[RE-wrenches] Trickle Charging?

[Ray]

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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