[RE-wrenches] AFCI trip on metal roof

[Drake]

Hi August,

The inverter is an Sunny Boy 7700TL-US-22 with 
REC 280 TP modules. The array and roof are grounded.

There are large compressors on the system for 
heat pump and A/C.  The array is on an estimated 
2600 sq ft metal roof. The system had no issues 
for months after the installation and then the 
arc fault device started tripping and wouldn't 
stay reset. The system was operating normally again by the time we got there.

Drake

At 06:16 PM 3/23/2016, you wrote:
>Hi Drake,
>Â
>What model SMA inverter(s) and modules do you 
>have? We had one case where a MC4 connector 
>under the array was not making good contact. It 
>was not seated properly when the installer made 
>up the connector and the arc fault sensor in the 
>inverter did its job. We had another site where 
>some electrical noise on the AC side, presumably 
>a sump pump, caused the issue and we could not 
>solve it so had to switch to another inverter 
>manufacturer. There were other cases where the 
>impedance or other electrical characteristics of 
>the solar modules where the likely culprit.
>Â
>Is your roof and array totally equipment grounded?
>Â
>Best,
>Â
>August
>Â
>From: RE-wrenches 
>[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Drake
>Sent: Wednesday, March 23, 2016 2:08 PM
>To: 
><mailto:RE-wrenches at lists.re-wrenches.org>RE-wrenches at lists.re-wrenches.org
>Subject: [RE-wrenches] AFCI trip on metal roof
>Â
>Hello Wrenches,
>
>We have a project with an array on a large metal 
>roof. The AFCI has been tripping. Investigating 
>the system, there is no evidence of any arcing: 
>the wiring and connections are all very tight.
>
>SMA tech support says it is likely that the 
>nuisance tripping comes from electrical noise 
>getting picked up by the large metal roof.
>
>What has been your overall experience with 
>nuisance tripping of arc fault protection? What 
>were the suspected causes? What was the solution?
>
>Thanks,
>
>Drake
>
>Drake Chamberlin
>Athens Electric LLC
>OH License 44810
>CO License 3773
>NABCEP Certified Solar PV
>740-448-7328
><http://athens-electric.com/>http://athens-electric.com/
>
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