[RE-wrenches] Generators and Grid-tie Systems

[Jason Szumlanski]

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.
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Main Phone: 508-293-4293
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