[RE-wrenches] 24 vs. 48

[Exeltech]

The most common reason to go with a higher
voltage (and thus lower current for a given
overall wattage) is to allow the use of
smaller conductors, which are generally
easier to work with, and lower cost.

There are fractional performance advantages
to 48V over 24V in *some* equipment, but the
advantages typically require lab-grade
equipment to measure.  Equipment such as
charge controllers and MPPT often benefit
from operating at a higher voltage due to
reduced energy loss in the copper.


The above aside, Nathan appears to have
mis-typed when he said:

> "Wire sizing might be reduced on the low
> voltage side of hings. 


Wire sizes *increase* for a lower-voltage
system at a given wattage and the same
conductor losses as in a higher-voltage
configuration.  A 24V system will have
double the current than a 48V system at
the same wattage.  Larger conductors are
needed if the loss is to be the same in
the 24V as in the 48V configuration.

Dan
Sr. Engineer
Exeltech




Dan


--- On Tue, 1/17/12, Nathan Jones <solardude97 at yahoo.com> wrote:

> From: Nathan Jones <solardude97 at yahoo.com>
> Subject: Re: [RE-wrenches] 24 vs. 48
> To: re-wrenches at lists.re-wrenches.org
> Date: Tuesday, January 17, 2012, 12:11 PM
> 
> 
> Mark,
> It would seem to be a wash. As the voltage is halved the
> amperage is doubled in the battery bank. This would seem to
> require doubling the charging amperage so nothing is gained.
> On a system of any size the 48 volt gets the default nod
> here. Charge controllers handle twice the solar. Parallel
> battery strings are eliminated, or at least held to two.
> Wire sizing might be reduced on the low voltage side of
> things. And much easier future expansion possibilities,
> too.
> Cheers,
> Nathan Jones
> Power Source Solar Inc
> 
> 
> ------------------------------
> On Tue, Jan 17, 2012 10:56 AM CST Mark Frye wrote:
> 
> > Not really on topic to Jay's question, but...
> >
> > Is 48v always better than 24v?
> >
> > How important is bulk charging current to overall
> > battery life?
> >
> > In some cases, isn't it better to use a 24v
> > inverter/charger which can develop a higher
> > charge current for a battery bank that
> > has a higher AH rating?
> > 
> > Mark Frye
> > Berkeley Solar Electric Systems
> > 303 Redbud Way
> > Nevada City,  CA 95959
> > (530) 401-8024
> > www.berkeleysolar.com