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.
Thanks,
Ray Walters
Remote Solar
303 505-8760
On 10/9/18 8:57 AM, Drake wrote:
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.
Colorado has a _lot_ 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.
Drake Chamberlin
/Athens Electric LLC
OH License 44810
CO License 3773
NABCEP Certified Solar PV
740-448-7328
/http://athens-electric.com/
At 11:19 PM 10/8/2018, you wrote:
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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