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Old 09-09-2015, 12:39 PM
DNZ Male DNZ is offline
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Join Date: Sep 2015
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Default small shed 12volt/dc advice

I have a small shack with a loft that I would like to light it with a 12 volt system. The studs are still exposed so I would like to run wiring before I insulate and panel. I would like some suggestions on an inexpensive solar 12 volt setup with six 5 or 7 watt LED DC lights and the possibility of a converter connected occasionally to the battery for small appliances. Specifically:
what kind and size wire should I run in the walls?
What is the minimum size solar panel should I use?
size and type of battery for storage?
size and type of charge controller?
do I connect the lights to the terminals from the charge controller or should the wiring come off the battery?
Can I use standard household light switches and light fixtures for the 12 volt lights?
BTW: remote, no access to the grid
I appreciate any and all advice.
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Old 09-11-2015, 11:56 AM
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12vman Male 12vman is offline
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Join Date: Oct 2003
Location: Tuscarawas County, Ohio
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First.. Welcome!

Lots to cover but we need more information..

..the possibility of a converter connected occasionally to the battery for small appliances..

What kind of "small" appliance(s)? How long do you plan to operate these appliances in a 24 hr. period? How much power do these things require?

Distance is a big factor when supplying low voltage to an item. How far from the battery is your lighting going to be? Do you plan to have switches locally at the light fixture or somewhere at a distance from the fixture and the power source?

These two factors will help assist you in your design. We need to know how much power you need to design the panels/controller/battery and the lighting situation to decide the wiring needs..

Normal light switches can be used BUT I operate relays to do the actual switching AT the fixture. This concept makes the power wiring shorter to the fixture and adds flexibility to put the wall switch just about anywhere you choose..

I use standard 4 conductor telephone wire to operate the coil of the relay (which is installed AT the light fixture) via a standard wall switch and run the power from the battery directly to the fixture. This make the actual power run as short as possible. This greatly reduces line loss issues and you can put the switch almost anywhere. It's possible to switch a relay on/off at a distance of over 100'. (Saves a lot on wire!)

Fill us in a little..
"Without Deviation from the Norm, Progress is not Possible".
*Frank Zappa*
"Two roads diverged in a wood, and Ió I took the one less traveled by, And that has made all the difference"
*Robert Frost*
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Old 09-23-2015, 10:39 PM
RochBear Male RochBear is offline
Join Date: Apr 2015
Posts: 56
Default The higher the voltage the smaller the wires


All good questions.

Here is my best advice.
1) I would put an inverter in right near the batteries, and then run 110V AC wiring through the building.

The DC wires need to be very large - because the amperage will be high. If you wire things for AC, you simply wire like you would if you were on grid. It also allows you to simply unplug the inverter, and then plug in a generator if you batteries get too low (due to high load, and low solar input)

Also finding AC appliances is much easier than 12 volt DC appliances.

As far as how many batteries, solar panels etc. I have 1200 watts of panels, and they charge 10 deep cycle batteries. This does run a deep freeze and a full sized fridge most of the time. I am going to add two more batteries soon, as I tend to pretty low in the early morning time. (and the charge controller kicks out in the afternoon)
My inverter is a 2000 watt pure sine (4000 watt surge) It works for the ONE circuit in our house. On Sunny afternoons, I often brew coffee, and run computers etc. But when it's cloudy, I end up switching the refrigerator to utility power for over night.

That's my $.02. Don't spend it all in one place.

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