I'm trying to resolve an intermittent frustrating problem with and Enphase IQ system. There are three AC Branch circuits of 9 microinverters each coming into an Enphase AC combiner.
What has been happening is one of the BR220 branch circuit breakers and the combine CH240 breaker in the main backfed load center have been tripping simultaneously. It has happened about four times in the last 6 months. It was always the same branch circuit breaker, so we kept investigating that string, checking the junction box, trunk cable, and cap, etc. Finally we swapped out the BR220 breaker. Fast forward 4 weeks, and we got another call. This time a different branch circuit breaker and the main breaker tripped simultaneously. We checked that branch circuit and could not find any fault. It seems unlikely that two branch circuit breakers would be faulty, so we have now switched out the CH240 main breaker in hopes that it is the culprit. I'm not totally confident in this resolution and I have my fingers crossed. If that doesn't work, does anyone have any suggestions on another diagnostic step? These intermittent problems are a major hassle. One thought I had was to switch to a supply side interconnection with a fusible disconnect. Maybe the intermittent fault would blow one of the two line fuses so at least I could narrow it down to which line the fault is on if there is in fact a fault. I have experienced two other tripping breaker issues with Enphase systems in the past. Neither of them were systems I installed. One turned out to be branch circuits that were not properly paired up and landed on different breakers. Another time we had an inverter with an internal fault which eventually"blew up" with a loud popping noise and smoke billowing out of it. That happened after resetting a trip breaker multiple times. This case seems to be unrelated to those issues. I'm perplexed. Jason Szumlanski Florida Solar Design Group
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