[RE-wrenches] AC coupled with grid and backup generator

[Darryl Thayer]

I have experienced the same thing with Outback and PVPowered.  
DT

--- On Tue, 7/28/09, Mark Dickson <mark at oasismontana.com> wrote:

> From: Mark Dickson <mark at oasismontana.com>
> Subject: Re: [RE-wrenches] AC coupled with grid and backup generator
> To: jryago at netscape.com, "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
> Date: Tuesday, July 28, 2009, 12:40 PM
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> Jeff,
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> I had this
> same hesitation when we first
> fired up our AC coupled system.  When speaking with
> Steve at outback and he was
> pretty sure that the generator would put out dirty enough
> power that the
> Fronius inverter would not like it and shut down.  He
> was correct—it goes into
> an error mode as soon as the geni kicks on.  Once the
> generator shuts down the
> Fronius senses the frequency is back within range and
> resets itself.  Turned
> out to be a simple solution and has been operating
> flawlessly for almost a year
> now. 
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> Good
> luck! 
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> Mark
> Dickson 
> 
> Oasis Montana
> Inc. 
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> From:
> re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org]
> On Behalf Of
> Jeff Yago
> 
> Sent:
> Tuesday, July 28, 2009 6:55
> AM
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> To:
> RE-wrenches
> 
> Subject: Re:
> [RE-wrenches] AC
> coupled with grid and backup generator 
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> We are completing a residential 4 kW solar system that is
> on the grid, but has
> backup battery-powered Xantrex 6 kW inverter, AC coupled
> Sunny-Boy inverter,
> and a 17 kW Kohler generator.  The larger generator is
> to allow operation
> of a ground-source heat pump during winter which is not
> supplied from
> the inverter fed panel.  We have added a relay
> cut-out for the Sunny
> Boy AC output to prevent over-charging the batteries during
> utility outage, but
> have some concerns about back-feeding the generator through
> the 100 amp 240 VAC
> transfer switch when the Sunny Boy thinks the grid is still
> up.   
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> Will the Sunny
> Boy try to couple to the generator like it
> will the inverter which will be feeding other house loads
> during an outage and
> if so, any risk?   We have wired an aux.
> switch contact on the
> transfer switch to also lock out the Sunny Boy output using
> the same relay
> control as being used for high battery voltage cutout, but
> this is adding other
> issues related to needing multiple relays due to different
> relay coil voltages. 
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> Anyone smoked a
> large generator by back-feeding from
> inverter when the loads are reduced or shut
> off? 
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> Thanks,
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> Jeff
> yago 
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> Netscape. 
> Just the Net You Need. 
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