[RE-wrenches] Photosensor for 12VDC System with load controller

Mick Abraham mick at abrahamsolar.com
Mon Jan 31 06:43:28 PST 2011


Maverick's suggestion would give the opposite action to what the original
poster needs. The C12 "night light" function turns the load on after dark
but Jason needs the opposite.

The solar array can serve as your "photocell", Jason. The PV +/- terminals
in the C12 controller have no power on them at nighttime (check me on that
with your voltmeter), but they are energized when there is sunshine. A relay
coil connected parallel to the the PV +/- terminals on the C12 should fire
when the sun is up and that coil would then release at sundown. Use a
"single pole single throw normally open" relay with a DC coil, and connect
the positive leg of your DC load across the normally open connection screws.

Make sure the relay coil can accept a wide range of DC input, since it may
encounter 20 volts across a 36 cell PV module when the sun first comes up.

Jolliness,

Mick Abraham, Proprietor
www.abrahamsolar.com

Voice: 970-731-4675


On Mon, Jan 31, 2011 at 6:52 AM, Jason Szumlanski <Jason at fafcosolar.com>wrote:

> I have a customer with a Xantrex C12 charge controller with LVD controlling
> a 5A load. Their battery and PV are not large enough to run the load 24/7,
> and they don’t need it to run at night. I am thinking about recommending a
> photocell to disconnect the load at dusk and turn it back on at dawn. They
> are not interested in upgrading the PV and battery (too costly).
>
>
>
> Can anyone recommend a photosensor source, and maybe a model number?
>
>
>
> Other ideas welcomed…
>
>
>
> Jason Szumlanski
>
> Fafco Solar
>
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