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Modern inverters have built in overload protection, so the worst thing that will probably happen is the system will not run. Fortunately there are ways to fix an inverter overload, and you can try these solutions first before calling for customer support.
Shut the inverter off and reduce the appliance load. Turn the inverter back on and if the overload message is still there, use the reset button. If there is no reset button, turn off the system and wait a few minutes before turning it on again.
What Causes Inverter Overload?
Any of the following may result in an inverter overload.
- Faulty inverter. There is a problem with the internal circuitry.
- Cabling issues. The cable wiring for the appliance and inverter are loose, frayed or both.
- Appliance problem. The appliance refuses to run on the inverter because it is damaged.
- Excessive power. The appliance running watts or surge watts is beyond the inverter capacity.
Any of these problems can occur regardless of the inverter size or type. And now that we know what the causes are, we can start diagnosing the problem and come up with a solution.
Note: these solutions are for inverters only. Inverter / chargers have different components and the suggestions here may not be applicable.
These three tests should be done in order. We also assume that you are comfortable handling cable wires and electrical power. Some knowledge of inverter installations will help.
Test the Inverter
First you need to rule out the possibility that the inverter is the cause.
- Shut off the inverter.
- If the inverter is connected to a battery bank, check the battery. Is there enough charge? Are the batteries properly maintained?
- Check if the inverter and battery cable is secure. Give it a light tug.
- Clean the batteries. Pay close attention to the terminals and ensure there is no dirt or rust buildup. The Schumacher Battery Terminal Cleaning Brush will get the job done.
- If you have not already done so, disconnect every appliance. Shut off the circuit breakers or unplug the appliances from the sockets.
- Once the appliances have been removed, check if the appliance wattage is within the inverter capacity. Look up the wattage for each appliance or use this guide.
- Turn on the inverter. If the system says it is still overloaded, press and hold down the reset button. Wait for the system to reset.
- If there is no reset option, turn off the inverter. Wait a few minutes and turn it on again. But if the condition persists, the trouble is with the inverter internal components.
A faulty internal component can cause a problem like an inverter being overloaded without any load connected to it. In this case you have to contact the manufacturer or installer and have the inverter repaired or replaced.
Test the Appliance
If the inverter is not the cause, you can test the appliances. Follow these steps.
Note: A 3000 watt inverter with a 90% efficiency rating will use 3200 to 3300 watts if it runs on a full load. If the battery bank has insufficient power the system might display all kinds of error messages or refuse to run. Always factor in efficiency when calculating inverter capacity.
- If you have not done so already, add up the total appliance wattage. Keep in mind that inverters will use more power than the appliance total wattage due to inefficiency.
- Connect one appliance at a time to the inverter if you are not sure of the total wattage. Start with something small like a mobile charger or fan to ensure the inverter can handle it.
- Make sure the surge watts does not surpass the inverter capacity. A refrigerator might use only 800 watts a day, but it might need up to 1800 surge watts.
- If the appliance surge watts is higher than the inverter peak output, the system will overload. Both the running and surge watts have to be within the inverter capacity.
- If an appliance refuses to run, try it on a regular AC power outlet. If it does not run, the problem has nothing to do with the inverter, but with a short circuited appliance.
- Repeat this for every appliance that you suspect may have short circuit issues.
Test the Cable
The last test that you can do is check the cables. Just like appliances and the inverter, it is possible for cable wires to be overloaded.
All you need to do is unplug the appliance. If there is a problem with the inverter cable wire an error message will pop up. If the cable is frayed, replace it immediately. If the system uses 5 AWG we recommend the InstallGear 10 ft Power Inverter Cables.
What Happens if an Inverter is Overloaded?
An older inverter might malfunction or even damage the appliances if it is overloaded. But with a modern inverter, the system will either not start or just stop. The inverter might also produce a lot of noise.
If the load exceeds the capacity, the inverter will refuse to run. If the system is already running and you add load that exceeds its capability, the system will halt.
The inverter will either restart or shut down. Some inverters will only turn on if the load is reduced. These are safety features built into most inverters, from the portable units to the large ones.
Some inverters will display an error code indicating it the load is above capacity. In some cases it will just stop running. At any rate that should be enough of a sign that the system is maxed out and you need to fix it.
Inverter Overload FAQ
Because there are many possible reasons why an inverter will get overloaded, this FAW may prove useful. What you might be experiencing may be answered in the questions below.
Will overloading damage the inverter?
While inverters have built in protection, you should fix the problem as soon as possible. Repeated overloading could damage the inverter and appliances.
Solar inverters today will not run if the load exceeds its capacity. However, a 2000 watt inverter with a 1300 watt load will be overloaded if you add another 1400 watts. This will force the inverter to stop running or attempt to restart.
The worst case scenario is the inverter will just keep restarting until it crashes. This is why you should reduce the load immediately when the overload message appears.
My inverter does not have a reset button. What do I do?
Just turn off the power and wait a few seconds to turn it back on. If you want to do a hard reset, turn off the system and unplug the AC power supply, the solar panel disconnect system and the main electrical panel. After 30 seconds, reconnect and turn on the components in the reverse order you shut it off.
My inverter is noisy. Is it a sign of overloading?
Most inverters produce a low humming sound, but it is barely discernible. If your inverter is making a lot of noise it is probably due to the cable being too small. If the wire is not the proper size the voltage will drop and generate noise.
My inverter is showing overload without load. Why?
This is due to an internal problem with the inverter. A component is malfunctioning and needs to be repaired or replaced. Before you call customer support, reset the inverter a couple of times. If the inverter has been overloaded with appliances, it might take a reset or two to refresh the system.
Once an inverter displays an overloaded message, you need to reduce the load. However the effect might not register immediately, so a reboot or reset is required. If it does not work, you have to get the inverter repaired.
Why is my inverter tripping?
This is another indication of overloading. An inverter tripping, shutting off or repeated start/stop are signs there is too much power coming in. The excess current is more than the inverter can handle.
My inverter is not overloaded but the system is not running properly. Why?
If the inverter is not damaged and the appliance load is within the system limit, the problem lies in the cable wires. As a general rule, always use the thickest and shortest cable for inverters, batteries, charge controllers and solar panels. These wires are the best in transmitting power and provide the least amount of resistance.
The modern solar inverter comes with several safety features so an overloaded system will likely not cause a serious problem. By following the simple DIY tips provided here, you can remedy any overload problems and get the system running again.