[RE-wrenches] off grid PV connected to generator

[August Goers]

Hi All --



Thanks for the feedback. Yea, we've always used Sunny Islands with
batteries for anything that needs to run off grid. This was more of just a
theoretical question. From what I heard, it sounds like the excess current
from the PV might damage the generator (or I suppose anything running in
the house) and this will result in higher voltage. Best case, the inverter
will cycle on and off. V = I*R. Worst case something blows up.



Thanks, August



*From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Greg Seelhorst
*Sent:* Wednesday, December 12, 2012 8:18 PM
*To:* 'RE-wrenches'
*Subject:* Re: [RE-wrenches] off grid PV connected to generator



August –



I’ve seen this scenario and it is not pretty like William suggests.



>From what I’ve seen, the problem is not so much the power of the PV being
more than the generator, but moreso if the 1) generator is synchronous or
non-synchronous with the inverted AC (sine wave) and 2) if the loads are
less than the PV.   The generator will ‘create’ the voltage and run even if
there are zero loads.  The inverted AC (from PV) wants to push current onto
the ‘local grid’ and if there are no loads (nor heat sink diversion or
batteries to charge) then the current will try to backfeed the generator.



My recommendation is to get a critical loads panel for the generator only
back-up, or go grid-tie with back-up using a Sunny Island, or the like,
that make the switch seamless during an outage.



*Greg Seelhorst*

*Designer/Project Manager*

NABCEP Certified Solar PV Installer™



*POSITIVE ENERGY, Inc.*

510 S. Main Street

Las Cruces, New Mexico 88001*
*Cell: 575-650-1883

Office: 575-524-2030

FAX: 575-915-1788



*gs at PositiveEnergySolar.com* <gs at PositiveEnergySolar.com>
www.positiveenergysolar.com </www.positiveenergysolar.com>



*[image: http://www.positiveenergysolar.com/images/stories/PE-logotype.png]*<http://www.positiveenergysolar.com/>
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