[RE-wrenches] Generators and Grid-tie Systems

[Darryl Thayer]

Hello all 
I am under a time line so I do not have time to review until later.  But I have tried a few times and I can not ever get a grid tied inverter to sync with a generator.  I have been successful with bimodal (Battery based)inverters in a varied ways. (Apollo, Outback, Xantrex)  

A word of caution, a generator in parallel with an inverter can give strange voltage spikes.  This is the same as with inverters for mortor drives (never try this with a modified sine wave, and the voltage spikes may be why some people have reported damage to generator boards) . 

Darryl 

--- On Tue, 3/2/10, Jason Szumlanski <Jason at fafcosolar.com> wrote:

> From: Jason Szumlanski <Jason at fafcosolar.com>
> Subject: Re: [RE-wrenches] Generators and Grid-tie Systems
> To: re-wrenches at lists.re-wrenches.org
> Date: Tuesday, March 2, 2010, 1:22 PM
> While inverters are supposed to work
> this way, and do so very well on
> the grid, have any inverters been formally TESTED with
> various
> generators to confirm the theory?
> 
> Anecdotes and theories are not enough. Until there are
> TESTS and
> guarantees from inverter manufacturers that expensive
> generator control
> boards will not be damaged, I would err on the side of
> caution. Get a
> waiver from your customer if they insist you connect on the
> load side of
> the generator transfer switch. I doubt you will get an
> independent P.E.
> to sign off on it and take the liability. I could be wrong,
> but........
> why risk it?
> 
> Jason Szumlanski
> Fafco Solar
> http://fafcosolar.com
> 
> -----Original Message-----
> 
> 
> All,
> 
> If the grid-tie inverter is operating under UL1741 (and
> therefore
> IEEE1547),
> then the inverter has to cease output within 1 second of
> the voltage
> going
> over 10% of the base voltage.  So in the case where
> the generator is
> outputting and the load is less than the inverter output,
> the voltage
> will
> rise and the inverter will cease to ouput.  The
> voltage will then drop,
> the
> inverter will reconnect, and the cycle will repeat
> itself.  That assumes
> the
> generator's waveform is clean enough for the inverter to
> connect to in
> the
> first place.  James Worden from Solectria Renewables
> covered this
> briefly in
> a SolarPro article:
> http://solarprofessional.com/article/?file=SP2_5_pg16_QandA_2.
> 
> - Mike
> --
> Michael Kelly
> Project Manager / Project Engineer
> NABCEP Certified Solar PV Installer ?
> 
> SolarFlair Energy, Inc.
> 11 Mayhew Street
> Framingham, MA 01702
> Direct Mobile: 617-899-9840
> Main Phone: 508-293-4293
> Main Fax: 508-293-4003
> mike at solarflair.com
> 
> 
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