mondo off-grid inverters [RE-wrenches]

[Jeffery Wolfe, Global Resource Options]

Having put together a couple of 500V battery banks, I can tell you it's
no fun. Even with what we learned in terms of better and safer design,
it's still no fun, and long strings get into some of the same problems
as massively parallel strings.

I've stopped wishing for a mid-voltage (say 100V) battery based system,
not enough call for it. Easier to do an Outback / Sunny Boy or Sunny
Island system if required due to long PV transmission distances.

And yes, the large inverters do weigh a lot and are difficult to
install. They also do not have the number of installs that someone like
Outback has, so the experience level of the vendors is far lower, a
critical factor in making things work.

We're sold on modular power systems. I'm sure there is a limit on what
I'd find acceptable, but it is beyond 30 kW.

Jeff

Jeffery D. Wolfe, P.E.
Global Resource Options, Inc., Solar Energy Solutions

-----Original Message-----
From: Christopher Freitas --- OutBack Power
[mailto:cfreitas at outbackpower.com] 
Sent: Thursday, September 07, 2006 9:50 PM

Marco - 

There are some large stand-alone inverters out there - but the
performance is usually surprisingly poor from a efficiency standpoint.  
Often the idle power consumption is in the 10% of the full power rating
(so 3000 watts for a 30KW unit) and they often weigh thousands of pounds
- real fun to move...  Most of them also are not "hybrid" meaning they
will not charge the battery either.  

We are fielding our first 36 KW three phase inverter/charger in the next
few weeks and have many single and split phase 30 to 36 kW off-grid 
systems in the field now - some for several years already.    

Keep in mind that for 36 kW you only need TEN OutBack VFX3648 inverters
- not the "dozens" you mentioned.  Our idle power draw will be as low as
65 W DC for a 36 kW unit depending on the AC output configuration.  
Since we can turn on the additional slave inverters with increased load
the efficiency is very good across the entire power range.  All of the
parts can be carried by one person and even installed solo.  

>From my experience and research - all of the large military or
commercial inverter you find will have a price that will be very high,
less features and the lead time and service response unacceptable for
most off-grid applications.  Most also will require high DC battery
voltages which introduces lots of design issues and safety concerns.  

I would be very interested in hearing other people's experience. 

Christopher


Christopher Freitas


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