[RE-wrenches] What would cause a slow string voltage "bleed" and arc fault light

scot.arey at solarcentex.com scot.arey at solarcentex.com
Tue Jul 22 02:46:01 PDT 2014


Situation: SMA5000TL with two strings of Rensola 260s was functioning perfectly fine.  We had to remove system for customer to repair roof after nasty hail storm (no damage to modules).  Reinstalled system and all commissioned fine.  Week later - customer calls and says Arc Fault light is on.  Team goes and believes a not fully tight wire at fuse at roof-top Soladeck fuse holder not tight… resolved… no - one week later another call and same light.


Troubleshooting: take top module covering Soladeck roof enclosure off and check strings individually. We open the strings at the microfuse individually (ungrounded system, both positive and negative conductors are fused.)The string not on seems to have a small but present small voltage that quickly bleeds down to millivolt levels.  Check all connections, briefly think that the single removed module might be damaged but check Voc and Isc and check off as functional.  Two strings enter the DC disconnect separately and make 414 volts +/- a very small level.  But the A string bleeds off voltage approximately 10-12 volts if the voltmeter is left on the terminals for 20-30 seconds instead of taking a quick, “point” reading.


Question:  what would cause this slow bleed and could this be why I don't see an arc fault light immediately but only have a few days?






Howard "Scot" Arey

Solar CenTex
254-300-1228

"Use the Texas Sun!"
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20140722/9d8009dc/attachment-0001.html>


More information about the RE-wrenches mailing list