FW: Mis-statements regarding Microsine, UL clarifications [RE-wrenches]

[Bill Brooks]

Wrenches,

This is a message from my colleague, Jeff Newmiller, who keeps the list of
eligible inverters and modules for the CEC.

Bill.


-----Original Message-----
From: Jeff Newmiller [mailto:jeffn at endecon.com]
Sent: Friday, December 14, 2001 11:30 PM
To: RE-wrenches at topica.com
Subject: Mis-statements regarding Microsine, UL clarifications


I work with the CEC to maintain their eligibility lists for PV modules
and inverters.  I've known of this list for awhile, but I don't turn
wrenches very often :) so I haven't followed it closely.
However, I noticed some mis-statements in a recent message, and felt
I could clear up some confusion.

Todd Cory, Bald Mtn. Solar wrote:
> All this hoo-ha about the SW's now not being acceptable for grid tie
> applications makes me wonder about the old micro-sines... has there
> been and "recall" on their application as well?

No.  Nor are any other Xantrex models affected by this.

a) There has been no "recall" on any application, assuming you are
   referring to CEC buydowns.  There is a suspension, pending
   resolution of certification conformance concerns.

b) Microsines were removed from the CEC list in March 2001 because
   they could not pass the final version of the UL 1741 requirements
   and the grace period had ended.  As far as I am aware, no current
   production should have UL marks.

c) A utility interconnection inspector could choose to accept
   Microsines for interconnection in the US, but because
   they don't conform to the current UL1741 standard they very likely
   wouldn't.  A building inspector most likely would accept
   units with UL labels, because there are no safety alerts
   on them.  However, if they are already installed in an approved
   system, they are grandfathered in either case.

sunw- at cheqnet.net answered:
>
> Hey Todd,
>
> Shouldn't have any effect. Trace/Xantrex never manufactured
> them. If I have the story straight, they discontinued offering
> the micro-sine because it wasn't UL listed and they didn't want
> to invest in getting them listed.
>
> Kurt Nelson

Trace had arranged to manufacture them under license from
NKF KABEL, B.V. in The Netherlands, and had written appropriate
documentation for their sale in the US.  I don't know how many
were actually produced in the U.S. (zero, you say?), and have
no details as to why they did not modify them to meet the final
version of UL1741.

"Todd Cory, Bald Mtn. Solar" <todd- at jps.net> then replied:

> Interesting as I know of one legally utility inter-tied
> system in our local area that uses microsines, guess they
> (PP&L) doesn't care whether things connected to "their grid"
> are UL approved or not... wonder what all the fuss is over
> the SW then?

I would assume those Microsines are grandfathered.

The fuss is that UL says SW doesn't appear to meet all the current
requirements for grid-tied operation. Since UL handles grid-tie
capable and off-grid-only certification differently, the
Listing has been withdrawn because it is a grid-tied certification.
UL could have required a recall if the situation were serious
enough... note that they did not.

Inspectors and utilities may evaluate the situation on a
case-by-case (or a more broad) basis.... but the CEC Guidebook
states that inverters must be Listed by a Nationally Recognized
Testing Laboratory to qualify for buydown funds.  The situation
appears to be resolvable, so CEC action is suspended rather than
terminated.

Dan Whigham then added:

> The manufacturer had them UL approved to plug into the wall using a cord
> and GFI outlet.
>
> Regards,
>
> Dan Whigham
> South Carolina Solar
> www.scsolar.com
> 803-802-5522

Seeing this stated by a Xantrex dealer is very disappointing.
The documentation clearly states "Terminals, lugs or splices are
required for hook-up of the AC wiring."  Wall plugs are not
mentioned, and using them is not approved.

Some valid technical arguments for "module inverters" are that
they help you to avoid the I-V curve shape mismatch problems and
if an inverter fails you don't lose all the output from your whole
array.  Aonnecting them with wall plugs is not an acceptable marketing
suggestion.

----------------------------------------------------------------------
Jeff Newmiller, Research Engineer                  Endecon Engineering
mailto:jeffn at endecon.com                        http://www.endecon.com
----------------------------------------------------------------------

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