Advise sought for large off grid PV system; 480 volt 3-phase [RE-wrenches]

[Walt Ratterman]

Larry:

Walt Ratterman here.  I might be able to give you some assistance, but I
don’t want to hold you up either.  I do a lot of this kind of work, but
generally it is overseas.  Specifically, we are doing fairly large solar /
diesel hybrid systems in Rwanda to provide electricity for laboratories and
emergency lighting, and water pumping.  

I am getting ready to get on a plane in the morning to Burma to work on some
much small PV systems for clinics there, but I will have email on and off
for a bit.  If you still need assistance after the others respond, let me
know.

Walt Ratterman
wratterman at sunenergypower.com



-----Original Message-----
From: larry crutcher [mailto:larry at starlightsolar.com] 
Sent: Tuesday, March 27, 2007 1:59 PM
To: RE-wrenches at topica.com
Subject: Advise sought for large off grid PV system; 480 volt 3-phase
[RE-wrenches]


RE-Wrenches,

I am designing an off grid PV system and am looking for input and 
recommendations from experienced installers. Although I have years of 
building battery based systems, this is a big one. The customer has been 
running 60kW diesel generators 24/7 for about 2 decades. They want a PV 
system with batteries that will allow the generators to be shut down 
during the winter and low load periods. Summer loads can be above 
500kWhs per day but winter drops to less than 100kWhs which I can do 
with PV's.

Power details: The site has 480 volt, 3-phase Y distribution and 6 
transformers. There are only two 480 volt distribution circuits leaving 
the generator building. I have failed to locate power equipment that 
will produce 480 volt 3 phase for off grid use. Telecom equipment does 
not look suitable. I have found inverters to produce 60 kW @ 208 volt 3 
phase (Exeltech) and a 75 kva step up transformer for 480Y. I don’t like 
the transformer idea. The generator must be available at any time to 
take over loads. I am thinking of transfer switching @ 480 volts. I 
really would like automation for generators, battery charging, and 
transfer switches.

One generator is scheduled for rebuild and it will have auto-start added 
to it. The site has room for several large ground mount arrays of PV. 
Wind power does not look viable, < 5 m/s @ 30 meters. I am in a desert 
location that has very high ambient temperatures above 115°. A building 
for the batteries and inverters will be climate controlled to 80° F. 

So, how would you propose a solution for this type of site? Do you know 
where I can get 480 3-phase inverters?

Next post I'll ask about batteries, BIG batteries. No, even bigger!

Larry Crutcher
Starlight Solar


- - - -
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



__________ NOD32 2148 (20070327) Information __________

This message was checked by NOD32 antivirus system.
http://www.eset.com


- - - -
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
--^----------------------------------------------------------------