How can I tell if my solar inverter is working?

First, let’s start with the basics. A solar inverter (PV inverter) receives the variable direct current (DC) output of photovoltaic cells and converts it into alternating current (AC) - the electricity you find in your regular house plug - by also connecting to your electric panel.

If you have a solar powered home and you lose electricity, there could be something wrong with the inverter. This is usually a large device (often black or gray color) installed on or inside your home.

To make sure it is functioning properly, you should check your solar panels first, making sure they are free of debris or something else that blocks sunlight from reaching them.

If sunlight is hitting the panels, the inverter should be working. You make sure of this by paying attention to the numbers and other information being displayed on the screen. 

Error messages

Almost all inverter models have a display board with messages and lights to indicate there is a problem with the system. The color of these lights may be different, and whether they are intermittent (blinking) or solid could mean different things. Check your model’s manual for full details.

But generally speaking, a solid green light means the inverter is functioning properly and your solar panels are generating electricity. If the light is red during daytime hours, the system is not working. Remember that it will also show a red light at night or evening, when it is on sleep mode. 

If the inverter itself shows an error message and it’s not working, call the solar system installer and report the issue so they can do an on-site inspection to determine how to fix it. Most components of a solar power system come with a long warranty and you should be covered. 

If you have a monitoring equipment, check current and historical generation measurements for any notable change in electrical generation. 

Problems

Inverters may shut down due to a number of reasons. Perhaps it was sized incorrectly when installed and can’t handle the energy load being delivered by your solar panels. 

It may also be due to a grid fault where the voltage is too high or too low. Or it could be that the circuit breaker for the inverter has tripped. 

As with any machine, solar power inverters are sensitive to high temperatures. Overheating may be behind the trouble. Maybe the inverter is located inside a building or is exposed to very high temperatures with poor ventilation and tends to overheat.

Some models come equipped with fans or other type of cooling mechanism and those systems malfunctioned. 

There’s also the possibility that high humidity (even water damage) may cause problems. Humidity has been shown to contribute to about 20% of electronic failure. Same thing with water damage, which may cause corrosion of the inverter components. 

Same thing with exposure to chemicals, such as the ammonia generated by cows in a farm. Ammonia is a corrosive and an inverter placed in a location with high concentrations of it may be exposed to corrosion of its copper alloys. Other solutions or chemicals could have the same effect.

Exposure to vibrations may also be the culprit of inverter failure. Any surface where a solar power inverter is mounted should be free from vibrations.

There’s also the possibility of an “isolation fault,” which is caused by a short circuit between various parts of the solar power system. The inverter may report an “isolation alarm.”

Short circuits can occur for a number of reasons, such as moisture or damage to cables, faulty installation, poor connection of the DC cables to the panel, or other factors. 

The solution may be as simple as resetting the inverter; some models do that on their own. If it doesn’t restart on its own, a service team much be called to check it on-site. 

Sometimes it may require you to shut down the system manually. 

To keep your inverter working at optimum, experts recommend having it checked annually by your solar installer to perform some maintenance. He/she should inspect and clean the equipment thoroughly, tighten any loose connections, and also do an analysis of electric production to make sure the solar panels and all other components are working properly. Depending on your contract, these visits may or may not be included in your agreement.  

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