Adding battery backup to existing grid-tie PV system [RE-wrenches]

[Jeff Clearwater]

<x-flowed>

Hi William,

Yes I would also recccomend you look at using a Sunny Island.  That 
way you get all of the PV output available (well all one SI can 
handle which is about 5KW of PV on SBs) and don't have to do relay 
control which is iffy.  You'll find the price is not much more when 
you consider the SI includes the DC disconnect.

Also you say 4 (8D) batteries.  I was under the impression that 8Ds 
aren't true deep cycles - more of an industrial starting battery for 
CATS and such.  And you might want maintenance free batteries for 
these folks.

Hope that helps!

Best,

Jeff C.



>We have a customer from a several years back who bought a larger 
>system (~7kW AC system) which used 3 SMA 2500 and 1 SMA 1800 
>inverters... they always wanted battery backup, but given their high 
>end, low maintenance lifestyle, I wasnot eager to throw a pile of 
>batteries, miles of heavy 48 volt wiring, and dual SW inverters at 
>this application. But when they called a couple months ago 
>discussing their extended and unseemly LADWP power outage frequency, 
>and apparent willingness to let go of the whirlpool, sauna, wine 
>chiller, outdoor light show, and multi-level HVAC refrigeration 
>system (at least during power outages), I took note.
>
>Rather than dig in and rewire the PV array (or alternately), install 
>a backup power system that didn't use the PV system... we came up 
>with an interesting compromise:
>install (1) new Outback GVFX inverter with (4) 8D deep cycle batteries,
>this inverter is directly grid-tied, like the existing SMA inverters.
>On the (backed-up) load side of the inverter, we conneced the frige, 
>a few lights, computers, and a couple other important items. In 
>addition, we reconnected the (1) SMA 1800 inverter onto the load 
>side of the outback. When the outback is online (whether grid-tied 
>or standalone) the SMA inverter feeds in power to offset emergency 
>loads (and even charge the batteries if the power draw is lower than 
>solar output).
>
>This approach requires redundant inverter capacity (extra cost), but 
>allows the PV array to be wired at high voltage, enabling a larger 
>array and longer electrical feeder distances if needed.
>
>I'm thinking that this is a reasonable compromise solution (cost, 
>labor, performance...) for us to use as a retrofit/upgrade on older 
>systems, as well as a decent way for us to furnish battery backup 
>power with systems that wouldn't otherwise be compatible (Sunpower).
>
>I'm sure others have already done this... were you satisfied with 
>the results? Any issues of note?
>
>
>/wk
>
>
>- - - -
>To send a message: RE-wrenches at topica.com
>
>Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read
>
>List rules & how to change your email address: 
>www.mrsharkey.com/wrenches/etiquette.php
>
>Check out participant bios: www.mrsharkey.com/wrenches/
>
>Hosted by Home Power magazine
>
>Moderator: michael.welch at homepower.com


-- 
~~~~~~~~~~~~~
Jeff Clearwater
Village Power Design
Sustainable Energy & Water Solutions for Home & Village
http://www.villagepower.com
gosolar at villagepower.com
NABCEP (tm) Certified Solar PV Installer

530-470-9166
877-SOLARVillage
877-765-2784
72 Baker Rd.
Shutesbury, MA 01072
425 Nimrod St.
Nevada City, CA 95959
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~


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

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

List rules & how to change your email address: www.mrsharkey.com/wrenches/etiquette.php

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

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

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

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------

</x-flowed>