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<p>I'm bumping it up to a pair of 50 watt modules, I don't want to
go bigger because I need to fit them behind some shutters that
will cover them in the summer. To answer Bill's questions, the
site is at 10,000 ft, about a 1:12 pitch, so its definitely going
to pile up snow. We had snow sitting this year there into May.</p>
<p>Thanks,<br>
</p>
<pre class="moz-signature" cols="72">Ray Walters
Remote Solar
303 505-8760</pre>
<div class="moz-cite-prefix">On 10/9/18 8:57 AM, Drake wrote:<br>
</div>
<blockquote type="cite"
cite="mid:20181009145803.8F353107089@pdx1-mailman03.dreamhost.com">
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We have an AC coupled backup system at our house in S.E. Ohio. In
the winter we have many cloudy days. We are using two 40 W Sunwise
modules in series with a Morningstar PWM CC to maintain a 415 AH,
24 V
set of Full River AGM batteries. We don't need to use the AC
charger for
around 1/2 the year. In the winter, we charge regularly from the
grid.<br>
<br>
Colorado has a <u>lot</u> more winter sun that SE Ohio. If I did
ours
over again, I'd double the maintainer array. But we have many
periods, of
several days in a row, where it is so dingy that our main array
produces
almost nothing, with no snow cover. I've never seen these
prolonged, low
light conditions in Colorado. If the price difference for a larger
maintainer array isn't too much, I'd likely go bigger, especially
since
your battery bank is twice as big. <br>
<br>
<a name="_MailAutoSig" moz-do-not-send="true"></a>Drake Chamberlin<br>
<i>Athens Electric LLC<br>
OH License 44810<br>
CO License 3773<br>
NABCEP Certified Solar PV <br>
740-448-7328<br>
</i><a href="http://athens-electric.com/" moz-do-not-send="true">http://athens-electric.com/</a>
<br>
<br>
<br>
<br>
At 11:19 PM 10/8/2018, you wrote:<br>
<blockquote type="cite" class="cite" cite="">Lots of questions
this
season..... I'm winterizing a cabin for a customer that will not
be there
for the next 8 months (summer use only). Inverter and loads will
be off.
The rooftop array will probably be covered with snow for
extended periods
of time, and he has a brand new 800 AH set of AGM batteries.
I've
read that AGMs can handle sitting for longer periods of time,
but my
experience is that they are a bit finicky. I'm planning on
adding
a small wall mounted array on a small Morningstar PWM controller
that's
sole purpose is to trickle charge the batteries and off set the
self
discharge in heavy snow. What is the minimum size array
needed?
I've calculated self discharge rates from 2% to 5% /month, and
I'm seeing
a very small array would offset that. Even at 5% monthly
losses,
and 4 hrs of sun/ day, I'm seeing a 10 watt array could meet
that.
My current plan is a pair of 30 watt modules wired in series for
the 24 v
battery. Is that too small? Or should I not even worry,
because
enough sun will creep through the snow to the main array?
Thanks, -- Ray
Walters Remote Solar 303 505-8760
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