AFCI breaker tripping ONLY WHEN grid tie solar system active

[aaronrnelson]

I had solar installed professionally 3 years ago. The home is 10 years old and has 3 AFCI breakers for bedrooms. One AFCI circuit was hardly used. A new mini fridge was plugged into the rarely used circuit. The mini fridge (60 watt) now causes the AFCI breaker to intermittently trip. I moved the mini fridge to the other 2 AFCI circuits and I experience zero problems.

I bought and installed a new AFCI breaker, but the NEW AFCI breaker continued to INTERMITTENTLY trip with mini fridge. Over the weeks I noticed a pattern develop, the AFCI would not trip at night, but mostly during the day when the mini fridge cycled on.
I decided to turnoff my solar, and it was off for a few days, during those days the mini fridge DID NOT trip the one AFCI circuit in question. I have a double pole 25 AMP breaker installed inside the power panel that connects my solar grid tie system. Just by flipping off this breaker, my AFCI circuit works as intended.

Any ideas on how to fix this problem? The solar company installed the system over 3 years ago and I'm going to contact them about the problem. But I'm hesitant that they won't try to solve the problem. If it's an easy fix I would try and solve the problem myself, I just don't know where to begin. I also would like to be educated on this problem so I can have some leverage over the solar installers, who I believe caused this problem to happen.

 

[newfutile]

Solar inverters put out a modified sine wave which is slightly higher than the grid voltage, it sounds like protective device thinks that the compressor in the fridge starting on the solar (modified sine wave) is an arc and disconnecting !

 

[amartinsolar]

I had solar installed professionally 3 years ago. The home is 10 years old and has 3 AFCI breakers for bedrooms. One AFCI circuit was hardly used. A new mini fridge was plugged into the rarely used circuit. The mini fridge (60 watt) now causes the AFCI breaker to intermittently trip. I moved the mini fridge to the other 2 AFCI circuits and I experience zero problems.

I bought and installed a new AFCI breaker, but the NEW AFCI breaker continued to INTERMITTENTLY trip with mini fridge. Over the weeks I noticed a pattern develop, the AFCI would not trip at night, but mostly during the day when the mini fridge cycled on.
I decided to turnoff my solar, and it was off for a few days, during those days the mini fridge DID NOT trip the one AFCI circuit in question. I have a double pole 25 AMP breaker installed inside the power panel that connects my solar grid tie system. Just by flipping off this breaker, my AFCI circuit works as intended.

Any ideas on how to fix this problem? The solar company installed the system over 3 years ago and I'm going to contact them about the problem. But I'm hesitant that they won't try to solve the problem. If it's an easy fix I would try and solve the problem myself, I just don't know where to begin. I also would like to be educated on this problem so I can have some leverage over the solar installers, who I believe caused this problem to happen.

Hi Aaron, I'm a branch operations supervisor for a solar company in the Midwest, and we have run into a similar issue with one of our installs here. The project in question is a new construction home with AFCI breakers. The solar is tied to the general service meter socket with compatible lugs and not back feeding the service panel.

Breakers started tripping almost as soon as the day after commissioning the system with the utility, and the homeowner noted that the two breakers that frequently tripped were the upstairs kitchen (fridge) and downstairs wine bar (minifridge). It also happened during the day only. Upon the homeowner notifying us of this issue our electrician replaced the breakers, but it did not fix the issue.

Suspecting that it may be a frequency issue, we contacted the inverter manufacture (Enphase) level 2 tech support and asked that the microinverters settings were updated from leading to lagging. We believe that the switching it to lagging would ensure that it wouldn't take precedent over the utility grid frequency. This reduced the frequency of breakers tripping but unfortunately did not eliminate the issue. After calling the utility they noted that with construction nearby in the area other homeowners with GCFI and ACFI were experiencing periodic tripping as well. So we now suspect there are multiple factors at play. Sharing this information to anyone else who may have the same problem!