On grid w/battery [RE-wrenches]

Bill Brooks billb at endecon.com
Tue May 28 22:10:41 PDT 2002


John, 

It's actually "Da Nile ain't just a river in Egypt." Mark Knopfler

Bill.

-----Original Message-----
From: jberdner at sma-america.com [mailto:jberdner at sma-america.com]
Sent: Tuesday, May 28, 2002 6:55 PM
To: RE-wrenches at topica.com
Subject: RE: On grid w/battery [RE-wrenches]


Bill:

Yes, I am sure this guy was a complete idiot and didn't know what the
heck he was measuring.  And Da Nile is a river in Egypt.

Fortunately, we have a contract with SMUD and one of the items will be
to determine the performance differential between battery based fixed
voltage grid tied systems and a straight MPPT systems.  We do know how
to measure things and our results will be conclusive.

Regards,

JSB

 -----Original Message-----
From: Bill Brooks [mailto:billb at endecon.com] 
Sent: Tuesday, May 28, 2002 3:24 PM
To: RE-wrenches at topica.com
Subject: RE: On grid w/battery [RE-wrenches]

John,

Are we talking power or energy here? 30% at night--no way that's right.
(he's probably measuring current and not power factor) 50% of power (or
energy)--sounds like this guy's system is totally screwed up or high
data
acquisition is screwed up.

I thought you guys were developing just such an animal--no more?

Bill.

-----Original Message-----
From: jberdner at sma-america.com [mailto:jberdner at sma-america.com]
Sent: Tuesday, May 28, 2002 3:00 PM
To: RE-wrenches at topica.com
Subject: RE: On grid w/battery [RE-wrenches]


Wrenches:

I have some data from a module manufacturer which compares the output of
two systems in Sacramento, CA. One is for an SW with batteries operating
in surplus sale mode.  The other system is a Sunny Boy grid tied system.

This is their data, not mine, so I can not publish it without permission
(which I will try to get).  In summary, the SW system produced about 80%
of the output of the Sunny Boy (arrays normalized to kWh per kW).
Unfortunately you loose another 30% in tare losses at night so the net
effect is that the battery based system is producing about 50% of the
power of the straight grid tied system.

As my boss in Germany says:

If you want a PV system then buy one.
If you want a UPS system buy one of those too.

Best Regards,

John Berdner


-----Original Message-----
From: Joel Davidson [mailto:joeldavidson at earthlink.net]
Sent: Monday, May 27, 2002 6:39 PM
To: RE-wrenches at topica.com
Subject: Re: On grid w/battery [RE-wrenches]

Bill,
If I go with a non-battery inverter, I'd keep my SW4048 and use it for a
non-PV
UPS. The SW harvests 2700 kWh/year, but I wouldn't mind another 135
kWh/year
plus approx. 80 kWh/year that the SW consumes floating the battery at
night. I
think a non-battery inverter would harvest approx. 3000 kWh/year from a
2200 WDC
STC array at a 12 degree tilt in Los Angeles. Does anyone still use the
old
UT-SW4048PV non-battery model? If yes, what size array and how many kWh?

Bill Brooks wrote:

> Joel and Marco,
>
> With all do respect to my friends at Advanced Energy, the old SW is
our most
> stable inverter on the market.

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