[RE-wrenches] Demand savings from PV FYI

[Darryl Thayer]

You are correct Peter, however that day did not occur during the year of record.  The highest billed utility peak was reduced and the highest peak that could have occurred was reduced.  The highest billed peak did occur sort of like you describe, a collapse of sun on a day that was hot.  However that peak was not the highest peak that would have occurred.  Next year or even this summer that is in progress may have a day like you describe, but it I think would be unlikely.  

Just some numbers, the summer demand with fees is about $12/kW
the Winter is about $9/kW 
The ratchet is about $4/kW for following 11 months 

Darryl 

--- On Sat, 6/26/10, Peter Parrish <peter.parrish at calsolareng.com> wrote:

> From: Peter Parrish <peter.parrish at calsolareng.com>
> Subject: Re: [RE-wrenches] Demand savings from PV  FYI
> To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
> Date: Saturday, June 26, 2010, 3:25 PM
> Darryl,
> 
> I'm sure what you say is generally true, but unless your
> utility has an
> enlightened tariff, I still think we have a problem.
> 
> Since the demand charges are based on the highest demand
> recorded on a
> trailing 12 month basis, what happens on that one sunny hot
> day when a cloud
> passes in front of the sun for 15 minutes and the recorded
> demand for that
> time period is recorded and the demand then snaps back to
> historical values.
> 
> In SCE territory, I believe, the demand charge gets pegged
> at that value for
> the next 12 months, regardless.
> 
> Please explain to me anything I'm missing.
> 
> - Peter
> 
>                
>                
>                
>      
>  Peter T. Parrish, Ph.D., President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com 
> 
> Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
> 
>  
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org]
> On Behalf Of Darryl
> Thayer
> Sent: Saturday, June 26, 2010 7:21 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] Demand savings from PV FYI
> 
> Hi all
> A while back we had a thread going on demand savings from
> PV.  I reciently
> viewed a 1 year data set.  The PV Savings were $36/
> month on energy and
> almost $100 a month on Demand.  The company is a small
> business with lots of
> computers and of course air conditioning  We are
> blessed with a diurnal temp
> swing.  so morning are cool, and economizers are
> effective.  The builoding
> does not have building automation system.
> 
> The summer demand is by far the highest, Every monthly peak
> occured in the
> afternoon, The highest peaks were on sunny days in the
> afternoon, the solar
> reduced all the highest demand peaks.  The Demand fee
> structure is both a
> monthly charge and a ratchet that follows the highest peak
> for 11 months.
> The system is 12 Outback inverters. 
> 
> BTW the smud program with Silent Power should reduce both
> utility and
> customer demand charges.   
> 
> 
>       
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