10 Reasons Why a Solar Panel Inverter Isn’t Working

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The demand for electrical energy is increasing day by day, and the energy market is moving towards a distributed energy system in which local generation will serve the local load. A solar energy system is one of the solutions available to meet energy demands, but the output of solar panels is DC and nearly all of our loads run on AC. To convert DC into AC, we need a device called inverter. If this device is not working properly or not giving proper output, the reliability of an electrical system becomes questionable. In this article, we discuss tens reasons for why an inverter would not be working or not providing enough output to meet the load demand.

There are ten reasons why a solar inverter would not be giving any output or why your local load is not running while connected to your solar inverter. One reason can be the tripping of protection devices that are connected within the system to protect some or all of the components. This protection can be triggered due to overcurrent, being over voltage or under voltage, or due to the frequency of the electrical system. A solar inverter can only give output within a specific range of solar voltages. If, due to poor system design, the voltage is higher than the maximum limit or lower than the minimum limit, the inverter will shut down.

An inverter will also shut down if the connected load is too high. Another of the reasons for solar inverters not working is overheating. This overheating can cause by either a blocked fan, a blocked air filter, or a rise in environmental temperature.

Each manufacturer provides a user manual for each type of inverter that contains the error signals that an inverter will give when it isn’t functioning properly. There is a wide range of error signals either displayed on-screen or indicated by LED lights. By looking at the information in your corresponding manual, you can clearly identify the problem and find the solution there as well. However, make sure your own safety is taken into account when trying to resolve such issues; if you don’t feel comfortable working with electrical power, call a professional or contact the manufacturer for further guidance.

Protection is tripped

Each electrical system is equipped with protection devices to prevent catastrophe, even in the case of a short circuit or other malfunction of your equipment. If you are not getting output from your inverter, the first thing you need to check is the protection devices.

#1: Overcurrent or Short Circuit

If the system has circuit breakers at the output point of the inverter (between the inverter and the load), you will need to check this first. If for any reason the circuit breaker is tripped, the output will be cut off and the load will not run. It is typical that an inverter comes equipped with such protections to protect the main inverter components.

So, if inverter is giving output but load is not working, you have to clear the fault and again turn on the circuit breaker. If circuit breaker is not present or not tripped, then you have to look for inverter’s error on screen or indication to check if internal circuit breaker or fuse of inverter is blown.

#2: Over Voltage or Under Voltage Protection

There is also overvoltage protection in most modern solar inverters. If the solar inverter is connected with a grid and the grid voltage goes high or low, the inverter can either go into solar mode or, if solar energy is not present, you will simply just see no output at the solar inverter.

This error will go away when the voltages are stabilized.

Voltage is Not Sufficient

Each solar inverter has its own specific range of voltages between which it can work. The starting voltage of an inverter is also typically mentioned in the accompanying datasheet for the inverter as well as on its nameplate. If the voltages from the solar panel are below the indicated minimum level, your solar inverter will not start, and you will not get any output to run your load.

There are multiple reasons for low voltage input to a solar inverter, which we’ll discuss in the following subsections.

#3: The Sun is Not Shining Enough

One of the reasons for low voltages is that the sun is not shining enough for solar panels to generate enough voltage to even start the solar inverters. When dealing with low irradiance from the sun, an inverter will not start. Low irradiance can be due to cloudy weather or due to the position of the sun with respect to the solar panels themselves.

There is not much that can be done if the inverter is simply not working due to low irradiance of the sun. Sadly, we already know that this is a significant drawback of installing a solar-powered energy system.

#4: The Solar Panel String is Not Designed Properly

Another cause for an inverter not starting due to low voltage is that the solar energy system has not been designed properly. Solar panels are placed in a series with each other to increase the overall voltage level. An optimal number of series panels in a single string will provide the appropriate voltage range that can keep running a solar inverter in a wide range of solar irradiance levels.

If the solar panels in the series are not sufficient, they will not provide enough voltage unless the sun is shining to its peak level of brightness. As a result, your solar inverter will not be able to get any energy from the panels during low irradiance periods. It will only acquire enough power when the sun is high and radiant enough.

Therefore, the proper design of solar panels in a string is important so that a suitable amount of voltage can be obtained even in times of low irradiance.

#5: The Voltage is Too High

The other side of this coin can also occur when the voltage from the solar energy system exceeds the range of your solar inverter. Mostly, solar inverters have internal protection for not taking further input when they go beyond their maximum voltage limit. In a poorly designed solar string, voltages can go high during maximum sunshine hours, and the inverter will shut down automatically.

Therefore, by properly designing your solar energy system, this issue can be avoided.

#6: Too Much Electrical Load on the Inverter

Solar inverters commonly have protection circuits inside them that turn off the inverter or do not continue electrical output if the electrical load connected to its output is higher than its maximum limit. If the current drawn by the electrical load exceeds the limit of the inverter, it trips the protection protocols in place, and no electrical output will be provided.

Most inverters have timer relays inside of them that try to take more electrical load after some time has passed, but if the load is still higher than the actual limit, it shuts down completely.

Due to this problem, one of the main reasons a solar inverter will not work or not give output is that the connected electrical load is too much high. To clear this fault, turn off the inverter, shed some of the connected electrical load, and start the inverter up again. If the load is within the inverter’s limit, it will provide proper output.

Overheating

Another one of the reasons that an inverter isn’t running or taking a load is that the temperature of the inverter has exceeded the maximum limit. An inverter will sound an alarm or display a warning on its screen when this occurs. The alarms and warning symbols (or signs) will be different for different manufacturers and models of inverters.

#7: Environmental Temperature

Each electrical appliance has a temperature range in which it can be operational. If the environmental temperature is higher than the operating temperature, the inverter will not turn on.

To avoid this overheating problem, your inverter should be installed in a well-ventilated area. If the inverter is installed in a place that does not have proper ventilation, the heat produced by the inverter itself will cause an increase in the temperature of the environment, and ultimately, the temperature of the inverter will increase as well and will shut down.

#8: The Cooling Fan on the Inverter is Blocked

Another reason for an inverter overheating is that the inverter’s fan is blocked or not working. As we have discussed, overheating will cause the inverter to stop working. Therefore, if the fan on your inverter (which is there to cool down the components and provide forced ventilation in the inverter) is blocked due to dust or a malfunction of some sort, this will cause a rise in the inverter’s internal temperature levels. The temperature sensors inside the inverter will sense this rise in temperature and will shut down the inverter to save it from permanent damage or becoming a fire hazard.

To resolve this issue, you have to check the fan physically and remove anything that may be blocking the rotor of fan. You will also need to look for any broken mechanical parts of the fan, too. In the latter case, you simply have to re-install the whole fan.

#9: Electrical Fan Signal is Dead

This problem may arise due to a problem with the inverter’s electrical signals to the fan. In such a case, you will have to consult an electrician or the manufacturer to properly repair this issue.

#10: The Air Filter is Blocked

There is an air filter in most inverters for the fan to be able to blow dust-free air. This filter stops dust and any heavy particles (such as those from oil, etc.) from entering the inverter. If the air filter is old or the inverter is installed in a place that contains heavy particles in the air, the air vents for your inverter will very likely be blocked, and proper air will not be able to reach to the inverter components. This impaired airflow will result in an increase of temperature which, as mentioned, will lead to overheating and other problems.

This temperature rise will result in a shutdown of the entire inverter system. To fix this problem, open the air filter and blow the dust off it. It would also be a good idea to completely change the filter when possible.

Final Words

There are variety of errors that can lead to an inverter shutting down automatically. This article has presented some of those reasons. For any further issues that have not been covered, check the warning signals on your inverter’s display screen and compare any provided information with what’s found in the user manual for your specific inverter. If all else fails, be sure to consult the manufacturer or a skilled professional to help you resolve what may be going on.

See Also:
Do Solar Panels Need to be Replaced?
What Wattage Solar Panel is Required to Charge a 150Ah Battery?
How Many Amps Does a 25-Watt Solar Panel Produce?
WHAT CAN A 50-WATT SOLAR PANEL POWER?
What Size Charge Controller Works for a 200W Solar Panel

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