Xantrex PV versus Sunny Boy [RE-wrenches]

[mlafferty at universalenergies.com]

Marco wants to know (paraphrased):

What's better for a triple orientation, 30 kW PV System?  12 Sunnyboys
or Xantrex PV Series?

David B recommends (paraphrased):

Go with the Sunny Boys. Mppt better, 1 failure not 100% failure,
Isolation X-frmer losses 1-3% kWH AC, AC & DC Wiring smaller, faster,
cheaper, etc.

All:

Great question for this list.  My experience leans strongly toward
David's point of view, especially when in higher ambient temps....Like
Hawaii.

The Mppt window of SB's vs. PV's strongly favors the SB.  In addition,
SB's posted efficiency #'s (CEC list) can be believed.  PV's #'s don't
include the iso transformers, based on the data I have.  Of note is the
fact that the SB's overall DCV-ACV headroom at 208 VAC is greater,
yielding higher but undocumented (to my knowledge) kWH.  First
multi-system/multi-site 12 month Sacramento kWH/Capacity Factor data on
208 due in soon.... E-mail me OFFLIST at the end of August if you are
interested in the data.

Combining the triple orientation and related lower Vmpp associated with
it will further enhance the SB's Mppt advantage over the PV for the
described application. 

So far, the issues mentioned are more "Customer Satisfaction" related
than "Contractor Related".... Read this as "Easier to meet Customer
expectations with a clean conscience leads to reduced bad press and more
sleep!"  Or Surfing, as the case may be....

Additional factors are the NEC / UL realities of Combiners and DC
Fusing.  By using Square D Discos, 12 SB's will only require 4, 1 per
orientation, without a combiner (depending on the modules used). (Cost
of larger DC Disco, Longer DC Runs, Combiner(s), Fusing, Wiring, Conduit
& Labor is higher with the PV option.....Based on experience)

Using a 120/208 Sub-Panel with breakers as individual AC Disconnects
with a single larger AC Disco as the Utility Disconnect (If required -
You should know that if anybody does...) is most likely a slight cost
disadvantage to the SB.  When you factor in the minimum two AC Discos
required for the PV... One each side of the Iso X-frmer under Commercial
NEC requirements... (often overlooked) and the associated Wire, Conduit
& Labor, it's not as bad as it looks at first glance.

Array equipment grounding should be a wash.... 30 kW @ 208 is 30 kW @
208, after all. 

Combine all the factors....Throw in a SB Control and you are sure to
have a "Go Big Red" answer for this application.

Pray for Sun!

Matt Lafferty
Universal Energies Institute
mlafferty at universalenergies.com
(916) 422-9772
(916) 628-7694 Cell
(916) 914-2247 Fax
www.universalenergies.com

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