller is one of the most important safety, and functional components of the solar power system and the solar generators because of the controller controls and protects the battery from the risk of damage resulting from overcharging. It also prevents power outflow from that battery to the photovoltaic array, and this, in this way, it prevents battery drain.

Unfortunately, the charge controller doesn’t always work as is expected, and when this happens, you might end up thinking that your entire solar panel system has an issue. But since you probably don’t have the time to troubleshoot all the components of the solar panel system, it would be a good idea to have a way of detecting problems specific to the charge controller.

In this article, we look at some of the ways of troubleshooting controller problems.

But first, it’s worth noting that the solar charge controller or the regulator refers to the voltage and/ or the current regulator, which is designed to protect and enhance the longevity of the batteries and the solar system.

In this case, the controller ensures that since most of the solar panels are rated at 12V, any voltage reading above 12v,  say 20 or 24v, is controlled and brought down to protect the battery from the damaging effects of a power surge.

While you don’t need the charge controller in smaller solar systems, it is an important consideration when it comes to bigger systems.

So, how do you test to check whether the panels and the controller are working in sync or not?

Troubleshooting Solar Panel Charge Controller

To run the tests, you need to first make sure that you run a preliminary test for the solar panel system,

Test before starting

  • Check the specific voltage(V) and the current (A) for the panel. These numbers are often specified at the back of the panel.
  • Check for the sunlight conditions specified for solar panel, for the readings of the system. Note that you need to obtain the total rated output for the panel for full and bright sunlight that falls on the panel directly. Without solar power/ sun, you won’t have any power.
  • You also need to understand the function and the use of the multimeter, and you also need to know how to make the correct use of the power settings and the expected power.
  • And if you are testing the charge controller, you’d need to make sure that the battery isn’t fully charged. It won’t accept the current if the battery is charged fully.
  • Lastly, you need to make sure that when you are trying to disconnect the solar power, the battery, and the regulator, you first need to disconnect the panel from the charge regulator before disconnecting your regulator of the battery.  And when you are reconnecting these components, you’d have to connect your regulator right to the battery before connecting the solar panel. Following these steps will reduce the risk of damage to the solar charge regulator.

The other conditions you need to keep in mind include:

  • Always observe the polarities when you connect the batteries and the solar panels.
  • Be careful not to short-circuit the battery or the pane;
  • To avoid shocks, cover the front of the panel outdoors, especially for the higher-voltage solar panels, and if you are in close contact with the photovoltaic panels.

Now that we have the precautions out of the way let’s look at some of the troubleshooting steps for the charge controller.


Solar Panel Charge Controller Troubleshooting

Measuring the Open Circuit Voltage in Volts (VOC)

To measure the voltage, first, disconnect your solar panel from the regulator, and the battery then angle your solar panel to face the sun, making sure that the multimeter readings are in volts.

Next, take the voltage readings between the positive and the negative terminals. To do this, connect your negative contact on the voltmeter to the negative terminal on the panel; and the positive terminal in contact with the voltmeter and positive terminal on the solar panel. Take the readings.

Measure the Short Circuit Current, in Amps (ISC)

For this test, you need to first disconnect your solar panel from your battery and the regulator, angle your solar panel to face the sun, making sure that the multimeter readings are set at 10A for a start.

You could change the settings later. Next up, you need to take measurements of the current by connecting the positives of the lead to the voltmeter and for the panel, then the negative lead on the voltmeter to the negative terminal on the solar panel.

Measuring the Operating Current, Amps (IL)

In this test, you need to first connect the panel to the battery and the regulator, while making sure that your multimeter reading is at 10A to start with. You can change this setting later if necessary.

Now you need to connect your positive cable between the regulator and the battery and then take measurements of the operating current by connecting the +ve terminal from the multimeter to the corresponding positive cable on the regulator; then, connect the negative from meter to the battery’s positive terminal.

This measurement gives you the current from the panel plus the charge controller that is passed down to the battery. Note that connecting the meter to the wrong terminal would yield negative current readings.

If you take the readings correctly and there is an issue with the battery, for example, if the battery isn’t accepting the current fully, then the readings will be low.

Testing the controller/ regulator

You first need to take readings of the operating current as directed above, then reconnect the solar panel to the battery, minus the regulator.

Next, disconnect the positive cable that’s between the panel and the battery. Then take readings of the operating current – connect the positive end of the multimeter rod with the positive terminal on the panel, then connect the negative end of the multimeter with the battery’s positive terminal.

You would know that the controller/ regulator is faulty if you can take readings of the operating current without your regulator present and if you cannot take the same readings with the regulator/ controller connected.

You also need to keep in mind that if your battery isn’t fully charged, it may fail to accept current, hence the low readings.


These are some of the important tests that you need to run to determine whether the controller is working right or not.

But before you rule out the controller as faulty, you need to make sure that you check the fuses to make sure that they are in perfect condition. Also, verify the wiring and make sure all the wires are intact, as well as the terminals and the connections for the electrical contact. These should be working well before you rule out the controller. In case of issues with the controller, you might have to replace it.

 Bear in mind that issues with the controller, such as its inability to charge, might be a result of factors like weather, issues with the controller, the battery of the solar panel. The tests above will help you determine what the problem is.