FW: Post For Wrenches....Xantrex versus Sunny Boy Thread [RE-wrenches]

Tue Aug 12 14:58:04 PDT 2003

Hello all, 

As most of you know I no longer work at Xantrex.  I do, however, have
friends who do and one of them, Lloyd Gomm has asked me to post the
email below to our forum.  I think Lloyds' message is well in keeping
with other manufacturers posts, somewhat infomercial, but generally good
and factual information.  Hence with no further ado below is Lloyds post
to Wrenches.

Regards,

Ezra
DragonSun Consulting
Morewater Road
Lasqueti Island, B.C. V0R 2J0

ezra at lasqueti.net
250 333 8650 voice
250 333 8670 fax 
-----Original Message-----
From: Lloyd Gomm [mailto:Lloyd.Gomm at Xantrex.com] 
Sent: Tuesday, August 12, 2003 1:59 PM
To: 'ezra at lasqueti.net'
Subject: RE: Post For Wrenches....Xantrex versus Sunny Boy Thread

	Ezra, given that Roy is on vacation.  Could you post this on our
behalf.  I would like the wrenches to have a different view...based on
some fact.  It's unfortunate that our response is latent, but what can I
do?  Roy was away last   week as well.   

	 Thanks! 

	--------------------------- 
I want to address what I believe to be some common misconceptions about
the PV series product line and how it stacks up to our competitors.

	1) Continuous Inverter Power @ 208 VAC 
<I'd much prefer to use one inverter rather than (12) 3-phase
SB2500s.> previous post on Wrenches 
According to posted specs...the SB2500 is limited to 2200 watts peak
(1850 watts continuous) when used in a 208 volt 3 phase application.
This means more inverters (16+ SB2500) and more capital cost to get to a
30 kW capacity.

	2) Thermal Performance 
The PV series produces full output power to 50 degrees C, while the
SB2500 starts derating power at a far lower ambient temperature.  

	3) Inverter Efficiency 
<The IGBT technology and electronics used has very high losses at less
than full
load.> previous post on Wrenches 
This is false.  The Sunny Boy and the PV Series use similar technology:
a high frequency IGBT-based bridge with a low frequency (60Hz) output
isolation transformer.  The shape of the efficiency curves are the same.

	4) Isolation Transformer Loss 
<Also the need for an isolation transformer is a waste of energy. You
will probably lose 1-3% of max output in the transformer. > previous
post on Wrenches 
Yes, the isolation transformer remains energized 24 hours a day.  With
electricity rates, insolation and net metering, conservatively this
results in about $1.00 of additional consumption for every $40.00 of
revenue produced by the PV system.  This needs to be a consideration of
life cycle cost, as does the higher capital cost of using multiple
string inverters.  Here are some quick numbers...

	Assuming a capacity factor of 20% (conservative for a commercial
system), the 30KW PV System should generate approximately 52,560 kWH per
year.  

	Assuming a 1% no load transformer loss, the PV system will lose
1,314 kWH per year due to night time tare. 
At 13 cents per kWH this equates to $170 dollars lost over $6,833
dollars generated (2.5%). 
For the 30 KW system Marco would require (30kw / 1,850 continuous) 16+
Sunny Boy inverters. 
Now lets consider the cost of the hardware. 
Mark at Alternative Solar Products sells both the PV Series and SMA
inverters to dealers.  He quoted the following prices.

	PV30 (with 5 year warranty and transformer cost included), cost
to dealer = $19,272 
SMA SB 2500U SBD 208, cost to dealer = $2,040 
So Xantrex cost is $19,272 vs. (2,040 * 16 units) $32,640.  So a dealer
is to invest an additional $13,368 to avoid $170 per year in transformer
loss?  

	I fully realize there are other system considerations an
installer must take into account.  However, much has been written about
night time transformer loss and I simply wanted to illustrate the real
cost in the context of the whole system vs. competing alternatives.

	 BTW..., if multiple string inverters are to be used in a 480
VAC applications, a step-up transformer is required between the Sunny
Boys and the grid.  This transformer has core losses associated with it
(just like the PV Series isolation transformer) and the Sunny Boys have
no means of disconnecting it at night.

	Ezra, thank you for posting this on Xantrex's behalf.  

	Brand X and proud of it! 

	Lloyd Gomm 

[Non-text portions of this message have been removed]

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