[RE-wrenches] Tranformless inverter

[August Goers]

Thanks, Dave.

Anyone have clarification on what exact marks to look for in "PV Wire?"

For example, the cables I see on a batch of Suntechs I have in the shop are
listed as "H+S RADOX SMART cable 4.0 mm" on the spec sheet but the only
listing I see on the wire themselves is RHH/RHW-2.

NEC Table 310.13(1) doesn't seem to mention PV Wire.

Thanks again for all your help.

Best,

August

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Dave Click
Sent: Friday, December 10, 2010 1:11 PM
To: re-wrenches at lists.re-wrenches.org
Subject: Re: [RE-wrenches] Tranformless inverter

I believe it's just:
Fusing on the +/-
disconnects break both + and -
Need your modules to use PV wire
labeling per 690.35(F)

Square D discos are UL'd for ungrounded systems- and I just noticed that
there's a June 2010 revision of the Square D disconnect guide. A bit of
clarification since the 9/09 edition I had.
http://ecatalog.squared.com/pubs/Electrical%20Distribution/Safety%20Switches/Solar%20Disconnect%20Switches/3110DB0401.pdf

August Goers wrote:
> Hi Bill and Wrenches -
>
> For ungrounded arrays what specific fusing and or DC disconnect
> requirements are needed compared to grounded arrays?
>
> I'm trying to sort through the code but nothing is popping out at me
> besides what was already mentioned about needing to disconnect both the
> positive and negative lines on the DC side. In SMA's case I'm guessing
> that their new transformerless inverters with integrated DC disconnects
> and fuses may already take of all the requirements?
>
> Best,
>
> August
>
> August Goers
>
> Luminalt Energy Corporation
>
> 1320 Potrero Avenue
>
> San Francisco, CA 94110
>
> m: 415.559.1525
>
> o: 415.641.4000
>
> august at luminalt.com <mailto:august at luminalt.com>
>
> *From:*re-wrenches-bounces at lists.re-wrenches.org
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>
> [mailto:re-wrenches-bounces at lists.re-wrenches.org
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of *Bill
> Brooks
> *Sent:* Friday, October 01, 2010 8:29 AM
> *To:* 'RE-wrenches'
> *Subject:* Re: [RE-wrenches] Tranformless inverter
>
> All,
>
> Transformerless inverters are simply a subset of ungrounded or
> resistively grounded PV systems covered by the NEC in 690.35 since the
> 2005 code cycle. Power-One has been marketing their ungrounded inverter
> in the U.S. for several years now. It was listed by CSA. The
> requirements for ungrounded systems in 690.35 are as follows:
>
> *"Photovoltaic power systems shall be permitted to operate with
> ungrounded photovoltaic source and output circuits where the system
> complies with 690.35(A) through 690.35(G).
>
> -*(A) Disconnects. *All photovoltaic source and output circuit
> conductors shall have disconnects complying with 690, Part III.
>
> -*(B) Overcurrent Protection. *All photovoltaic source and output
> circuit conductors shall have overcurrent protection complying with 690.9.
>
> -*(C) Ground-Fault Protection. *All photovoltaic source and output
> circuits shall be provided with a ground-fault protection device or
> system that complies with (1) through (3):
>
> *(1) Detects a ground fault.
>
> *(2) Indicates that a ground fault has occurred
>
> *(3) Automatically disconnects all conductors or causes the inverter or
> charge controller connected to the faulted circuit to automatically
> cease supplying power to output circuits.
>
> -*(D) *The photovoltaic source and output conductors shall consist of
> the following:
>
> -(1) Nonmetallic jacketed multiconductor cables
>
> -(2) Conductors installed in raceways, or
>
> -(3) Conductors listed and identified as Photovoltaic (PV) Wire
> installed as exposed, single conductors.
>
> -*(E) *The photovoltaic power system direct-current circuits shall be
> permitted to be used with ungrounded battery systems complying with
> 690.71(G).
>
> -*(F) *The photovoltaic power source shall be labeled with the following
> warning at each junction box, combiner box, disconnect, and device where
> the ungrounded circuits may be exposed during service:
>
> WARNING
>
> ELECTRIC SHOCK HAZARD
>
> THE DC CIRCUIT CONDUCTORS OF THIS
>
> PHOTOVOLTAIC POWER SYSTEM ARE
>
> UNGROUNDED AND MAY BE ENERGIZED
>
> WITH RESPECT TO GROUND DUE TO
>
> LEAKAGE PATHS AND/OR GROUND FAULTS.
>
> -*(G) *The inverters or charge controllers used in systems with
> ungrounded photovoltaic source and output circuits shall be listed for
> the purpose.
>
> We now have several products newly on the market to include on the list
> such as the SMA and Exeltech products. Ungrounding the array requires
> additional fusing and disconnects, but the most significant difference
> is that the module wiring and all external cable must be PV Wire/Cable.
> Therefore only modules with PV Wire/Cable can be used in these systems.
> You must confirm from the manufacturer that they have made the switch.
> Hopefully all manufacturers will be installing PV Wire/Cable soon so
> that this will not be a problem anymore.
>
> It is a good call to use up your USE-2 and order PV Wire/Cable from now
> on.
>
> Bill.
>
> *From:*re-wrenches-bounces at lists.re-wrenches.org
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>
> [mailto:re-wrenches-bounces at lists.re-wrenches.org
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of
> *Exeltech
> *Sent:* Friday, October 01, 2010 6:39 AM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] Tranformless inverter
>
> Transformerless grid-tie inverters are permitted under the National
> Electric Code as of 2008. The Nationally Recognized Testing Laboratories
> (UL, ETL/Intertek, CSA, etc.) took a while to develop the testing
> procedures for testing to UL1741, which was the basis for most of the
> delay.
>
> SMA isn't the only company with transformerless grid-tie inverters. I
> know of one American manufacturer with transformerless models on the
> market as well.
>
> Transformerless inverters are smaller, much lighter, and tend to be more
> efficient than transformer-based units. No transformer also means lower
> product cost, and less shipping expense. Win-win-win.
>
>
> Dan
>
>
> --- On *Fri, 10/1/10, Drake /<drake.chamberlin at redwoodalliance.org
> <mailto:drake.chamberlin at redwoodalliance.org>>/* wrote:
>
>
> From: Drake <drake.chamberlin at redwoodalliance.org
> <mailto:drake.chamberlin at redwoodalliance.org>>
> Subject: Re: [RE-wrenches] Tranformless inverter
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org
> <mailto:re-wrenches at lists.re-wrenches.org>>
> Date: Friday, October 1, 2010, 6:58 AM
>
> I also received this advertisement. Previously I had investigated the
> smaller SMA transformerless inverters, and was told that this type would
> not be allowed in the US until the 2011 code. Has the ban been lifted?
>
>
>
> At 12:52 AM 9/29/2010, you wrote:
>
> Wrenches:
>
> I received an advertisement from a distributor that SMA is now shipping
> 8, 9 and 10 KW transformerless inverters. Don't these require double
> insulated PV wiring and no connection to ground on the AC side? It's
> been too long since this subject last crossed my desk and I want to
> refresh my memory on the specifics.
>
> William Miller
>
>
> _Please note new e-mail address and domain:
>
> _William Miller
> Miller Solar
> Voice :805-438-5600
> email: william at millersolar.com <mailto:william at millersolar.com>
> http://millersolar.com <http://millersolar.com/>
> License No. C-10-773985
>
>
>
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