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

[Jason Szumlanski]

Does anyone know if an automotive style 12V relay coil can handle the
solar panel voltages common in a 12V nominal panel? This would be a low
cost and small size solution that might work best in my case. A $6 relay
can switch 40A - well over what I need to do. 

 

Jason Szumlanski

Fafco Solar

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mick
Abraham
Sent: Monday, January 31, 2011 9:43 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Photosensor for 12VDC System with load
controller

 

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

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20110201/90ee39d3/attachment-0003.html>