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Spudmasher1
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# Posted: 17 Feb 2014 12:41pm
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Help me please! I just got off the phone with a solar company asking about running a 12 volt DC power system for my cabin and they told me it could not be done. I've seen on this site, several people who had what I thought was this same system. 12 volt DC lights, minimal appliances running off of a 12 volt or 6 volt parallel battery bank being charged buy a solar panel. A charge controller and appropriate fuses with two wires running to lights and the ceiling fan. No inverter! Lights would be led.
Someone please help me out and answer my question. Can this be done and how? Thanks in advance. Doug
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bldginsp
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# Posted: 17 Feb 2014 02:36pm
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I don't know much about this but I have heard that DC lighting systems like that are possible but much more expensive to install. Your power is at a far lower voltage, thus far higher amperage. (Volts x amps = watts) therefore, all your wiring and switches, etc. must be rated for the higher amperage, and to use DC current which presents different safety challenges. Most people conclude, so I understand, that it is cheaper to buy an inverter to switch to AC because that makes all the rest of the installation much less expensive, using standard AC wiring and fixtures.
Someone correct me if I'm wrong.
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Steve961
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# Posted: 17 Feb 2014 03:42pm
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I agree with bldginsp that you'd be better off getting an AC inverter. By the time you pay for heavier wiring, non-standard fixtures & outlets, and DC bulbs, you'd be money ahead with an inverter.
The best small sine wave inverter that I can recommend is the 300 Watt Morningstar SureSine. You can find them for a little over $200 if you shop around. If you need something less expensive, Samlex makes a 150 Watt sine wave inverter for a bit over $100.
I have the Morningstar SureSine and am very pleased with its performance.
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old243
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# Posted: 17 Feb 2014 04:20pm
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How many led lights were you planning to have? also the wattages. You also will have diversity, how many might be on at a time , estimated hours per day. If you take watts= volts x amps , you will come up with the amperage load. 14-2 building wire is rated at 15 amps. 12-2 is rated at 20 amps . 10-2 is rated at 30 amps. These are standard building wires available at all hardware stores. If you give more information im sure you will get your answers. Old243
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SE Ohio
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# Posted: 17 Feb 2014 05:05pm
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My 14 x 24' cabin can be lit pretty well by a single 12 v 15 w compact fluorescent bulb. I could have 4 of these and only draw 5 amps. Circuit uses standard 14 ga house wire with a fuse rated at 15 amps.
I'm certainly not running a microwave, but I do run a car stereo and occasionally a 12 volt fan. So at least in my situation, it can be done.
An you tell more about your situation and why they discouraged solar? Heavy shade? 6 months of winter darkness? 
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bldginsp
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# Posted: 17 Feb 2014 05:09pm
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I think Old243 has a point that if all you want is two lights and nothing more, you can use 14-2 or12-2 wire with DC, buy only two light fixtures and one switch, and it will cost less than an inverter. But, then if you want to expand later you are committed to expanding with expensive DC components, or switching over to AC at that time in which case all the money you spent on DC stuff is wasted. But also remember that inverters do not last forever and will eventually need to be replaced. Probably if you buy a smaller inverter and use it near to its capacity you will have a shorter life of the inverter than if you buy one of larger capacity and use it well below its ability, but that's a guess.
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creeky
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# Posted: 17 Feb 2014 05:10pm
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Spud. First look at RV systems. All wired for 12v. I had a travel trailer. With 12v LED lighting. Worked great for the two years I had it. It's not hard to find 12v chargers for your phone/laptop. 12v fans, harder to find and a bit pricey. But a DC microwave? Or a DC fridge that's bigger than a bread box...
If you're wiring for a cottage/cabin you plan on using a fair bit... A good pure sine inverter like the Morningstar uses very little power on idle. And now that you're AC, you can find and use a far greater range of devices. The savings/variety of fixtures/switches/...
IF you get a bigger inverter. Now you can have an electric fridge that doesn't cost the moon. You can have a microwave. TV. Stereo. That fancy propane range that needs AC for the clock/ignition. No worries...
12v is doable and even easy. But with the massive decline in the price of panels and the advent of affordable pure sine inverters. the 12v equation is getting pretty sketchy unless you're staying lights/fan/radio/small rv pump. occasional use.
imho
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Truecabin
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# Posted: 17 Feb 2014 05:48pm
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>>Someone correct me if I'm wrong.
Bldg your wrong
12vdc is easy and low cost if you are mostly using it for lights if you use led lights the wires are tiny. my cabin has great light and my main fuse is 5amps and i only need 2.5amps
thats total bs that you need 12-2 or 14-2 if its to run led lights you can use tiny wires so small they are hard to see. If you put a fuse up front thats small like 5amps its so safe, look at the wire in a 5a fuse its like human hair. but yeah you can use 12-2 or 14-2 or 22 or 24 just fuse it at the source for the wire size you choose
bldg is describing somebody trying to make a 12v system do everything the same as a 120v house does like washer & dryer but maybe thats what you want?
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rayyy
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# Posted: 17 Feb 2014 05:51pm - Edited by: rayyy
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That solar company wants to make money off of you.You know I have been on 12 volt DC for 3 full years now for all my lighting needs.Some 12 volt outlets for my waterpump and cell phone charger and that's it.None of the lightbulbs draws more than 13 watts.I have 6ea) 12 volt light fixtures in the cabin,3 out in the barn.All LED lights from 5 watts to 13 watts.All in 12 guage romex wireing.Your not talking a huge power draw there.I run my generator for all my 110 volt AC stuff like this computer and my T.V.set.all the while that is running it is charging up my battery bank for all the 12 volt stuff.I have been very happy with this set up so" YES IT IS POSSIBLE!"I admit I use propane for my refrigerator,cook stove,hot water and heat but I could use the old kitchen cook stove for all the above(except frig) if I had to.I spend about 20 dollars a week on gasoline for the genny.That is cheaper then the going price of electricity purchased from the grid.I have to laugh when all my co-workers invisions me living like Grizzly Adams but it couldn't be any further from the truth.The only difference,I make my own electricity and use a compost toilet.So I live just as comfortably as any one else!just much cheaper!
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Truecabin
Member
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# Posted: 17 Feb 2014 05:54pm
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agreed it would very expensive to have an electrician wire your 12v canin thats cuz theres no code to follow and he woundnt know what to do to be safe from a lawsuit so he would have to overbuild
i dont know what to tell you if you cant do it yourself your stuck between a rock and a hard place
12v is the lowest cost and easiest but you have to diy
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MtnDon
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# Posted: 17 Feb 2014 06:26pm
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A small 12 VDC only cabin system can be done. It's best kept small and simple, IMO. Like a simple small RV. An old fashioned one without all the modern conveniences.
Wiring it up yourself is only part of the task. Will everyone living with it be happy with the limitations of 12 VDC? As soon as something 120 VAC is wanted that complicates things a little, in that you then have the two very different power systems in one place.
IMO, if the user/builder can not figure out how to build the 12 VDC system themselves they should probably not mess with it. 12 VDC is safer than 120 VAC in some ways, but a short circuit can still melt wires and start fires. As as was mentioned much of the AC equipment like breakers, fuses and switches may not be compatible with safe DC use.
As a note: there is applicable electrical code; the NEC applies to any electrical in a residence (or business of course), including DC. Lots of folks get things wrong when they do low voltage DC systems. #1 error is using black for the negative wire. NEC interpretation is that black can not ever be a neutral which translates to a negative in DC. So, in the USA, a negative in a low voltage DC system should be white as black and red are reserved for 'hot" (+) wires. Canadian electrical code on DC is different.
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