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Small Cabin Forum / Off-Grid Living / Need solar panel help
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Fishinbrad
Member
# Posted: 11 Aug 2016 12:05pm
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I have a small hunting cabin that's off grid, and running (barely) on a harbor freight 45 watt kit (please don't flame me, it was free)... I threw out the charge controller and got a Morningstar Sun Saver 6L-12. My battery is a 100ah marine deep cycle. My load is relatively light, consisting of 5 - led lights drawing a total of about 10 watts when they are all on. I don't need a lot of light. We also have a composting toilet with a 12v fan that needs to run constantly at 2.4 watts. My real issue is that the cabin is DEEP in the woods, and I don't want to clear out a bunch of 100' oaks. Before we got the toilet it worked great, but now, every morning the charge controller has gone into LVD and shut everything down until about 11:00 am when the sun hits the panels. It never gets to full charge without me hooking up the generator and charger.

The panels are mounted on the south west facing roof and don't get any good light until about 11:00. With the tree cover however, I do have one other area that gets good morning sun for three to four hours.

My question is this: could I simply add a 100 watt Monocrystalline panel to the area that gets good light and run another charge controller and run both charge controllers into my battery? I understand that this probably isn't ideal, but in my mind it seems that it will work. As I understand, the harbor freight panels simply aren't putting back what the fan and lights are drawing. Thanks in advance.

creeky
Member
# Posted: 11 Aug 2016 03:43pm
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I wonder about your loads:

5 led lights drawing 10 watts when on? Are they very low lumen?

I also wonder at the 2.4w fan draw. that would be .2/ah. Most low/medium quality 12v fans are closer to 1 amp.

How old is that battery? 100ah battery should give you days of use even at the higher draw.

You could turn off the toilet fan at night.

Your solution is good one. imho. And you may need a new battery.

Nate R
Member
# Posted: 11 Aug 2016 04:05pm
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That should be the right draw for the fan. Sun-Mar composting toilets use optional fans to help vent. There's a 1.4w and 2.4w version. I bought the 1.4 to have an active outhouse vent 24/7, and I did verify the power draw.

Fishinbrad
Member
# Posted: 11 Aug 2016 04:19pm - Edited by: Fishinbrad
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The LED draw is correct. They are made from the small strip type led's. A 10 meter strip draws 20 watts, and I used half a roll for my lights. Battery is less than 4 months old. Still under warranty! Nate is correct, I have the 2.4 watt sun-mar. Fan MUST run 24/7, as I don't want any smells!

creeky
Member
# Posted: 11 Aug 2016 05:30pm
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Take the battery in for a check.

2.4x24=60 watts.
10x5(hrs)=50w

per day = 110

100amp hr = 1300w

Something is not right.

Just
Member
# Posted: 11 Aug 2016 05:55pm
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More panel would be the first thing I would try . I have had a similar system for 8 years, amazing what they can do .

timcook
Member
# Posted: 11 Aug 2016 06:55pm - Edited by: timcook
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Id run the 100 watt panel like you have talked about and a bigger charge controler. my set up is a 30 watt and a 15 watt goal zero panels and a colmen 18 watt all tied together to a deep cycle rv batt, i can run my small fridge and watch a movie late at night in bed while charging cell phones and cold beer. so i would start with the panel, also you could tie in 2 deep cycle batt. together you will see a huge diffrance,

MtnDon
Member
# Posted: 11 Aug 2016 08:12pm - Edited by: MtnDon
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Re the SunMar. We have one w/o any fan. Have no smells from the unit. 4" pipe goes straight up about 10, maybe 12 feet

Re pv, yes a 2nd panel and CC can work together.

Fishinbrad
Member
# Posted: 11 Aug 2016 08:33pm
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MtnDon, thanks for the insight! That's good to hear! Man, it's amazing the amount of HELP and ADVISE that is given on this forum! Have been a member over on another "Solar Panel Talk" forum, and all the guidance given over there consists of "you're too dumb to do fifth grade math", or you need a 36v system and 600w worth of panels" to run a phone charger! Many thanks to all, and I'll update this post once I get another panel and controller added.

offgridjunkie
Member
# Posted: 12 Aug 2016 01:19pm
Reply 


If you can, that 100 AMP battery is going to want a little more charge than 100 watts. Buy a grid tie panel (24 volt 200-220 watts) and get a MPPT charge controller and your battery will be happier.

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