[RE-wrenches] AEI Solaron Inverters - DC Grounded or Ungrounded

[Matt Lafferty]

Thanks Bill. It's the "Claim Dance" that concerns me.
 
I sent an inquiry to AEI Tech Support asking about the grounding status of
the Array during operation. It was a simple question: Regarding AEI Solaron
PV Systems: Is the PV array normally grounded during operation?

I would be more than happy to share the response except for the little "you
might get sued" notice at the bottom of their response... 
 
<Start Quote>
This message, including any attachments, may contain information that is
confidential and proprietary information of <REDACTED>, Inc. The
dissemination, distribution, use or copying of this message or any of its
attachments is strictly prohibited without the express written consent of
<REDACTED>, Inc. 
<End Quote>
 
Their response is that the arrays are NOT ground referenced during
operation. Specifically that the array is floating during operation. The
neutral conductors are grounded when the system is not operating. 
 

This information suggests that 690.35 is in play. All of the AEI system
designs that I have seen only have OCP & Disconnecting means in non-neutral
conductors. How did that happen? These things have been in the field now for
3 years. How does it still keep happening?
 
In light of the information above, do you (or anybody) still think the
neutral conductors should be marked white?
 
I am not opposed to bi-polar or floating arrays. Frankly, I believe that
properly designed and installed floating arrays are inherently safer than
grounded arrays. My primary concern is that some/most/all of the AEI systems
going in these days may not be properly designed and installed, per 690.35.
 
I have additional concerns around whether or not the arrays are actually
operating at >600V, which would require >600V fuses, disconnects, cables,
modules.... You get the picture. I have personally done some testing (on
systems with inverter-integral PV tie) which indicates that the arrays are
NOT operating at >600V. I have questions about whether or not my Fluke picks
up actual voltage in a high-freq switched array, but I can state
conclusively that I never saw voltages >600V in any portion of the arrays
during operation. (Read this as "I'm less concerned about this issue than
the previous") I have NOT performed these same tests on a system equipped
with the Remote PV Tie, and am reserving an opinion on that until I do or
someone can conclusively demonstrate that system voltage is <600V.
 
I have followed up with a request for AEI's position on the 690.35 matter as
well as their recommendation(s) for marking of the neutral conductors. I
guess I will have to follow up with a request to disseminate, too.
 
Opinions & thoughts?
 
-Matt
 
  _____  

From: Bill Brooks [mailto:billbrooks7 at yahoo.com] 
Sent: Monday, May 03, 2010 5:17 PM
To: gilligan06 at gmail.com; 'RE-wrenches'
Subject: RE: [RE-wrenches] AEI Solaron Inverters - DC Grounded or Ungrounded



Matt,

 

They claim to use a bi-polar array with 600Vdc per pole. All bipolar arrays
must be grounded, so they must be grounded. They claim to be grounded
through the ac service transformer while operating. They are fundamentally
similar to many ungrounded designs. So, it IS grounded during operation
every time the transistor closes, which is very fast, so they don't spend
much time ungrounded during operation-maybe never because they are operating
on 3 phases. The neutrals would have to be white.

 

Bill.

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Matt
Lafferty
Sent: Monday, May 03, 2010 1:28 PM
To: RE Wrenches
Subject: [RE-wrenches] AEI Solaron Inverters - DC Grounded or Ungrounded

 

Wrenches,

 

Can anyone DEFINITIVELY tell me whether the DC systems on AEI Solaron based
plants is grounded or ungrounded during operation? 

 

Have you tested your theory in the field? What marking requirements do you
suggest for the neutrals?

 

Thanks!

 

Matt Lafferty

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20100504/51f2f55f/attachment-0004.html>