Date: Sun, 17 Jun 2007 07:26:17 EDT
Reply-To: RAlanen@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Frank Condelli <RAlanen@AOL.COM>
Subject: Re: Solar panels for your Vanagon
Content-Type: text/plain; charset="US-ASCII"
In a message dated 16/06/2007 11:10:45 P.M. Eastern Standard Time,
LISTSERV@GERRY.VANAGON.COM writes:
Date: Sat, 16 Jun 2007 19:57:31 -0700
From: Michael Elliott <camping.elliott@GMAIL.COM>
Subject: Re: Solar panels for your Vanagon..
Hi Don,
Right on. I can't tell if generator people are oblivious, inconsiderate,
or some mixture of both.
To others considering a solar rig, I would suggest using wire thicker
than lamp cord to "remote" the panels. Low voltage systems are high
current systems, so wire resistance wants to be low in order to get as
much power from the panels to the battery. That means fat wire.
Lamp cord is usually pretty skinny stuff, like 22 gauge. A 15-foot
length of 22 gauge has about .36 ohms of resistance (send and return
combined). In my system, the panels might be delivering 4.7A @ 17 volts
in full sun. That's 80 watts. If I were using 15 feet of 22 gauge wire,
the voltage lost due to wire resistance would be .36 x 4.7 = 1.7 volts.
At 4.7 amperes, that's 4.7 x 1.7 = 8 watts lost as heat in the wire, a
10% loss.
Standard North American-style household grade ac receptacles and plugs
are supposed to have less than .03 ohm contact resistance -- when new.
That adds .06 ohm more resistance to the mix, with an additional 1.3
watts of loss.
11% may or may not be important, depending on your system. It's just
something to consider. I wanted the freedom to locate my panels pretty
far from the van, in case the good sunlight isn't conveniently close. I
use 6 gauge wire, and a 40-foot extension. That's just .028 ohm, giving
a loss of .6 watts passive wire loss. The PP75 Anderson Powerpole
connectors have only .0002 ohm of resistance.
--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR
Mike, thanks for this GOOD advice. This is information I had not previously
thought about. Where are you storing the 40' extension and how much space
is taking up ? AND, why 40' why not 50' or 100' ?
Cheers,
Frank Condelli
Almonte, Ontario, Canada
'87 Westy, '90 Carat, '87 Wolfsburg (Forsale) & Lionel Trains (_Collection
for sale_ (http://members.aol.com/Fkc43/trainsal.htm) )
_Frank Condelli & Associates_ (http://members.aol.com/Fkc43/busindex.html)
- Vanagon/Vanagon Westfalia Service in the Ottawa Valley
_Vanagon Stainless Steel Exhaust Systems_
(http://members.aol.com/Fkc43/stebro.htm)
_BusFusion_ (http://members.aol.com/BusFusion/bfhome.htm) a VW Camper
camping event, Almonte, ON, June 07 ~ 10, 2007
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