[RE-wrenches] Line Side Feed In and Disconnects

Fri Mar 13 18:53:32 PDT 2009

Yeah, Welcome to the World of the Feed In Tariff!

Oh Well! At least we have business.

Wayne Irwin, President

Pure Energy Solar International Inc. 

Lic # CVC56695 

Wayne at PureEnergySolar.net 

http://pureenergysolar.net 

352 377-6527 Office
352 336-3299 Fax
352 316-1637 Cell

From: sjohnson at lightwavesolarelectric.com
To: re-wrenches at lists.re-wrenches.org
Date: Fri, 13 Mar 2009 20:46:58 -0400
Subject: Re: [RE-wrenches] Line Side Feed In and Disconnects

Re: [RE-wrenches] Line Side Feed In and Disconnects

Oh brother, that 230.72(A) is a nightmare.

TVA and their 160 distributors are in the process of going to a
line side feed in tariff from a load side production credit.

Actually they plan on letting the distributor offer either or
both options at their discretion.

I’m laying out  a job today with a standalone rack
mounted 100 amp 3 phase 480 volt disconnect and feed thru meter out by the
padmount transformer.

The existing service is 2500 amp and because the service was installed
under the building slab (new building) there is no outdoor disconnect.

This means we would have to dig up a 2500 amp service and turn
it up out by the padmount transformer. FORGET IT!  That’s a huge
switch with 4 four inch conduits full of 400 MCM going in and going out of that
switch. 

This is onerous.  Onerous I tell you! 

I would submit that the exception to 230.72 (A) for water pumps
be amended to add clean renewable PV systems.

John Wiles are you out there?

Steve Johnson

LightWave Solar Electric

Nashville, TN

From:
re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org]
On Behalf Of David Brearley

Sent: Tuesday, March 10, 2009 12:28 PM

To: RE-wrenches

Subject: Re: [RE-wrenches] Line Side Feed In and Disconnects

Wayne,

As you suggested, because this is a new service, a PV service disconnect is
required. The question of whether a second disconnect is required, a new
disconnect for the main service, is a Code issue, as far as I can tell.
It is also an interpretation, but I’ll get to that later.

It just so happens that the June/July issue of SolarPro magazine will
have an extensive article on making PV interconnections. The authors are Ryan
LeBlanc and Tarn Yates from SPG Solar. From their article, here are some Code
articles that apply to selecting and locating a disconnect for a line side
connection:

230.66 – Disconnect shall be listed for use as service equipment.

230.70(A)(1) – Disconnect shall be installed at a readily accessible
location.

230.72(A) – All service disconnects shall be grouped together.

The last article is no doubt the one that the AHJ is referencing in this case. 

The reason I feel that this extra expense and effort is an interpretation, as
much as it is a Code issue, is that you could make a load side
connection and still have the math work for the feed-in tariff program and for
the revenue metering. 

How is that? 

Well, a meter on the inverter output circuits will read the total PV kWh for
the feed-in tariff. A bi-directional meter for the revenue meter will read
in-flow from the utility and out-flows to the utility. The difference between
total PV kWh and the out-flow-kWh are the PV generated kWh that the customer
used on site rather than export to the utility. Right? Whatever PV generated
energy is not exported to the utility is used on site.

So for billing purposes the customer is charged as follows:

Total kWh for billing = In-flow kWh + (feed-in tariff kWh – out-flow kWh)

Theoretically, this can also be implemented affordably by the utility: move the
exiting revenue meter to the PV system; add a $100 bi-directional meter to the
original meter can. Finished. 

Making a line-side connection is often difficult and expensive, especially when
you now have to add a new service disconnect for the facility. At least in
theory, it is also dangerous; the fault-currents there are higher. You have
these implementation issues on the one hand. On the other hand you have a
spreadsheet, or a one-time fix the the utility’s billing software. 

So I think the utility is making this more onerous than they need to.
Especially for small generators, the cost of this service upgrade will kill the
deal. The utility probably isn’t interested in this solution, but we can
still dream of the perfect fix.

David Brearley, Technical Editor

SolarPro magazine 

NABCEP Certified PV Installer ™

david.brearley at solarprofessional.com

Direct: 541.261.6545

Fax:  541.512.0343

Visit our Web site at solarprofessional.com

On 3/9/09 5:25 PM, "Allan Sindelar"
<allan at positiveenergysolar.com> wrote:

Wayne,

Use this as a tool: http://www.solarabcs.org/utilitydisconnect/

and this: http://www.nrel.gov/docs/fy08osti/42675.pdf

Allan Sindelar 

allan(at)positiveenergysolar.com <mailto:allan at positiveenergysolar.com>

NABCEP Certified Solar PV Installer 

Positive
Energy, Inc.

3201 Calle Marie 

Santa Fe NM 87507 

505 424-1112 

www.positiveenergysolar.com 

Please consider the environment
before printing this e-mail. 

-----Original
Message-----

From:
re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org]
On Behalf Of Wayne Irwin

Sent: Monday, March 09, 2009 4:41 PM

To: re-wrenches at lists.re-wrenches.org

Subject: [RE-wrenches] Line Side Feed In and Disconnects

Hello
Wrenches,

Here in Gainesville, Fla. we have recently adopted a Feed In Tariff. 

So, now we are supposed to directly feed the line side of the utility meter
(essentially a new service). No big deal. 

As usual we use an AC disco between the inverter and the grid. However, the
permit department is requiring that we install and additional disco between the
existing service feed and the distribution panel to group all disco's in the
same location. This especially adds an additional expense when dealing with 3
phase systems as well as the raises the question, is this really the National
Electrical Code or just an interpretation? Your thoughts?

Wayne Irwin, President

Pure Energy Solar International Inc. 

Lic # CVC56695 

 <mailto:PureEnergySolar at hotmail.com>

Date:
Mon, 9 Mar 2009 18:20:57 -0400

From: reellison at gmail.com

To: re-wrenches at lists.re-wrenches.org

Subject: Re: [RE-wrenches] Small Torque Wrench

I got mine from "the knife and tool store" http://myworld.ebay.com/don19470/
on E bay. nice tool, adjustable 10 - 50 In Oz and he has others, just get the
adapter that lets you use 1/4" drive bits and your good to go. It is a
german tool and i use it on all breaker connections as well as others.

Later,

Bob

On Mon, Mar 9, 2009 at 12:10 PM, Peter Parrish
<peter.parrish at calsolareng.com> wrote:

We have a great torque wrench for  snugging down module clamps,
Sharp SRS bolts, etc. What do folks use to insure  that wire terminals are
torqued to spec? We’re talking 1.1 to 3.3 N-m (10-30  in-lbs).
I’m imagining something compact like an over-sized screwdriver.  

- Peter

Peter T. Parrish,  President

California Solar Engineering, Inc.

820 Cynthia Ave., Los  Angeles, CA 90065

Ph 323-258-8883, Mobile 323-839-6108, Fax  323-258-8885

CA Lic. 854779, NABCEP Cert. 031806-26

peter.parrish at calsolareng.com  

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