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smitty136
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# Posted: 29 Nov 2024 11:47am
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Hi folks,
I have a small cabin in Crawford County, Missouri. I don't have electric or running water. Just a wood stove, rain barrel, and a deep cycle 12 v. battery for two lights and a fan. I'd like to install a solar charger just to keep the battery fully charged to prevent damage to it. I've seen several 10 - 30 watt solar chargers on line for $80.00 and under. My guess is that the charge control devices are the weak link in a cheap system like this. I'd appreciate any advice you can offer. Thanks, Smitty
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Nobadays
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# Posted: 29 Nov 2024 12:13pm
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I've used THIS one for 3 years and it has worked well. The cheap Chinese pwm has charge controllers are a weak link but they are more robust than you would think. If you keep them dry they work quite well for this kind of application.
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smitty136
Member
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# Posted: 29 Nov 2024 01:28pm
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Thank you Nobadays, This is actually the one that I've been looking at.
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gcrank1
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# Posted: 29 Nov 2024 04:06pm - Edited by: gcrank1
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Looks nice 
1st, do you have good southern exposure, no shadows in the proposed array location, especially between 9am and 3pm?
Shadows derate solar meaning you need more panels to get the output needed; and most panels are at best about 70% efficient (that is, if the ad copy says 100w you will be fortunate to really get 70w in ideal conditions).
Dc wiring takes BIG wires so you want the wire run from charge control to battery to be as short as possible. The typical low end panels wiring is only good for about 20' from array to charge control.
Lots of tables for amp dc wiring for x distance online.
Just keep in mind 'shorter is better'.
Fwiw, we have much the same situation as you.
LFP batteries were a huge game changer for us. We have 2x 100ah LFP and swap out as needed and recharge at home. Each has easily 2x the available amp hours as a 100w 'deep cycle' lead acid battery, and about 1/2 the weight. And waayyy more life.
The price of them is pretty reasonable right now; a friend here just sent me a link to the LiTime 100ah on Amazon that is a pretty good battery and a good 'B-Friday' price.
These have worked out so well for us that I didn't even put my solar back up last year.
Be sure to use LED lights.
I have used 12vdc alone, a combo of 12vdc and a small inverter for 120vac and made my smart move to the inverter and only 120vac a couple years ago. Wiring size and fixtures are greatly simplified by doing so.
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smitty136
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# Posted: 29 Nov 2024 06:14pm
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Thanks Gcrank1,
Yes, The slope you see in the picture is due south and stays in the sun for most of the day. This is my first baby step into solar so I have a lot to learn. I only use led lights and the fan is a crappy little tent fan that I plan to upgrade someday.
I would like to have some sort of inverter primarily for charging cell phones. Any suggestions? I don't want to spend a lot on one in case bad guys break in. We just keep the basics in there hidden in two hidie holes. The battery is the most expensive and vulnerable item.
Thanks, Smitty
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ICC
Member
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# Posted: 29 Nov 2024 08:18pm
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Unless you need or want 120 VAC for something else, skip the inverter and buy a USB port that can be connected to the 12 VDC battery.
like this
Wire it, and anything else, with a fuse of the correct size to protect the connecting wires. It comes with 10 amp fuses which is good. If you need a longer wire you may need to go up a size or two to protect against unwanted voltage drop. In that case retaining the same 10 amp fuse is fine.
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gcrank1
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# Posted: 29 Nov 2024 10:13pm
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spencerin
Member
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# Posted: 29 Nov 2024 11:56pm
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Nice place! I'd get grid power there if I could. Is it too cost, and/or regulatory, prohibitive for you?
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smitty136
Member
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# Posted: 30 Nov 2024 08:35am
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Dang gcrank1, They're out of stock on that one, but I'll see what I can find.
Spencerin, Grid power is not an option there. The property is pretty remote and no electric within more than a mile.
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