I think I just read that SMA has changed their long-standing 15A per string fuses to 20A.
You might look to see if it applies to existing systems. Hope it helps. Glenn From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jason Szumlanski Sent: Thursday, February 06, 2014 12:50 PM To: RE-wrenches Subject: [RE-wrenches] DC Series Fusing in inverters SMA inverters typically come with 15A KLKD fuses pre-installed. I have seen a bunch of blown fuses recently (after cold weather)... It seems that some dealers are just assuming the 15A fuse is okay for series strings and not doing the calculations. I've been finding quite a few Evergreen systems or parallel connected two-string SunPower systems that should have 20A fuses per NEC 690.8. The problem does seem to be worse where inverters are exposed to direct sunlight, presumably from fuses that no longer meet their ampacity rating due to heat. Anyone else run into this frequently? Jason Szumlanski Fafco Solar
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