PV combiner box protection [RE-wrenches]

[Darryl Thayer]

-----------------------------------------------------------
Let University of Phoenix make 2004 your year. Evening, 
weekend or FlexNet® classes – over 130 locations. Look 
into our programs and get the degree that gets you going!
http://click.topica.com/caaciq1bz8Qcsbz9JC9a/UOP
-----------------------------------------------------------




Hi All and Kurt
The module has a max fuse or breaker rating, this must
be followed.  We have all heard of the few fires that
were caused by a panel short circuit and all the
balance of the array dumping there energy into the
shorted module.  So the Module must be protected from
overcurrent, hence the UL maximum current/fuse/breaker
rating.  

By code this is a maximum parallel or series
fuse/breaker or a supplementary fuse in each panel.  

And the bringing of perhaps 8 parallel sets of wires
down to the controllers/inverters leads to the single
motion of the hand switch that I fought with for so
long.  (in my case 16 breakers at the enterance to the
building)  
 
Thanks daryl

--- Kurt Nelson <sunwise at cheqnet.net> wrote:
> Greetings all,
> 
> I think this will be an easy one and not a can of
> worms, but then....  
> 
> A friendly competitor and I were speaking at the
> energy fair a while
> back and we disagreed on some issues regarding array
> wiring and over
> current protection. 
> 
> My position would be that the use of over-current
> protection
> (fuses/breakers) within the combiner box at the
> array is to protect the
> series and parallel interconnect wiring of the PV
> array which is
> typically a much smaller gauge wire than the home
> run (this primarily
> concerning low voltage 12, 24 & 48V systems).
> 
> If a properly sized breaker or fuse is used at the
> DC box before the
> charge controller (protecting the array wiring from
> any high currents
> generated in the home/battery), and if the home run
> AND interconnecting
> wiring is capable of handling the total short
> circuit current of the
> entire array, is it necessary to have fusing in the
> combiner box?
> 
> For instance if you had two 75 watt PVs wired into
> either a 12 or 24
> volt array and the smallest wire in the PV circuit
> was 10 gauge, would a
> fuse be required at the array if a properly sized
> fuse was used within
> the home prior to the charge controller?  BTW, I
> always use a second
> fuse/breaker between the CC and the battery.
> 
> Also, as in the 12 volt configuration mentioned
> above but expanded a
> little.... a 600 watt, 24 volt array consisting of
> eight 75 watt
> modules.  I would think it acceptable to bring four,
> two series sets
> into one module's J-box (using liquid tight w/ten
> gauge/another post)
> and then use 10/4 SO(w) to bring the whole array (as
> two paralleled
> series sets) down to the pole mounted combiner box
> from the
> tracker/movable/seasonally adjustable top-of-pole
> mount.  I'd then use
> two FRN-15s in the combiner box before the
> distribution block/home run
> (necessary?).
> 
> In any case, I've been told that you have to bring
> each series string
> down individually, resulting in eight conductors
> between the rack and
> the mast and nothing less than spaghetti in a
> similar 12 volt system.
> I'm hoping this is wrong and wondering what the
> logic is otherwise.
> Thanks for your brains.
> 
> Kurt Nelson
> SOLutions



		
__________________________________
Do you Yahoo!?
New and Improved Yahoo! Mail - Send 10MB messages!
http://promotions.yahoo.com/new_mail 

-----------------------------------------------------------
Give Your Team Access to Their PCs from Anywhere. Increase 
productivity with a secure remote-access solution from 
GoToMyPC Pro. Stay in touch with your office. FREE TRIAL:
http://click.topica.com/caaciqXbz8Qcsbz9JC9f/ExpertCity
-----------------------------------------------------------

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & etiquette: www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------