[RE-wrenches] Generators and Grid-tie Systems

[Michael Kelly]

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


On Tue, Mar 2, 2010 at 9:29 AM, Drake Chamberlin <
drake.chamberlin at redwoodalliance.org> wrote:

> I was recently told by SMA that in the event that the inverters did connect
> to generator output, and the load was less than the inverter output, that
> the voltage would rise and the inverters would fall off line.  A year or so
> before I'd been told by another SMA representative that generator circuit
> boards had been fried by inverter backfeed.
>
> It would  be very good to get to the bottom of this one.
>
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