On grid w/battery (was non wrenches) [RE-wrenches]

[Bill Brooks]

Rob,

Good to hear from you. I didn't think you would let me go with that broad
statement.

Although I am very supportive of MPPT systems, the devil is in the details.
Without some measure of MPPT effectiveness, I feel a whole lot more
comfortable with my stupid fixed voltage system. In California, temperatures
are generally warmer and sunnier so a dc/dc converter can have more negative
impact than positive--it depends on several factors. My SW system has been
working extremely well for nearly four years and it only gets off max power
in the winter when there is very little sun. My battery sits outside in the
shade so the battery temperature tracks much better with array voltage--that
works here but is impossible in much of the rest of the country. Other parts
of the country may experience different results.

I feel like your new MM-5 is setting the bar for what new inverters should
be able to do, but ruggedness and consistency is something that time will
tell (and good testing--like you have done). I'm still waiting to play with
an MM-5.

Bill.




-----Original Message-----
From: Rob Wills [mailto:RWills at AdvancedEnergy.com]
Sent: Monday, May 27, 2002 9:57 PM
To: RE-wrenches at topica.com
Subject: RE: On grid w/battery (was non wrenches) [RE-wrenches]


Hi Bill - your statement "a properly setup battery-based system will
harvest 95% or more.." may be true for hot climates, but for cooler ones,
and sites with lots of wind (module cooling), it can actually be greater.

Also 5% can be very significant - a 5% loss on a 3kW PV array at $6/Watt is
almost $1000 in PV module initial cost..

I'll do some testing in our lab and report on the difference for our 3kW PV
array, so we have hard data on this.

Rob Wills

-----Original Message-----
From: Bill Brooks [mailto:billb at endecon.com]
Sent: Monday, May 27, 2002 8:40 PM
To: RE-wrenches at topica.com
Subject: RE: On grid w/battery (was non wrenches) [RE-wrenches]


Joel and Marco,

With all do respect to my friends at Advanced Energy, the old SW is our most
stable inverter on the market. Joel, I think your unit could handle a much
larger array no problem. It seems that you have fallen into the trap of
believing that max power tracking has a lot to offer you. While I believe
there are benefits to MPPT, a properly setup battery-based system will
harvest 95% or more of what a MPPT controller will do. In fact, the Advanced
Energy MPPT or RV Products controllers will save little or nothing when
dealing with a floated battery (even so stated in RV Products' manual). Play
with your system some time and run the inverter up 4 or 5 volts (with the
C-40 set to max voltage) and you will find your power begins to drop, not
increase. It does depend on the array, but I would not be so quick to write
off the use of your unit. From what I remember being at your house, you did
not have a huge array. Stick with what works. The biggest issue with the old
SW was bad power factor when connected to the grid. I think you already
adjusted your machine.

Bill.


-----Original Message-----
From: Mangelsdorf, Marco [mailto:mmangelsdorf at hei.com]
Sent: Monday, May 27, 2002 5:13 PM
To: RE-wrenches at topica.com
Subject: RE: On grid w/battery (was non wrenches) [RE-wrenches]


Joel and others,

At the risk of sounding like a syncophant salesman for our friends at
Advanced Energy, Inc. in NH, their Multi-Mode battery-based 5 kW
inverter was designed to do exactly what the SW can't do: max power
point track.  Their inverter also uses no grid power at night to keep
the batteries floated.  I've been closely monitoring a number of
Multi-Modes in the field here in the tropics and the reports have been
very positive in terms of performance.

On another point: what's the latest with Xantrex getting UL listing for
the SW 4.2 with the GTI?   It's my understanding that the SW/GTI has
been approved by CTL in oh Canada but has yet to get official UL
approval.  Does anybody know anything otherwise?  Has anyone had any
difficulty getting their new SW/GTI assembly approved by the AHJ or
local utility?

aloha,
marco
ProVision Technologies, Inc.
Hilo, Hawai'i
www.provisiontechnologies.com

>From Joel Davidson:

The point is our battery bank has just sat there 35,000 hours keeping us
off the
PV array max power point and buying a float charge at night from the
grid for
less than 24 hours of relatively non-essential backup power.

Of course, I'd have to change inverters unless Xantrex figures out how
to get the SW4048 to max power point track when on the grid and function
as a
UPS in stand-alone mode during grid outages.

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

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

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

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

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

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

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

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

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

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

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

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

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

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

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

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

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

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

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

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
Or send an email to: RE-wrenches-unsubscribe at topica.com

T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================