[RE-wrenches] AC V DC RE: electrolysis

[William Miller]

Friends:



I have an installation of 12 Enphase IQ inverters that is downstream from a
generator transfer switch.  During power outages the generator will run
poorly when the Enphase is on and the sun is shining.  The problems go away
when the Enphase is shut off.  No surprises about this.



The Enphase is installed on a barn about 150 conduit feet from the
generator transfer switch.  My plan is to create a low voltage signal when
the generator is running and send it to a coil on a contactor in the barn.
Said contactor will disconnect the 12 micro-inverters.



There is existing one 26 AWG pairs of a Cat 6 cable running between the
buildings.  I have found a two pole, 30A contactor that draws 7 watts on
the coil.  The voltage drop calcs on 150 feet of 26 AWG wire shows a 24
volt signal will not cause excessive voltage drop (~4%).



Here is where I am uncertain:  Should I run 24 volts AC or DC?  My concern
about DC is if there are any damp connections, electrolysis will occur that
might erode the 26 AWG conductors.  We’ve all seen powder where copper used
to be.  Is AC less susceptible to electrolysis?  My research has turned up
no pertinent conclusions.



Thanks in advance.



William Miller



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985
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