contactor cuestions [RE-wrenches]

[Jeff Clearwater, Village Power Design]

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Hey All,

Solectria is going to release a PV Inverter series as well soon.  I 
got a tour and a sneak peak but I've signed a NDA, so I can't say 
much except to say that SMA and Xantrex and Sharp are soon to be 
joined by some good competition.  I liked what I saw!

Jeff C.
Village Power Design


>Marco,
>
>Xantrex says they will be including an automatically
>disconnecting contactor with all PV series inverters
>soon.  SMA's Sunny Central will also have this feature
>when it is released.
>
>The Sunny Central looks like it will be the superior
>product, but will only be available in one size at
>first.  The Xantrex guys are looking to improve their
>product as well.  I'm sure we'll hear from both
>manufacturer's soon, as this issue was addressed by
>both at Energy Outfitter's training conference in
>Vegas.
>
>Jerry Caldwell
>Light Energy Systems
>Concord, CA
>
>
>--- Marco <marco at pvthawaii.com> wrote:
>>
>>  Commercial grid-connected systems using the Xantrex
>>  PV series 3-phase
>>  inverters with their dedicated isolation
>>  transformers mean that there's
>>  going to be a not insignificant parasitic power loss
>>  during the nighttime
>>  hours.  According to my own measurements and
>>  conversations with others, this
>>  loss can somewhere between 3-5 percent, or even
>>  more, of the previous day's
>>  kWh production.  One way around these inverter and
>>  transformer core losses
>>  would be to install a three-pole contactor/relay
>>  that would disconnect the
>>  PV equipment in the evening and reconnect it early
>>  the following morning.
>>  The issues as I see them are: 1) extra cost for the
>>  labor, contactor and
>>  additional control electronics, and 2) additional
>>  means of system failure in
>>  case the contactor stays open.  One could use a
>>  photosensor to control the
>>  contactor or even a standard mechanical or digital
>>  timer. 
>>
>>  Has anyone out there gone this route of using a
>>  contactor?  Any feedback on
>>  the pros and cons?
>>
>>  thanks,
>>  marco
>>
>>  Marco Mangelsdorf
>
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-- 
~~~~~~~~~~~~~
Jeff Clearwater
Village Power Design Associates
Sustainable Energy & Water Solutions for Home & Village
http://www.villagepower.com
gosolar at villagepower.com

877-SOLARVillage
413-256-6777,  Fax 413-825-0372
61 Baker Rd
Shutesbury, MA 01072

PO Box 115
Boonville, CA 95415
707-895-9015, Fax 707-897-0024
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~

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