[RE-wrenches] Back-up from large grid-tie system.

[Mick Abraham]

Hello, Holt et al~

If the client only expects 24 hour autonomy, you could build/supply an
"uninterruptible power supply" for the police loads only, with no solar
recharge dedicated to that system. This would involve inverter/chargers,
appropriate safety gear & some monitoring, and a battery bank big enough to
carry those loads for the requested 24 hours...and no PV array.

When the grid comes back up, that will drive recharge of the battery. If the
client had requested, say, seven days of system autonomy that might point
back to connecting up PV to the system, but for 24 hours of ride-through I
think it's all about the battery...or the generator system with auto
transfer switch per William's suggestion.

Jolliness,

Mick Abraham, Proprietor
www.abrahamsolar.com

Voice: 970-731-4675


On Mon, Feb 1, 2010 at 1:42 PM, <holtek at sbcglobal.net> wrote:

>  William,
> I would agree with generator only if there was the load demand. One thing I
> failed to mention is that this will be back-up for lights and communication
> for the campus police w/ 24hr autonomy. It looks as though the Sunny Island
> route is the most practical at this stage, but I am open for other
> suggestions.
>
> Holt E. Kelly
> Holtek Fireplace & Solar Products
> 500 Jewell Dr.
> Waco TX. 76712
> 254-751-9111
> www.holteksolar.com
>
> ----- Original Message -----
>  *From:* William Miller <william at millersolar.com>
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Cc:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Sent:* Monday, February 01, 2010 12:18 PM
> *Subject:* Re: [RE-wrenches] Back-up from large grid-tie system.
>
> Kelly:
>
> A big a** generator and a transfer switch.
>
> William Miller
>
> PS:  Seriously, I have seen projects like this and rarely is there a
> natural subdivision in the power distribution that allows one to back up a
> portion of the loads.  Backing up a huge power demand, which I assume this
> is, is best done by rotating machinery.
>
> Wm
>
>
>
> At 07:52 AM 2/1/2010, holtek at sbcglobal.net wrote:
>
> Project:
> 43kw system originally designed as grid-tie. 208 3ph, 6 SB7000(208).
> Equipment already rec'd.
> The curve ball.....client now wants some back-up capabilities that include
> solar......there is a 7.92kw sub-array in the system that may be part of the
> solution. Any thoughts?
>
>
>
> Holt E. Kelly
> Holtek Fireplace & Solar Products
> 500 Jewell Dr.
> Waco TX. 76712
> 254-751-9111
> www.holteksolar.com
>
> ----- Original Message ----- From: "Peter Parrish" <
> peter.parrish at calsolareng.com>
> To: <re-wrenches at re-wrenches.org>
> Sent: Sunday, January 31, 2010 5:19 PM
> Subject: [RE-wrenches] Couple of Qustions about AGM batteries
>
>
> We have put together a 850 Wdc portable stand-alone PV system. It uses a
> Blue Sky 3024DiL charge controller, a pair of SunXtender 250 A-hr AGM
> batteries (24 volt configuration), and a Xantrex Prosine 1000 inverter.
>
> We have been using this system for powering "events" and getting some good
> marketing from the activities. Everything has worked out well, and the
> system is not being used now and probably won't until March or April
> sometime.
>
> We have let the system fully charge the batteries through bulk/absorption
> and now float. The float conditions are 26.4 V and 2.0 A at a battery
> temperature of 21 deg-C.
>
> My first question: is it alright to let the batteries float every day for
> the next 6 to 8 weeks, or should I disconnect them from the rest of the
> system until we are ready to use the system again?
>
> My second question: since the 3024iL can perform an equalization, is there
> a
> safe equalization procedure for these AGM batteries?
>
> - 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
>
>
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> *Please note new e-mail address and domain:
>
> *William Miller
> Miller Solar
> Voice :805-438-5600
> email: william at millersolar.com
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