cost per kWh [RE-wrenches]

[Nick Nicholas, APS]

Hello Travis:
    We install KWH meters on our larger off-grid system.  Today, in our
shop, we are laying out a system which uses a KWH meter for each inverter
stack.
    These KWH meters are extremely useful in evaluating energy usage.
Plenty of manufacturers incorporate amp meters into their inverters, but it
is a little disappointing that we can't reveiw amp-hours on the inverters
inputs and outputs.
    I had a situation last year, in which a customer called me after first
moving into his new home.  He complained that his generator was running
frequently, and he questioned the solar arrays output.  We looked at what we
had estimated that he would be using from the original system sizing.  The
original estimate was for a system which would use 32 KWH in the winter
months and 42 KWH in the summer months.  The customer stopped complaining
when we read the KWH meters, which showed he was using more than 60 KWH per
day in those winter months.  After that, the customer actually adjusted his
usage to meet his original estimate.  Since then, he has only put a few
hours on his generator.
    The customer has quite the solar home.  He built an incredible 7,000 sq.
ft. off-grid home with 2,500 sq. ft. power building, which includes 12 KW of
modules, 4 SW5548 inverters, 30 KW Kohler gen set, 7,080 AH battery at 48
volts (350 KW of capacity.)  Some of the unique features of the system
include audio alarms at residence, ATS back-up of inverter stacks, KWH
meters, Polyphaser lightning arrestors, surge protection, and a custom DC
load center with battery disconnects for both inverters and batteries.
Nick Nicholas

            Nick Nicholas
            Chief of Engineering
            Alternative Power Systems, Inc.
            135 Colfax Ave. Grass Valley CA 959545
            530-274-0588 530-274-0589 530-913-5605
            aps at sbcglobal.net alternativepowersystems.com



Add this card to your address book

Alternative Power Systems
www.alternativepowersystems.com
aps at sbcglobal.net
135 Colfax Ave.
Grass Valley, CA 95945
(530) 274-0588 phone
(530) 274-0589 fax
----- Original Message -----
From: "Travis Creswell, Ozark Solar" <ozsolar at ipa.net>
To: <RE-wrenches at topica.com>; <RE-wrenches at topica.com>
Sent: Monday, June 02, 2003 5:29 AM
Subject: Re: cost per kWh [RE-wrenches]


> Does anyone install KWH meters on Off-Grid systems?  I'm planning on
> integrating one into the system I'm setting up right now.  Still unsure if
> I'll install one on the generator circuit feeding the inverters.
>
>
> Travis Creswell
> Ozark Energy Services
> ----------
> >From: "Don Loweburg, Offline" <i2p at aol.com>
> >To: RE-wrenches at topica.com
> >Subject: Re: cost per kWh [RE-wrenches]
> >Date: Sat, May 31, 2003, 3:45 PM
> >
>
> >
> >In a message dated 05/30/2003 1:25:35 PM Pacific Daylight Time,
> >billb at endecon.com writes:
> >
> >> I think the correct method is to use watts and an appropriate
adjustment
> >> factor rather than amps.
> >>
> >
> >Here's a seat of the pants estimating method I use for sizing battery
> >systems. Crude but comes closer than most of us would wish for stand
alone
> >systems.
> >Multiply STC array watts X Peak Sun hours - divide by two= AC KWH/day.
> >Don
> >
> >--
> >
>
> - - - -
> To send a message: RE-wrenches at topica.com
>
> Archive of previous messages: http://www.topica.com/lists/RE-wrenches/
>
> List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm
>
> Check out participant bios: www.mrsharkey.com/wrenches/index.html
>
> Hosted by Home Power magazine
>
> Moderator: michael.welch at homepower.com


----------------------------------------------------------------------------
----

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

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

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

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

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
==^================================================================
This email was sent to: michael_welch at sbcglobal.net

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

TOPICA - Start your own email discussion group. FREE!
http://www.topica.com/partner/tag02/create/index2.html
==^================================================================