date:20100722

Re: [RE-wrenches] #10 THWN-2

2010-07-22 Thread Phil Undercuffler

Marco,

I found the same situation as what David mentions -- when we were doing a
high profile job that was going to be inspected by a certain someone from
Las Cruces, all the wire available from local suppliers was only physically
marked as THHN / THWN, but when we dug a little deeper and found the actual
spec sheets from the manufacturer we were able to determine that the wire
actually was rated as THWN-2 (plus a whole alphabet soup worth of additional
listings), although it wasn't marked as such.  Have the vendor pull up the
spec sheet on the wire brands they typically carry, and keep a couple copies
in your "for the inspector" file.

Phil Undercuffler



On Thu, Jul 22, 2010 at 7:33 PM, David Brearley <
david.brear...@solarprofessional.com> wrote:

>  Marco,
>
> The #10 THWN wire that your local suppliers carry may be cross-listed as
> THWN-2. My understanding is that it is not uncommon for smaller gauge wire
> to carry more listings than are printed on its insulation. (If that’s not
> true, we’ll find out shortly from someone on the list.) If your local
> supplier can’t confirm this cross-listing for you, I’d try tracing back to
> ask their supplier or the manufacturer.
>
> David Brearley, Senior Technical Editor
> *SolarPro* magazine
>
> On 7/23/10 12:52 AM, "Marco Mangelsdorf"  wrote:
>
> Finding that wire in these here parts is pretty much impossible.
>
> Can any of my CA. brethren/sistren provide me any leads on wholesalers in
> either northern or southern CA. that carry #10 THWN-2 wire?
>
> Thanks,
> marco
>
>
> --
>
>
>
>
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Re: [RE-wrenches] Encore Wire #10 THWN-2

2010-07-22 Thread Louis Woofenden



Hi Marco,

I'd second Dave's recommendation regarding Encore Wire.

We've been using #10 and #12 THWN-2 made by Encore for a few months. 
When I called Encore, they were helpful finding an electrical supply 
house that carries it here in Tucson. The wire is indeed rated 
THHN/THWN/THWN-2, so it seems like I have to explain and confirm the 
dual rating to the salespeople just about every time I order it. But 
it's available, and pretty cost effective.


Cheers,

Louis Woofenden
Net Zero Solar
Tucson, AZ

On 7/22/10 7:44 PM, Dave Click wrote:
THWN-2 smaller than #8 is hard to find but I hear 
http://www.encorewire.com/site_flash/index.html makes it and that 
Graybar sells it. When I asked Southwire about it about two years ago, 
I got a collective "huh?"


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Re: [RE-wrenches] #10 THWN-2

2010-07-22 Thread Dave Click

THWN-2 smaller than #8 is hard to find but I hear 
http://www.encorewire.com/site_flash/index.html makes it and that 
Graybar sells it. When I asked Southwire about it about two years ago, I 
got a collective "huh?"

 Original Message 
Subject: Re: [RE-wrenches] #10 THWN-2
From: David Brearley 
To: RE-wrenches 
Date: 2010/7/22 21:33

Marco,

The #10 THWN wire that your local suppliers carry may be cross-listed as
THWN-2. My understanding is that it is not uncommon for smaller gauge
wire to carry more listings than are printed on its insulation. (If
that’s not true, we’ll find out shortly from someone on the list.) If
your local supplier can’t confirm this cross-listing for you, I’d try
tracing back to ask their supplier or the manufacturer.

David Brearley, Senior Technical Editor
/SolarPro/ magazine

On 7/23/10 12:52 AM, "Marco Mangelsdorf"  wrote:

Finding that wire in these here parts is pretty much impossible.

Can any of my CA. brethren/sistren provide me any leads on
wholesalers in either northern or southern CA. that carry #10 THWN-2
wire?

Thanks,
marco

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Re: [RE-wrenches] #10 THWN-2

2010-07-22 Thread David Brearley

Marco,

The #10 THWN wire that your local suppliers carry may be cross-listed as
THWN-2. My understanding is that it is not uncommon for smaller gauge wire
to carry more listings than are printed on its insulation. (If that¹s not
true, we¹ll find out shortly from someone on the list.) If your local
supplier can¹t confirm this cross-listing for you, I¹d try tracing back to
ask their supplier or the manufacturer.

David Brearley, Senior Technical Editor
SolarPro magazine 

On 7/23/10 12:52 AM, "Marco Mangelsdorf"  wrote:

> Finding that wire in these here parts is pretty much impossible.
>  
> Can any of my CA. brethren/sistren provide me any leads on wholesalers in
> either northern or southern CA. that carry #10 THWN-2 wire?
>  
> Thanks,
> marco
>  
> 
> 

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Re: [RE-wrenches] RETURN AMP SETTING

2010-07-22 Thread Darryl Thayer

I am talking with a customer who wants to do a standalone system using an 
Endurance wind machine, solar, and genset.   I have no experience with 
Endurance other than to know it is a good machine.  Talking with Magnum today 
they informed me that the MS 4XXX PAE inverter, combined with the ARC remote 
control, and BMK battery monitoring kit can do enhanced SOC control.  Has 
anyone compared this with the Outback as I have not used the PAE inverter yet, 
only the AE inverter?  
Darryl

--- On Wed, 7/21/10, Darryl Thayer  wrote:

From: Darryl Thayer 
Subject: Re: [RE-wrenches] RETURN AMP SETTING
To: "RE-wrenches" 
Date: Wednesday, July 21, 2010, 9:35 PM

That is a good question, I have not an answer, but of course it should be based 
on the amp hour of the battery bank, absorb charging voltage, and of course the 
charging source in the case of generators.  Following Ron's advise start at C/5 
for SOC less than 50% then C/10 till about 70% SOC and then C/15 till 80% then 
C/20 to 90 %. the problem we have no way to set these values, Perhaps Ron could 
give is a routine?  The closet to SOC charging is the Outback and then the 
Magnum but both miss the goal.  

--- On Wed, 7/21/10, Dana  wrote:

From: Dana 
Subject: [RE-wrenches] RETURN AMP SETTING
To: "'RE-wrenches'" 
Date:
 Wednesday, July 21, 2010, 5:54 PM




 
 







As the % of full charge is related to the of degree absorption
& gravity [the denser & more charged acid descending, and lighter acid rising]
@ what point in the absorption would be prudent to stop charging? 

   

I used to cut off the charge on the Trace SW series at 12 “return
amps”, VS. the factory default I think was at 5 amps.  This has &
continues to work well but I never had anyone really answer this function
clearly. 

   

Is there a battery manufacturer  or wrench that would
care to comment on the:   

The minimum “Return” amps to disconnect for a “full”
charge? 

OR 

The time required per 100 AHR after reaching the Absorption
point setting for the mix to occur? 

   

I realize that battery construction, battery condition, age
and temperature and the current power usage will also play into this factor and
it may not be a simple answer. 

   

   

   

   

   



 Dana Orzel 

   

Great Solar Works, Inc 

E - d...@solarwork.com 

V - 970.626.5253 

F - 970.626.4140 

C - 970.209.4076 

web - www.solarwork.com 

Responsible Technologies for Responsible People since
1988" 



   





From:
re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark
Frye

Sent: Wednesday, July 21, 2010 4:25 PM

To: al...@positiveenergysolar.com; 'RE-wrenches'

Subject: Re: [RE-wrenches] Propane Generator, Dual Outback Inverters 





   

Allen, 

  

Can I infer that if you are
shutting off the gen before charge rates drop in absorption that you are
running only briefly in the absorb phase? Or do your charge currents remain
high through out an extended absortion phase? 

  

Perhaps you have plenty of PV
which you rely upon to bring the batteries up through the absorption phase,
once the gen is shut off. 

  

I would be interest to learn more
about your approach to this. 

  

Thanks, 

 

Mark Frye


Berkeley Solar
Electric Systems 

303 Redbud Way


Nevada
City,  CA 95959 

(530) 401-8024


www.berkeleysolar.com   



  



   







From:
re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan
Sindelar

Sent: Wednesday, July 21, 2010 3:17 PM

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

Subject: Re: [RE-wrenches] Propane Generator, Dual Outback Inverters 

The Onan RS2 shown in the generators article in HP
131 page 98 has performed flawlessly as backup support to an Outback quad-stack
of VFX3648s. Differences, however, are that this 20kW gennie charges four
inverters, rather than two; the elevation is 6,600 feet for about a 20% output
deration; there are no huge loads above charging draw; and the client is aware
enough to shut it off before absorption reduces the charge rate - all different
conditions than you have described, as the gennie is usually fully loaded and
running in balance.



Darryl is right about the amount of words necessary. 



Allan
Sindelar

al...@positiveenergysolar.com

NABCEP Certified Photovoltaic Installer

EE98J Journeyman Electrician

Positive Energy, Inc.

3201 Calle Marie

Santa Fe, New Mexico 87507

505 424-1112

www.positiveenergysolar.com 



No virus found in this incoming message.

Checked by AVG - www.avg.com

Version: 9.0.851 / Virus Database: 271.1.1/3008 - Release Date: 07/21/10
00:36:00 



 


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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Kent Osterberg





Dana,

2.6% voltage drop also means 2.6% power loss.  To go from 2.6% loss to
1.6% loss you gain about 4.1 watts for the extra $22.  That is
$5.36/watt so it probably makes sense to use the larger wire.  Now
compare 1.6% and 0.4%: you gain about 4.9 watts for the extra $140,
that's $28.57/watt.  If you can buy and install PV for much less than
that, how can you justify such little gain from the extra wire cost?  2
or 3 AWG may be worth it, but it sure doesn't look like 1 AWG is a
smart choice.

Kent Osterberg
Blue Mountain Solar


Dana wrote:

  
  
  

  
  Ray,
  
   
  The
$ could be making power I agree on a large scale project. 
   
  The
point here is where is the cutoff point?
   
  Let’s
take a very small cabin system:
  410
watts or 13 amps  [inc.1.25%]@ 44VOC, over a 90’ one-way run.
  Utilizing
 and Electro-calc with 2008 NEC installed
   
  2.6%VD
– 1.1vd requires a pair #6 Thhn @ $0.66/ft = $118 for 180’wire @ whole
sale
price.
   
  1.6%VD
– 0.7vd requires a pair #4 Thhn @ $0.78/ft = $140 for 180’wire @ whole
sale.
   
  0.4%VD
– 0.4vd requires a pair #1 Thhn @ $1.55/ft = $279for 180’ wire @ whole
sale.
   
  I
grant you the cost savings up front, and MPPT covers a lot errors these
days,
but where do we say what is better?
   
  So
my question is-
  In
MPPT what is .3volt drop worth VS 0.7vd VS 1.1vd worth in MPPT charge
capabilities over the life of the system? 
  Weather
it is a utility scale project or a small cabin.
   
   
  
  Thanks, 
Dana Orzel
   
  Great
Solar Works, Inc
  E -
d...@solarwork.com
  V -
970.626.5253
  F -
970.626.4140
  C -
970.209.4076
  web
- www.solarwork.com
   
  "Responsible
Technologies for Responsible People since 1988"
  
   
  
  
  From:
re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R
Ray
Walters
  Sent: Thursday, July 22, 2010 3:30 PM
  To: RE-wrenches
  Subject: Re: [RE-wrenches] calculating DC voltage drop
  
  
   
  Hi Dana;
  
   
  
  
  I'd say that's a bit
overkill for
today's market. That money could be making more power, not just
preventing
losses. 
  
  
  Definitely a law of
diminishing
returns on wire sizing. 
  
  
  If you allocated 50%
of the budget
to wire, and 50% to PV, your losses would be very low, (immeasurable
but
unfortunately still there) but your total system production vs. the
money spent
would be terrible.
  
  
  I'm only using this
ridiculous
example to show, that at some point, we all spend money on more PV, not
bigger
wire. 
  
  
  I pick that point
based on sound
economic analysis, not some over applied rule of thumb. As copper costs
rise,
and PV gets cheaper, that point moves up. 
  
  
  If copper was still
at 20th century
prices, and PV were $10/ watt, your 1% might very well be the right
answer.
  
  
   
  
  
  ( this is also the
point where
Bob-O starts hammering me, so I'd better run. ??)
  
  
   
  
  
  
  
  
  R.
Walters
  
  
  r...@solarray.com
  
  
  Solar
Engineer
  
  
   
  
  
   
  
  
  
  
  
  
  
  
  
  
  

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Re: [RE-wrenches] aluminum heat fins for radiant retrofit...who's got 'em?

2010-07-22 Thread Darryl Thayer

I have used this approach with 1/2 inch nom. copper tube, it works.  The 
Aluminum I got form New Jersey Aluminum, they sold out to another company.  I 
am not sure it is made any more, but I had a custom extrusion made for me for 
about $3000  I have also seen a thin folded AL fin from floor heat people.  
Study your floor heating manuals well for sizing.   

--- On Thu, 7/22/10, Mick Abraham  wrote:

From: Mick Abraham 
Subject: [RE-wrenches] aluminum heat fins for radiant retrofit...who's got 'em?
To: "RE-wrenches" 
Date: Thursday, July 22, 2010, 8:56 AM

Hello, Wrenches~
Please see the photo on page 48 of the latest Home Power magazine (#138). This 
shows aluminum fins with an extruded clip into which Rehau type radiant floor 
tubing can be clipped. 

Where can I get these parts for resale?
Have any of you observed an installation where this approach actually worked 
OK? I'm sure the aluminum  fin would extract heat from the tubing OK but the 
wood subfloor won't extract heat from the aluminum very quickly. Insulation 
between the aluminum fin and the air below it might help, right?

My client wants to retrofit solar heat to an existing home which does not have 
the in-floor radiant tubing embedded in lightweight concrete--the more common 
way to do a radiant floor. He had planned to drive existing baseboard radiators 
but the higher temperature which those require (compared to a radiant floor) 
led to this pursuit.

Thanks in advance,
Mick Abraham, Proprietor
www.abrahamsolar.com

Voice: 970-731-4675

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[RE-wrenches] #10 THWN-2

2010-07-22 Thread Marco Mangelsdorf

Finding that wire in these here parts is pretty much impossible.

 

Can any of my CA. brethren/sistren provide me any leads on wholesalers in
either northern or southern CA. that carry #10 THWN-2 wire?

 

Thanks,

marco

 

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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Bill Brooks

All,

 

This is all very interesting, but on the dc side, it is primarily an issue
of energy loss for large grid-connected systems. My rule is 2% voltage drop
for dc side and 1% for ac side.

 

When we talk about dc  % voltage drop, most of what has been discussed in
this thread is instantaneous voltage drop. That is interesting, but
year-round voltage losses are more important. There are two ways to get
this:

 

1.   Use a simulation program like PVSyst to calculate the voltage drop
every hour of the day and give you an overall loss for the year.

2.   Take 80% of Imp for the array and use that current with the nominal
voltage of the array (330 Volts for a 600V array). The reason for 80% of Imp
is that half of the energy is delivered above this number and half below. It
makes an ideal "nominal" current of the array.

 

By using one of these methods, you will calculate the accurate energy loss
on the dc side.

 

Bill.

 

From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan
Sindelar
Sent: Thursday, July 22, 2010 3:12 PM
To: m...@solren.com; RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage drop

 

Mike,
I would respectfully challenge both reasons ;^)} . The responses already
posted today cover them: you don't need to compensate for intermittent
high-insolation conditions when sizing for voltage loss, as this is not a
Code issue; Code addresses ampacity and OCP issues. And being conservative
means you add unnecessarily to wire cost (sometimes substantially at 25%
greater current) when that money could be better spent on more PV, with an
ultimately greater annualized return of total energy per $$ spent. Ray
Walters' recent posts cover this well.

Allan Sindelar
  al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com  


On 7/22/2010 3:53 PM, Michael Kelly wrote: 

Allan,

 

I use Imp*1.25 because NEC calls out a 125% adder for unexpected
high-insolation conditions (snowscapes, cloud effect, yellow houses next
door, etc).  And because I am an engineer and like to be conservative :).

 

-Mike

---

Michael Kelly
Applications Engineer

NABCEP Certified Solar PV Installer T

toplogo
Solectria Renewables, LLC

360 Merrimack St.

Building 9, Floor 2

Lawrence, MA 01843
Phone: 978-683-9700 ext. 167
Fax: 978-683-9702

m...@solren.com

www.solren.com  

 

From: Allan Sindelar [mailto:al...@positiveenergysolar.com] 
Sent: Thursday, July 22, 2010 5:26 PM
To: m...@solren.com; RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage drop

 

Mike,
Why do you make this exception, please?

Allan Sindelar
  al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com  

 
 
 
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[RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Dana

Ray, 

 

The $ could be making power I agree on a large scale project. 

 

The point here is where is the cutoff point?

 

Let’s take a very small cabin system:

410 watts or 13 amps  [inc.1.25%]@ 44VOC, over a 90’ one-way run.

Utilizing  and Electro-calc with 2008 NEC installed

 

2.6%VD – 1.1vd requires a pair #6 Thhn @ $0.66/ft = $118 for 180’wire @ whole 
sale price.

 

1.6%VD – 0.7vd requires a pair #4 Thhn @ $0.78/ft = $140 for 180’wire @ whole 
sale.

 

0.4%VD – 0.4vd requires a pair #1 Thhn @ $1.55/ft = $279for 180’ wire @ whole 
sale.

 

I grant you the cost savings up front, and MPPT covers a lot errors these days, 
but where do we say what is better?

 

So my question is-

In MPPT what is .3volt drop worth VS 0.7vd VS 1.1vd worth in MPPT charge 
capabilities over the life of the system? 

Weather it is a utility scale project or a small cabin.

 

 

Thanks,  Dana Orzel

 

Great Solar Works, Inc

E - d...@solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

 

"Responsible Technologies for Responsible People since 1988"

 

From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters
Sent: Thursday, July 22, 2010 3:30 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage drop

 

Hi Dana;

 

I'd say that's a bit overkill for today's market. That money could be making 
more power, not just preventing losses. 

Definitely a law of diminishing returns on wire sizing. 

If you allocated 50% of the budget to wire, and 50% to PV, your losses would be 
very low, (immeasurable but unfortunately still there) but your total system 
production vs. the money spent would be terrible.

I'm only using this ridiculous example to show, that at some point, we all 
spend money on more PV, not bigger wire. 

I pick that point based on sound economic analysis, not some over applied rule 
of thumb. As copper costs rise, and PV gets cheaper, that point moves up. 

If copper was still at 20th century prices, and PV were $10/ watt, your 1% 
might very well be the right answer.

 

( this is also the point where Bob-O starts hammering me, so I'd better run. ??)

 

R. Walters

r...@solarray.com

Solar Engineer

 

 





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Re: [RE-wrenches] RETURN AMP SETTING

2010-07-22 Thread Michael Welch

Hi gang. Just a quick note. It has awhile since Christopher was with Outback. 
Steve Higgins is the Outback manufacturer representative on the list.

Dana wrote at 08:36 AM 7/22/2010:
 
>Chris Freitas of Outback can you chime in here?
> 
>Thanks,Â  Dana Orzel

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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Allan Sindelar



  
  
Mike,
I would respectfully challenge both reasons ;^)} . The responses
already posted today cover them: you don't need to compensate for
intermittent high-insolation conditions when sizing for voltage
loss, as this is not a Code issue; Code addresses ampacity and OCP
issues. And being conservative means you add unnecessarily to wire
cost (sometimes substantially at 25% greater current) when that
money could be better spent on more PV, with an ultimately greater
annualized return of total energy per $$ spent. Ray Walters' recent
posts cover this well.


  
  
  
  
  
  
  
  
Allan Sindelar
Allan@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com
  


On 7/22/2010 3:53 PM, Michael Kelly wrote:

  
  
  
  
  
Allan,
 
I use Imp*1.25 because NEC calls out a 125%
adder for
unexpected high-insolation conditions (snowscapes, cloud
effect, yellow houses
next door, etc).  And because I am an engineer and like to
be conservative
:).
 
-Mike

  ---
  Michael Kelly
  Applications Engineer
  NABCEP Certified Solar PV Installer ™
  
  Solectria Renewables, LLC
  360 Merrimack St.
  Building 9, Floor 2
  Lawrence, MA 01843
  Phone: 978-683-9700 ext. 167
  Fax: 978-683-9702
  m...@solren.com
  www.solren.com

 

  
From: Allan Sindelar
[mailto:al...@positiveenergysolar.com] 
Sent: Thursday, July 22, 2010 5:26 PM
To: m...@solren.com; RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage
drop
  

 
Mike,
  Why do you make this exception, please?

  Allan
  Sindelar
  Allan@positiveenergysolar.com
  NABCEP Certified Photovoltaic Installer
  EE98J Journeyman Electrician
  Positive Energy, Inc.
  3201 Calle Marie
  Santa Fe, New Mexico 87507
  505 424-1112
  www.positiveenergysolar.com

 
  
  

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Re: [RE-wrenches] Imbalance In Multiple String Charging Current

2010-07-22 Thread Exeltech

Mark,

If you had one "healthy" string connected in parallel with two "weak" strings, 
the tendency would be for the weaker strings to pull the stronger string down 
to their level.  It's more likely an impedance issue in the string with the 
lower current.  All other things being equal, look for bad connections in the 
low-current string.  "Bad" in this case could be due to corrosion, one or more 
poor crimps, one or more bad cells, and so forth.

Your best friend here is your DVM.  Apply a charge current to the entire 
battery and look for a point in the low-I string with a higher-than-normal 
voltage drop, especially when compared with the other two strings.  It could 
also be a cumulative loss, such as several "sort of ok" connections, but each 
of which may have [say] a few fractions of a volt more drop across them than 
their counterparts in the other strings.

It takes only a few millivolts difference to reduce the current through a 
battery to something much less than would otherwise be flowing.


Dan


--- On Thu, 7/22/10, Mark Frye  wrote:

From: Mark Frye 
Subject: Re: [RE-wrenches] Imbalance In Multiple String Charging Current
To: "'RE-wrenches'" 
Date: Thursday, July 22, 2010, 4:16 PM

Imbalance In Multiple String Charging Current

 
 
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OK,
 
So no takers for the low current string being in a 
healthier, higher state of charge!
 
Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 

(530) 401-8024 

www.berkeleysolar.com 




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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Michael Kelly

Allan,

 

I use Imp*1.25 because NEC calls out a 125% adder for unexpected
high-insolation conditions (snowscapes, cloud effect, yellow houses next
door, etc).  And because I am an engineer and like to be conservative :).

 

-Mike

---

Michael Kelly
Applications Engineer

NABCEP Certified Solar PV Installer T

toplogo
Solectria Renewables, LLC

360 Merrimack St.

Building 9, Floor 2

Lawrence, MA 01843
Phone: 978-683-9700 ext. 167
Fax: 978-683-9702

m...@solren.com

www.solren.com  

 

From: Allan Sindelar [mailto:al...@positiveenergysolar.com] 
Sent: Thursday, July 22, 2010 5:26 PM
To: m...@solren.com; RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage drop

 

Mike,
Why do you make this exception, please?

Allan Sindelar
  al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com  

 
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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread R Ray Walters

Hi Dana;

I'd say that's a bit overkill for today's market. That money could be making 
more power, not just preventing losses. 
Definitely a law of diminishing returns on wire sizing. 
If you allocated 50% of the budget to wire, and 50% to PV, your losses would be 
very low, (immeasurable but unfortunately still there) but your total system 
production vs. the money spent would be terrible.
I'm only using this ridiculous example to show, that at some point, we all 
spend money on more PV, not bigger wire. 
I pick that point based on sound economic analysis, not some over applied rule 
of thumb. As copper costs rise, and PV gets cheaper, that point moves up. 
If copper was still at 20th century prices, and PV were $10/ watt, your 1% 
might very well be the right answer.

( this is also the point where Bob-O starts hammering me, so I'd better run. ☹☺)

R. Walters
r...@solarray.com
Solar Engineer




On Jul 22, 2010, at 2:58 PM, Dana wrote:

> For array to power center or Inverter; I use 125% of amps @ max power and run 
> the wire calculations at 1% VD.
>  
> We have set Fluke meters on clamped on @ both ends and talked with radios & 
> compared the readings. We have not seen any noticeable VD down to .00vdc.
>  
> Perhaps overkill?
>  
> Thanks,  Dana Orzel
>  
> Great Solar Works, Inc
> E - d...@solarwork.com
> V - 970.626.5253
> F - 970.626.4140
> C - 970.209.4076
> web - www.solarwork.com
>  
> "Responsible Technologies for Responsible People since 1988"
>  
> From: re-wrenches-boun...@lists.re-wrenches.org 
> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Michael Kelly
> Sent: Thursday, July 22, 2010 2:13 PM
> To: 'RE-wrenches'
> Subject: Re: [RE-wrenches] calculating DC voltage drop
>  
> Hi All,
>  
> I agree with Ray with the exception that I use Imp*1.25 in my calculations.  
> I developed a simple spreadsheet for either fixed conductor size or for fixed 
> voltage drop.  You can feel free to use it by downloading here: 
> http://www.mechanicalmike.com/solar/DC_Voltage_Drop_Calculations_Template_04_20_2010.xltx.
>  
> - Mike
> ---
> Michael Kelly
> Applications Engineer
> NABCEP Certified Solar PV Installer ™
> 
> Solectria Renewables, LLC
> 360 Merrimack St.
> Building 9, Floor 2
> Lawrence, MA 01843
> Phone: 978-683-9700 ext. 167
> Fax: 978-683-9702
> m...@solren.com
> www.solren.com
>  
> From: re-wrenches-boun...@lists.re-wrenches.org 
> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters
> Sent: Thursday, July 22, 2010 3:45 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] calculating DC voltage drop
>  
> I use actual operating current, without multipliers. I also use actual 
> temperatures, not the worst case temperatures that many use.
> I created a spread sheet that uses the NEC adjustments for wire temperature, 
> (see NEC chapter 9, table 8, FPN 2)
> It makes quite a difference!
> Volt drop and the accompanying loss of energy production needs to be looked 
> at realistically under normal operating conditions. Adding worst case 
> multipliers is necessary for sizing cables and breakers for safety, but it 
> isn't appropriate when calculating energy losses. We shouldn't do an energy 
> loss analysis for a situation that might never occur, or for only a very 
> small % of the time. 
> A correct analysis will reflect actual losses over the lifetime of the 
> system, so that an informed economic decision can be made. Especially on 
> larger systems with long runs, its worth it to you and the client to use real 
> world numbers, not blind over sizing.
> I got into this over a decade ago, when I noticed that actual measured volt 
> drop was much less than calculated, now my calculations match real 
> measurements. 
>  
> R. Walters
> r...@solarray.com
> Solar Engineer
>  
>  
>  
> 
>  
> On Jul 22, 2010, at 1:22 PM, Marco Mangelsdorf wrote:
>  
> 
> When calculating the voltage drop from a PV array to the inverter, what’s the 
> most common accepted practice?  To use the Isc X 1.25 or 1.56 as the 
> multiplier?
>  
> Thanks,
> marco
>  
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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Allan Sindelar



  
  
Mike,
Why do you make this exception, please?


  
  
  
  
  
  
  
  
Allan Sindelar
Allan@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com
  


On 7/22/2010 2:12 PM, Michael Kelly wrote:

  
  
  
  
  
Hi
All,
 
I
agree with Ray with the exception that I use Imp*1.25 in my
calculations. 
I developed a simple spreadsheet for either fixed conductor
size or for fixed
voltage drop.  You can feel free to use it by downloading
here: http://www.mechanicalmike.com/solar/DC_Voltage_Drop_Calculations_Template_04_20_2010.xltx.
 
-
Mike

  ---
  Michael
  Kelly
  Applications Engineer
  NABCEP
Certified
  Solar PV Installer ™
  
  Solectria Renewables, LLC
  360
Merrimack
  St.
  Building
9,
  Floor 2
  Lawrence,
MA
  01843
  Phone: 978-683-9700 ext. 167
  Fax: 978-683-9702
  m...@solren.com
  www.solren.com

 

  
From:
re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On
  Behalf Of R Ray
Walters
Sent: Thursday, July 22, 2010 3:45 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage
drop
  

 
I use actual operating current, without
  multipliers. I also
  use actual temperatures, not the worst case temperatures that
  many use.

  I created a spread sheet that uses the
NEC adjustments for
wire temperature, (see NEC chapter 9, table 8, FPN 2)


  It makes quite a difference!
  
Volt drop and the accompanying loss of
  energy production
  needs to be looked at realistically under normal operating
  conditions. Adding
  worst case multipliers is necessary for sizing cables and
  breakers for safety,
  but it isn't appropriate when calculating energy losses.
  We shouldn't do an
  energy loss analysis for a situation that might never
  occur, or for only a very
  small % of the time. 
  
  
A correct analysis will reflect actual
  losses over the
  lifetime of the system, so that an informed economic
  decision can be made.
  Especially on larger systems with long runs, its worth it
  to you and the client
  to use real world numbers, not blind over sizing.
  
  
I got into this over a decade ago, when
  I noticed that
  actual measured volt drop was much less than calculated,
  now my calculations
  match real measurements. 
  
  
 

  
R. Walters
  
  
r...@solarray.com
  
  
Solar Engineer
  
  
 
  
  
 
  
  
  


 

  
On Jul 22, 2010, at 1:22 PM, Marco
  Mangelsdorf wrote:
  
  


  

  When
  calculating the voltage drop from a PV array to
  the inverter, what’s the
  most common accepted practice?  To use the Isc X
  1.25 or 1.56 as the
  multiplier?


   


  Thanks,


  marco


   

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Re: [RE-wrenches] Imbalance In Multiple String Charging Current

2010-07-22 Thread Mark Frye

OK,
 
So no takers for the low current string being in a healthier, higher state
of charge!
 
Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 
(530) 401-8024 
  www.berkeleysolar.com 
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Re: [RE-wrenches] line-side tap in subpanel

2010-07-22 Thread R Ray Walters

It would depend on which side of the OCD the 380 amp rated cable was on. IF the 
400 A OCD is integral to the panel, then it doesn't matter what the cable size 
is on the other side of the OCD, it's protected by the OCD, and the current 
can't exceed that. If the OCD is remote and the subpanel doesn't have a main 
OCD, then technically you'd have to do the calculations at 380 amps.
In most cases, though, the cable would never see additional current, unless a 
2nd subpanel were being fed by it.
Basically look at the circuit, and see if there is any point that could be fed 
by more current than the OCD rating. If so, apply the 120% rule for that entire 
section ( buss bar & conductors). Most points in the circuit though, will 
actually see a reduction in current, thanks to the PV backfeed. 
Funny we get penalized for adding PV, but don't get any code benefits from 
reducing current at other points.

R. Walters
r...@solarray.com
Solar Engineer

On Jul 22, 2010, at 2:49 PM, Erika M. Weliczko wrote:

> Greetings all,
> When the subpanel is fed with 380A wire and the OCD is 400A and the panel bus 
> is 400A, which number would be used for determining 120% capacity?
> I’m thinking the 400A because the bus would be overfed before the wire?
> So if we want to land 225A of OCD for solar output on the line terminals or a 
> backfed breaker, we need to derate existing OCD to subpanel all the way to 
> 255A, or realisitically 250A if the load calcs allow it.
> Or replace the feeders serving the subpanel. Yeah, right.
>  
> While for this one it does not end up mattering, it raises the question.
>  
> Thanks for input,
> Erika
>  
>  
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[RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Dana

For array to power center or Inverter; I use 125% of amps @
max power and run the wire calculations at 1% VD.

 

We have set Fluke meters on clamped on @ both ends and
talked with radios & compared the readings. We have not seen
any noticeable VD down to .00vdc.

 

Perhaps overkill?

 

Thanks,  Dana Orzel

 

Great Solar Works, Inc

E - d...@solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

 

"Responsible Technologies for Responsible People since 1988"

 

From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf
Of Michael Kelly
Sent: Thursday, July 22, 2010 2:13 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] calculating DC voltage drop

 

Hi All,

 

I agree with Ray with the exception that I use Imp*1.25 in
my calculations.  I developed a simple spreadsheet for
either fixed conductor size or for fixed voltage drop.  You
can feel free to use it by downloading here:
http://www.mechanicalmike.com/solar/DC_Voltage_Drop_Calculat
ions_Template_04_20_2010.xltx.

 

- Mike

---

Michael Kelly
Applications Engineer

NABCEP Certified Solar PV Installer T

toplogo
Solectria Renewables, LLC

360 Merrimack St.

Building 9, Floor 2

Lawrence, MA 01843
Phone: 978-683-9700 ext. 167
Fax: 978-683-9702

m...@solren.com

www.solren.com  

 

From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf
Of R Ray Walters
Sent: Thursday, July 22, 2010 3:45 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage drop

 

I use actual operating current, without multipliers. I also
use actual temperatures, not the worst case temperatures
that many use.

I created a spread sheet that uses the NEC adjustments for
wire temperature, (see NEC chapter 9, table 8, FPN 2)

It makes quite a difference!

Volt drop and the accompanying loss of energy production
needs to be looked at realistically under normal operating
conditions. Adding worst case multipliers is necessary for
sizing cables and breakers for safety, but it isn't
appropriate when calculating energy losses. We shouldn't do
an energy loss analysis for a situation that might never
occur, or for only a very small % of the time. 

A correct analysis will reflect actual losses over the
lifetime of the system, so that an informed economic
decision can be made. Especially on larger systems with long
runs, its worth it to you and the client to use real world
numbers, not blind over sizing.

I got into this over a decade ago, when I noticed that
actual measured volt drop was much less than calculated, now
my calculations match real measurements. 

 

R. Walters

r...@solarray.com

Solar Engineer

 

 

 

 

On Jul 22, 2010, at 1:22 PM, Marco Mangelsdorf wrote:

 

When calculating the voltage drop from a PV array to the
inverter, what's the most common accepted practice?  To use
the Isc X 1.25 or 1.56 as the multiplier?

 

Thanks,

marco

 

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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread R Ray Walters

Marco and I were just discussing this as well. For long term energy loss 
purposes, you really would want to use annual average voltage and current for 
the array. (let's see that on a module spec sheet ☺) 
Basically, it would really depend on the installation and location. I could see 
for a hot roof in a hot climate that voltage on avg. would be lower than MPP, 
and current would be higher, although, I think 25% higher on avg. would be 
unlikely.
Also we discussed wire temperature, and not only would it need to be annual 
averaged, it would also be averaged for the entire run, (ie. 20 ft are air 
conditioned, and 20 ft are in direct sun, you would average the 2 temps 
expected).
The whole idea here is to get the calculations as close as possible to the 
actual losses, so that you will know accurately how many kWh your wire choice 
will cost over the next 20 years.
The true test of your calculations will be confirmed with actual voltage drops 
measured on the proverbial "average" day.

R. Walters
r...@solarray.com
Solar Engineer




On Jul 22, 2010, at 2:12 PM, Michael Kelly wrote:

> Hi All,
>  
> I agree with Ray with the exception that I use Imp*1.25 in my calculations.  
> I developed a simple spreadsheet for either fixed conductor size or for fixed 
> voltage drop.  You can feel free to use it by downloading here: 
> http://www.mechanicalmike.com/solar/DC_Voltage_Drop_Calculations_Template_04_20_2010.xltx.
>  
> - Mike
> ---
> Michael Kelly
> Applications Engineer
> NABCEP Certified Solar PV Installer ™
> 
> Solectria Renewables, LLC
> 360 Merrimack St.
> Building 9, Floor 2
> Lawrence, MA 01843
> Phone: 978-683-9700 ext. 167
> Fax: 978-683-9702
> m...@solren.com
> www.solren.com
>  
> From: re-wrenches-boun...@lists.re-wrenches.org 
> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters
> Sent: Thursday, July 22, 2010 3:45 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] calculating DC voltage drop
>  
> I use actual operating current, without multipliers. I also use actual 
> temperatures, not the worst case temperatures that many use.
> I created a spread sheet that uses the NEC adjustments for wire temperature, 
> (see NEC chapter 9, table 8, FPN 2)
> It makes quite a difference!
> Volt drop and the accompanying loss of energy production needs to be looked 
> at realistically under normal operating conditions. Adding worst case 
> multipliers is necessary for sizing cables and breakers for safety, but it 
> isn't appropriate when calculating energy losses. We shouldn't do an energy 
> loss analysis for a situation that might never occur, or for only a very 
> small % of the time. 
> A correct analysis will reflect actual losses over the lifetime of the 
> system, so that an informed economic decision can be made. Especially on 
> larger systems with long runs, its worth it to you and the client to use real 
> world numbers, not blind over sizing.
> I got into this over a decade ago, when I noticed that actual measured volt 
> drop was much less than calculated, now my calculations match real 
> measurements. 
>  
> R. Walters
> r...@solarray.com
> Solar Engineer
>  
>  
> 
> 
>  
> On Jul 22, 2010, at 1:22 PM, Marco Mangelsdorf wrote:
> 
> 
> When calculating the voltage drop from a PV array to the inverter, what’s the 
> most common accepted practice?  To use the Isc X 1.25 or 1.56 as the 
> multiplier?
>  
> Thanks,
> marco
>  
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[RE-wrenches] line-side tap in subpanel

2010-07-22 Thread Erika M. Weliczko

Greetings all,

When the subpanel is fed with 380A wire and the OCD is 400A and the panel
bus is 400A, which number would be used for determining 120% capacity?

I'm thinking the 400A because the bus would be overfed before the wire?

So if we want to land 225A of OCD for solar output on the line terminals or
a backfed breaker, we need to derate existing OCD to subpanel all the way to
255A, or realisitically 250A if the load calcs allow it.

Or replace the feeders serving the subpanel. Yeah, right.

 

While for this one it does not end up mattering, it raises the question.

 

Thanks for input,

Erika

 

 

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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Michael Kelly

Hi All,

 

I agree with Ray with the exception that I use Imp*1.25 in my calculations.
I developed a simple spreadsheet for either fixed conductor size or for
fixed voltage drop.  You can feel free to use it by downloading here:
http://www.mechanicalmike.com/solar/DC_Voltage_Drop_Calculations_Template_04
_20_2010.xltx.

 

- Mike

---

Michael Kelly
Applications Engineer

NABCEP Certified Solar PV Installer T

toplogo
Solectria Renewables, LLC

360 Merrimack St.

Building 9, Floor 2

Lawrence, MA 01843
Phone: 978-683-9700 ext. 167
Fax: 978-683-9702

m...@solren.com

www.solren.com  

 

From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray
Walters
Sent: Thursday, July 22, 2010 3:45 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] calculating DC voltage drop

 

I use actual operating current, without multipliers. I also use actual
temperatures, not the worst case temperatures that many use.

I created a spread sheet that uses the NEC adjustments for wire temperature,
(see NEC chapter 9, table 8, FPN 2)

It makes quite a difference!

Volt drop and the accompanying loss of energy production needs to be looked
at realistically under normal operating conditions. Adding worst case
multipliers is necessary for sizing cables and breakers for safety, but it
isn't appropriate when calculating energy losses. We shouldn't do an energy
loss analysis for a situation that might never occur, or for only a very
small % of the time. 

A correct analysis will reflect actual losses over the lifetime of the
system, so that an informed economic decision can be made. Especially on
larger systems with long runs, its worth it to you and the client to use
real world numbers, not blind over sizing.

I got into this over a decade ago, when I noticed that actual measured volt
drop was much less than calculated, now my calculations match real
measurements. 

 

R. Walters

r...@solarray.com

Solar Engineer

 

 





 

On Jul 22, 2010, at 1:22 PM, Marco Mangelsdorf wrote:





When calculating the voltage drop from a PV array to the inverter, what's
the most common accepted practice?  To use the Isc X 1.25 or 1.56 as the
multiplier?

 

Thanks,

marco

 

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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread R Ray Walters

I use actual operating current, without multipliers. I also use actual 
temperatures, not the worst case temperatures that many use.
I created a spread sheet that uses the NEC adjustments for wire temperature, 
(see NEC chapter 9, table 8, FPN 2)
It makes quite a difference!
Volt drop and the accompanying loss of energy production needs to be looked at 
realistically under normal operating conditions. Adding worst case multipliers 
is necessary for sizing cables and breakers for safety, but it isn't 
appropriate when calculating energy losses. We shouldn't do an energy loss 
analysis for a situation that might never occur, or for only a very small % of 
the time. 
A correct analysis will reflect actual losses over the lifetime of the system, 
so that an informed economic decision can be made. Especially on larger systems 
with long runs, its worth it to you and the client to use real world numbers, 
not blind over sizing.
I got into this over a decade ago, when I noticed that actual measured volt 
drop was much less than calculated, now my calculations match real 
measurements. 

R. Walters
r...@solarray.com
Solar Engineer

On Jul 22, 2010, at 1:22 PM, Marco Mangelsdorf wrote:

> When calculating the voltage drop from a PV array to the inverter, what’s the 
> most common accepted practice?  To use the Isc X 1.25 or 1.56 as the 
> multiplier?
>  
> Thanks,
> marco
>  
> ___
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[RE-wrenches] Fw: Preventing Worker Deaths in the Solar Energy Industry

2010-07-22 Thread Joel Davidson

- Original Message - 
From: face (CDPH-OHB) 
To: undisclosed-recipients: 
Sent: Thursday, July 22, 2010 10:36 AM
Subject: Preventing Worker Deaths in the Solar Energy Industry

California FACE Program Investigates the Deaths of 

Three Solar Installers

The California Fatality Assessment and Control Evaluation (FACE) program has 
recently investigated the deaths of three solar installers.  Two of the 
completed reports are now available online:

·Electrical worker dies when he falls through a skylight while 
installing solar panels on the roof of a warehouse (09CA003, PDF)

·Solar installer dies when he falls 35 feet from a scaffold after being 
electrocuted (08CA006, PDF)

The California FACE program published several fact sheets (available in both 
English and Spanish) based on these fatality investigations.  Fact sheets are 
written for workers, and can easily be incorporated into trainings and posted 
at the worksite: 

·Deadly Skylights! Solar Energy and Warehouse Workers Killed! (English 
PDF)  |  Spanish

·Solar Energy Technician Electrocuted! (English PDF)  |  Spanish

·Solar Panels: Lift Them Safely! (PDF)

We invite you to explore additional materials on our Web site:  
www.cdph.ca.gov/programs/ohb-face and e-mail f...@cdph.ca.gov for more 
information about this program funded by the National Institute for 
Occupational Safety and Health (NIOSH).

If you would like to receive e-mail notification of future California FACE 
work-related fatality investigation reports (including the third solar 
investigation), or would like to provide feedback to our program by evaluating 
any of our materials, please complete this short form:  
http://fs6.formsite.com/BuildSafe/face/ .

A complete archive of CA/FACE publications can be viewed at:

·http://www.cdph.ca.gov/programs/ohb-face/Pages/Publications.aspx 
(English) or 

·http://www.cdph.ca.gov/programs/ohb-face/Pages/SpanishPubs.aspx 
(Spanish).

Sincerely, 

Robert Harrison, MD, MPH Laura Styles, MPH

Principal Investigator Project 
Coordinator

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[RE-wrenches] Imbalance In Multiple String Charging Current

2010-07-22 Thread Dana

What do specific gravity and load, rest and charge VPC tests
say? 

 

The VPC tests will usually pinpoint a weak cell. 

Higher VPC reading under a high state of charge and lower
VPC under a big load, normally done with the array &
generator turned off to maximize the effect. 

 

Typically the specific gravity reading will confirm this VPC
test cell readings and the SG will be lower for that cell
too.

 

Thanks,  Dana Orzel

 

Great Solar Works, Inc

E - d...@solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

 

"Responsible Technologies for Responsible People since 1988"

 

From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf
Of Mark Frye
Sent: Thursday, July 22, 2010 11:30 AM
To: 'RE-wrenches'
Subject: [RE-wrenches] Imbalance In Multiple String Charging
Current

 

Folks, 

I have three strings of batteries cabled in parallel to a
common buss bar. 

During charging, one string takes significantly less current
than the others. 

What can I infer from this? Is the low current string
healthier, presenting higher impedance due to a higher state
of charge? Or is there a single bad cell with high impedance
in this string? Both, neither, something else, or can't know
without further information?

  
Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 
(530) 401-8024 
  www.berkeleysolar.com  

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.851 / Virus Database: 271.1.1/3021 - Release
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Re: [RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Matt Lafferty

Most appropriate is Ip-max. If you are "operating" @ ISC or above, your voltage 
has already dropped to zero... AKA 100% voltage drop.

Pray for Sun!

Matt Lafferty

-  Sent from my Palm Pre
On Jul 22, 2010 12:22 PM, Marco Mangelsdorf  wrote: 





When calculating the voltage drop from a PV array to the
inverter, what’s the most common accepted practice?  To use the Isc X
1.25 or 1.56 as the multiplier?

 

Thanks,

marco

 







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[RE-wrenches] calculating DC voltage drop

2010-07-22 Thread Marco Mangelsdorf

When calculating the voltage drop from a PV array to the inverter, what's
the most common accepted practice?  To use the Isc X 1.25 or 1.56 as the
multiplier?

 

Thanks,

marco

 

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Re: [RE-wrenches] Imbalance In Multiple String Charging Current

2010-07-22 Thread dan

try disconnecting all strings from each other... (check all electrolyte levels and Specific Gravity).. let them rest for a while... and compare individual battery voltages... you're looking for about 2 volt differences... (bad cells)... basically you're up against an ohm's law thing... higher Resistance (Impedance is an AC thing), less current I'd be looking for sulphation or a bad connection you may be able to eq each string individually, then recombine them... (Be sure to do your homework).. might be an aging battery thing... depending on, depending on, generally if they're over like 5 years old, their number may well be on the board. good luck. dbDan BrownFoxfire Energy Corp.Renewable Energy Systems(802)-483-2564www.Foxfire-Energy.comNABCEP #092907-44 Original Message Subject: [RE-wrenches] Imbalance In Multiple String Charging Current From: "Mark Frye" Date: Thu, July 22, 2010 1:30 pm To: "'RE-wrenches'" Folks, I have three strings of batteries cabled in parallel to a common buss bar. During charging, one string takes significantly less current than the others. What can I infer from this? Is the low current string healthier, presenting higher impedance due to a higher state of charge? Or is there a single bad cell with high impedance in this string? Both, neither, something else, or can't know without further information? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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Re: [RE-wrenches] Imbalance In Multiple String Charging Current

2010-07-22 Thread Kent Osterberg





Mark,

Do the interconnects total the same length in each string?  There could
be a bad connection somewhere in that string.  But more than likely
this behavior is the result of a cell (or cells) that has a high
impedance because it is sulfated.  How do the specific gravity numbers
look. 

Kent Osterberg
Blue Mountain Solar



Mark Frye wrote:

  
  
  Imbalance In Multiple String Charging Current

  Folks,
  
  I have three strings of batteries
cabled in parallel to a common buss bar.
  
  During charging, one string takes
significantly less current than the others.
  
  What can I infer from this? Is the low
current string healthier, presenting higher impedance due to a higher
state of charge? Or is there a single bad cell with high impedance in
this string? Both, neither, something else, or can't know without
further information?
   
  
  Mark Frye
  
  Berkeley Solar Electric Systems
  
  303 Redbud Way
  
  Nevada City,  CA 95959
  
  (530) 401-8024
  
  www.berkeleysolar.com 
  
  

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[RE-wrenches] Imbalance In Multiple String Charging Current

2010-07-22 Thread Mark Frye

Folks,

I have three strings of batteries cabled in parallel to a common buss bar.

During charging, one string takes significantly less current than the
others.

What can I infer from this? Is the low current string healthier, presenting
higher impedance due to a higher state of charge? Or is there a single bad
cell with high impedance in this string? Both, neither, something else, or
can't know without further information?
 
Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City,  CA 95959
(530) 401-8024
www.berkeleysolar.com 

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[RE-wrenches] RETURN AMP SETTING

2010-07-22 Thread Dana

Chris Freitas of Outback can you chime in here?

 

Thanks,  Dana Orzel

 

Great Solar Works, Inc

E - d...@solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

Responsible Technologies for Responsible People since 1988"

 

From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Darryl Thayer
Sent: Wednesday, July 21, 2010 8:35 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] RETURN AMP SETTING

 


That is a good question, I have not an answer, but of course it should be based 
on the amp hour of the battery bank, absorb charging voltage, and of course the 
charging source in the case of generators.  Following Ron's advise start at C/5 
for SOC less than 50% then C/10 till about 70% SOC and then C/15 till 80% then 
C/20 to 90 %. the problem we have no way to set these values, Perhaps Ron could 
give is a routine?  The closet to SOC charging is the Outback and then the 
Magnum but both miss the goal.  

--- On Wed, 7/21/10, Dana  wrote:


From: Dana 
Subject: [RE-wrenches] RETURN AMP SETTING
To: "'RE-wrenches'" 
Date: Wednesday, July 21, 2010, 5:54 PM

As the % of full charge is related to the of degree absorption & gravity [the 
denser & more charged acid descending, and lighter acid rising] @ what point in 
the absorption would be prudent to stop charging?

 

I used to cut off the charge on the Trace SW series at 12 “return amps”, VS. 
the factory default I think was at 5 amps.  This has & continues to work well 
but I never had anyone really answer this function clearly.

 

Is there a battery manufacturer  or wrench that would care to comment on the:  

The minimum “Return” amps to disconnect for a “full” charge?

OR

The time required per 100 AHR after reaching the Absorption point setting for 
the mix to occur?

 

I realize that battery construction, battery condition, age and temperature and 
the current power usage will also play into this factor and it may not be a 
simple answer.

 

 

 

 

 

 Dana Orzel

 

Great Solar Works, Inc

E - d...@solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

Responsible Technologies for Responsible People since 1988"

 

From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye
Sent: Wednesday, July 21, 2010 4:25 PM
To: al...@positiveenergysolar.com; 'RE-wrenches'
Subject: Re: [RE-wrenches] Propane Generator, Dual Outback Inverters

 

Allen,

 

Can I infer that if you are shutting off the gen before charge rates drop in 
absorption that you are running only briefly in the absorb phase? Or do your 
charge currents remain high through out an extended absortion phase?

 

Perhaps you have plenty of PV which you rely upon to bring the batteries up 
through the absorption phase, once the gen is shut off.

 

I would be interest to learn more about your approach to this.

 

Thanks,

 
Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 
(530) 401-8024 
  www.berkeleysolar.com  

 

 

  _  

From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar
Sent: Wednesday, July 21, 2010 3:17 PM
To: re-wrenches@lists.re-wrenches.org
Subject: Re: [RE-wrenches] Propane Generator, Dual Outback Inverters

The Onan RS2 shown in the generators article in HP 131 page 98 has 
performed flawlessly as backup support to an Outback quad-stack of VFX3648s. 
Differences, however, are that this 20kW gennie charges four inverters, rather 
than two; the elevation is 6,600 feet for about a 20% output deration; there 
are no huge loads above charging draw; and the client is aware enough to shut 
it off before absorption reduces the charge rate - all different conditions 
than you have described, as the gennie is usually fully loaded and running in 
balance.

Darryl is right about the amount of words necessary.

Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com  

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.851 / Virus Database: 271.1.1/3008 - Release Date: 07/21/10 
00:36:00


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Re: [RE-wrenches] Propane Generator, Dual Outback Inverters

2010-07-22 Thread William Miller


Darryl:

There is a scenario in which problems occur:  If your loads exceed the 
generator capacity, the Outback system will fail.  The Xantrex inverters 
are superior in this scenario in that they will transition to invert mode 
to synchronize with the generator and support the generator as long as the 
batteries will sustain the operation of the inverter.


William Miller


At 12:21 PM 7/21/2010, you wrote:
The propane and gasoline generators both ar premixed combustion and have a 
low efficiency at part throttle/ part load.  The Diesel does the best job 
of maintaining efficency at low load.   The outback can control its 
charging current to the load limit of the generator.  If the AC loads need 
more power the Outback can reduce the charging rate until the AC load 
diminishes.


It takes a lot of words to describe and decide what is the correct 
generator sizing.

Darryl
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Re: [RE-wrenches] Propane Generator, Dual Outback Inverters

2010-07-22 Thread Jason Szumlanski

I should have been a bit more clear about my application. I'm not
worried about battery charging rates or load percentage on the
generator. I've already determined that this size generator will
normally run at a good efficiency level. I am more concerned with the
quality, longevity, and enclosure. I have a couple of applications in
mind, but my immediate need is for a mobile environment. The generator
might be subject to some degree of road spray and it will be used in a
near-ocean environment.

I've had some good and bad experiences with gas gennys. Someone
recommended an Onan, a brand I swore never to use again after I replaced
a $700 controller three times in a year (at my cost) and Onan was zero
help in trying to diagnose the problem. They tried to blame it on
surging when the inverter/chargers kicked in. Anyway, I'd be willing to
try again if I get some good feedback. Cost is always an issue, and I
know the Onan's can be pricey.


Jason Szumlanski
Fafco Solar

-Original Message-

Can you say something more about the system?  Is there a PV component?
What
is the size and type of the battery bank?

The thing I am beginning to understand about propane generators is that
there is a problem with Outback charging re: partial load efficiency.
If
the generator/chargers are sized to give a good C/10 bulk charge rate,
then
they will be running well below 50% load when they are providing a
desirable
absorption phase current. That's extended absorption run times at poor
generator efficiencies. This also plays into having a generator that is
sized for full AC loads and full charger currents. If you design for
this
case, but do not have large AC loads during charging, you will be well
down
into the 25% load on the gererator, very inefficient with propane.

I have had very good success with my Kohler 30kw REGZ 2-wire start
propane
generator in a lower elevation, California foothills location.

What exactly do you mean by harsh environment?

Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City,  CA 95959
(530) 401-8024
www.berkeleysolar.com 

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[RE-wrenches] aluminum heat fins for radiant retrofit...who's got 'em?

2010-07-22 Thread Mick Abraham

Hello, Wrenches~

Please see the photo on page 48 of the latest *Home Power* magazine (#138).
This shows aluminum fins with an extruded clip into which Rehau type radiant
floor tubing can be clipped.

Where can I get these parts for resale?

Have any of you observed an installation where this approach actually worked
OK? I'm sure the aluminum  fin would extract heat from the tubing OK but the
wood subfloor won't extract heat from the aluminum very quickly. Insulation
between the aluminum fin and the air below it might help, right?

My client wants to retrofit solar heat to an existing home which does not
have the in-floor radiant tubing embedded in lightweight concrete--the more
common way to do a radiant floor. He had planned to drive existing baseboard
radiators but the higher temperature which those require (compared to a
radiant floor) led to this pursuit.

Thanks in advance,

Mick Abraham, Proprietor
www.abrahamsolar.com

Voice: 970-731-4675
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Re: [RE-wrenches] RETURN AMP SETTING

2010-07-22 Thread Maverick Brown [Maverick Solar]

boB

Time for you to design an RTS that also measures SG.

Then my Classic can:
Set Return Amps automatically. 
Alert for an excursion in charge time
Alert for low water
Etc. 

Thank you,

Maverick


Maverick Brown
BSEET, NABCEP Certified Solar PV Installer ®
President & CEO
Maverick Solar Enterprises, Inc.
Office: 512-919-4493
Cell:512-460-9825

Sent from an iPhone. 

On Jul 21, 2010, at 9:56 PM, boB Gudgel  wrote:

> Darryl Thayer wrote:
>> That is a good question, I have not an answer, but of course it should be 
>> based on the amp hour of the battery bank, absorb charging voltage, and of 
>> course the charging source in the case of generators.  Following Ron's 
>> advise start at C/5 for SOC less than 50% then C/10 till about 70% SOC and 
>> then C/15 till 80% then C/20 to 90 %. the problem we have no way to set 
>> these values, Perhaps Ron could give is a routine?  The closet to SOC 
>> charging is the Outback and then the Magnum but both miss the goal. 
> 
> I would also be interested to hear Ron's answer to this, but I would think 
> that if you measure the current  and Specific Gravity
> together, during absorption , when the proper fully charged SG specification 
> is reached, you would have your RA answer.
> 
> Or, darn near close to it.
> 
> boB
> 
> 
> 
> 
> 
> 
> 
> 
>> 
>> --- On *Wed, 7/21/10, Dana //* wrote:
>> 
>> 
>>From: Dana 
>>Subject: [RE-wrenches] RETURN AMP SETTING
>>To: "'RE-wrenches'" 
>>Date: Wednesday, July 21, 2010, 5:54 PM
>> 
>>As the % of full charge is related to the of degree absorption &
>>gravity [the denser & more charged acid descending, and lighter
>>acid rising] @ what point in the absorption would be prudent to
>>stop charging?
>> 
>> 
>>I used to cut off the charge on the Trace SW series at 12 “return
>>amps”, VS. the factory default I think was at 5 amps.  This has &
>>continues to work well but I never had anyone really answer this
>>function clearly.
>> 
>> 
>>Is there a battery manufacturer  or wrench that would care to
>>comment on the: 
>>The minimum “Return” amps to disconnect for a “full” charge?
>> 
>>OR
>> 
>>The time required per 100 AHR after reaching the Absorption point
>>setting for the mix to occur?
>> 
>> 
>>I realize that battery construction, battery condition, age and
>>temperature and the current power usage will also play into this
>>factor and it may not be a simple answer.
>> 
>> 
>> 
>> 
>> 
>> 
>> Dana Orzel
>> 
>> 
>>Great Solar Works, Inc
>> 
>>E - d...@solarwork.com
>> 
>>V - 970.626.5253
>> 
>>F - 970.626.4140
>> 
>>C - 970.209.4076
>> 
>>web - www.solarwork.com
>> 
>>Responsible Technologies for Responsible People since 1988"
>> 
>> 
>>*From:* re-wrenches-boun...@lists.re-wrenches.org
>>[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
>>*Mark Frye
>>*Sent:* Wednesday, July 21, 2010 4:25 PM
>>*To:* al...@positiveenergysolar.com; 'RE-wrenches'
>>*Subject:* Re: [RE-wrenches] Propane Generator, Dual Outback Inverters
>> 
>> 
>>Allen,
>> 
>> 
>>Can I infer that if you are shutting off the gen before charge
>>rates drop in absorption that you are running only briefly in the
>>absorb phase? Or do your charge currents remain high through out
>>an extended absortion phase?
>> 
>> 
>>Perhaps you have plenty of PV which you rely upon to bring the
>>batteries up through the absorption phase, once the gen is shut off.
>> 
>> 
>>I would be interest to learn more about your approach to this.
>> 
>> 
>>Thanks,
>> 
>> Mark Frye
>>Berkeley Solar Electric Systems
>>303 Redbud Way
>>Nevada City,  CA 95959
>>(530) 401-8024
>>www.berkeleysolar.com  
>> 
>> 
>>
>> 
>>*From:* re-wrenches-boun...@lists.re-wrenches.org
>>[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
>>*Allan Sindelar
>>*Sent:* Wednesday, July 21, 2010 3:17 PM
>>*To:* re-wrenches@lists.re-wrenches.org
>>*Subject:* Re: [RE-wrenches] Propane Generator, Dual Outback Inverters
>> 
>>The Onan RS2 shown in the generators article in HP 131 page 98
>>has performed flawlessly as backup support to an Outback
>>quad-stack of VFX3648s. Differences, however, are that this 20kW
>>gennie charges four inverters, rather than two; the elevation is
>>6,600 feet for about a 20% output deration; there are no huge
>>loads above charging draw; and the client is aware enough to shut
>>it off before absorption reduces the charge rate - all different
>>conditions than you have described, as the gennie is usually fully
>>loaded and running in balance.
>> 
>>Darryl is right about the amount of words necessary.
>> 
>>*Allan** Sinde

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