<div dir="ltr">I installed 2 10kW 208V powerone inverters this summer and both failed. The first one failed right out of the box and the second made it a few months. We were hired just to install the system by a local firm that designed and sold the system and have had a bear of a time getting paid from anyone. <div>
<br></div><div>Jesse</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, May 8, 2013 at 12:38 AM, <span dir="ltr"><<a href="mailto:don@energysolarnow.com" target="_blank">don@energysolarnow.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><span style="font-size:10pt;font-family:Verdana"><div>Hi all- While I have not had the failure problems noted with microinverters, PowerOne inverters have recently given me a big headache. Installed their 6kW model last November that failed in a month. They replaced it under warranty, no problem no reimbursement. Then the replacement failed in March. Again replaced, no problem. But that's the problem-- there was no indication from the inverter of why it failed. When the replacement inverter that was installed in March failed in April, they declared it out of warranty and made me pay nearly $900 for repairs. This is less than 6 months from initial installation. <br>
</div><div>All the failures occurred after rainy weather. This time I bought megaohm meter and checked the wiring. There was a nick in the insulation where a negative DC home run pulled around a rail corner, with a small but noticable burn spot. This did not show up with a standard meter check, but it did with the megger and some watering from a hose. OK, so there is an intermittent ground fault. With a transformer inverter that would just be a blown fuse with a ground fault error message. But it seems this inverter will self destruct with a ground fault. No error message or any other indication that even PowerOne would or could relate before sending 3 replacements. </div>
<div>The Tigo monitors indicated that each inverter failure happened at
morning power-up, with minimal solar current. Oh, and having Tigo
monitors in the system but not on the one-line drawing was PowerOne's
nominal excuse for canceling their warranty. They posted a document on their website dated March 10,
right after the second failure, to the effect that when using Tigo
monitors you must disable the inverter MPPT scan so they don't fight.
But didn't tell me, or apparently their tech staff....</div><div>The post-mortem on the last two inverters (performed well after the replacements were sent) indicated over-current in the IGBTs. So where is this lethal current coming from? There are only two strings, one each into this dual channel inverter. There is not enough solar current to kill it even in broad daylight. But a morning power-up failure can only mean some AC input surge current sneaks through the ground fault and into the DC inputs. Sounds like a design flaw to me... There should not be anything that can kill an inverter other than over-voltage or over-current; and that would kill it quick, not a month or months later after a rain.<br>
</div><div><br></div><div>Can anyone suggest a possible failure mechanism? Surely not the dreaded electrolytic caps-- the inverter is mounted under a dry eve.<br></div><div>In general, how are transformerless inverters protected internally from external ground faults? </div>
<div>And the obvious question is: how could anyone trust a company with this kind of warranty service?</div><div>Thanks</div><div>Don Barch</div><div>Energy Solar<br></div><div><br></div><div></div><blockquote style="padding-left:8px;font-size:10pt;margin-left:8px;font-family:verdana;border-left:2px solid blue">
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<br>
Message: 13<br>
Date: Tue, 7 May 2013 09:03:13 -0600<br>
From: Troy Harvey <<a href="mailto:taharvey@heliocentric.org" target="_blank">taharvey@heliocentric.org</a>><br>
To: RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>><br>
Subject: [RE-wrenches] Dual Channel Inverters<br>
Message-ID: <<a href="mailto:1F568BAC-8D04-4E09-BC44-9090C147F0B5@heliocentric.org" target="_blank">1F568BAC-8D04-4E09-BC44-9090C147F0B5@heliocentric.org</a>><br>
Content-Type: text/plain; charset="windows-1252"<br>
<br>
Since we stopped using micro-inverters due to the high failure rate, network problems, difficultly in replacement ? I've been using the power-one inverters a bunch because the dual channels solve most of tricky issues like different roof aspects, shading, and uneven strings.<br>
<br>
However, they are limited to 6kW, which is only mid sized in todays world. I'm constantly having to design 7-12k systems in residential applications all the time. Any other dual channel inverts of the market for 240VAC? I remember back a few years ago that sharp had a 3-channel inverter. Doesn't look like it is still around.<br>
<br>
thanks,<br>
<br>
Troy Harvey<br>
---------------------<br>
Principal Engineer<br>
Heliocentric<br>
<a href="tel:801-453-9434" value="+18014539434" target="_blank">801-453-9434</a><br>
<a href="mailto:taharvey@heliocentric.org" target="_blank">taharvey@heliocentric.org</a><br>
<br>
<br>
</div>
</blockquote></span></div>
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