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Small Cabin Forum / Off-Grid Living / Off-grid power for cabin (like an RV system)
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Brian
# Posted: 21 Feb 2008 12:15
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An article I read years ago, in Pobular Mechanics (I think), suggested powering the cabing from your vehicle. install an additional battery in your truck, and set it up like an RV system - charge both when driving, but only drain one for the cabin. When you pull up to the cabin, "plug it in" to your truck. There are 12 v lights and appliances available in the RV stores.

Vince P
Member
# Posted: 22 Mar 2008 17:58
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Hi Brian,

I have actually done something very similar, and while this sounds good in theory, there are some caveats.

1. You will need to be able to access your cabin with your vehicle, which I can do, except for about 4-5 months of deep snow. In which case I sled everything in, including a battery... until now (more on that later).

2. When you charge the battery by driving and it is not the sealed type, it will need to be done outside the vehicle, otherwise you will be generating hydrogen gas, which is poisonous, not to mention explosive.

3. 12V lights and such and are very expensive compared to standard household lights and appliances.

4. The wiring from your vehicle to the cabin needs to be short otherwise; the 12v system loses a lot of power through long wiring. Better to use an inverter to minimize the loss and be able to use regular household lighting and appliances.


I just finished a solar system at my cabin 2 weeks ago and no longer need to deal with any of this. The total expenditure was less than $350 and relatively easy to install once you understand how it all goes together.

- 2 solar panels (15 watt amorphous type) $80 ea. on sale from norther tool x2 =$160

- 1 charge controller from northerntool.com $27

- A deep cycle marine battery (118 amp hours) from AutoZone $80

- 400 amp inverter from Home Depot $40

- Wiring, outlets, compact fluorescent bulbs, misc electrical supplies $40

unixfmike
Member
# Posted: 21 Aug 2008 01:29 - Edited by: unixfmike
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What can you actually power from this? I'm currently looking at solar systems under $1,000US and would like to know what your particular 30 watt system powers. Ultimately my goal is to provide power for the following :

3 lamps/light fixtures (bedroom,bathroom,kitchen/livingroom)
1 mini fridge 3-4cu. ft.(continuous normally 2 days on, occasionally 1 week on)
1 21" tv
1 dvd player
1 cell phone charger

I've been able to find a few people using different solar set ups, but have not been able to find out what their systems actually power.

Mikew

CabinBuilder
Admin
# Posted: 21 Aug 2008 09:43 - Edited by: CabinBuilder
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Quoting: unixfmike
What can you actually power from this?


Check this power consumption chart (at the bottom of that page) - it should give you an idea.

Vince P
Member
# Posted: 21 Aug 2008 10:21 - Edited by: Vince P
Reply 


Quoting: unixfmike
What can you actually power from this? I'm currently looking at solar systems under $1,000US and would like to know what your particular 30 watt system powers. Ultimately my goal is to provide power for the following :

Real world usage for a family of five, to power 4 compact flourescent bulbs (1=23Watt, 3=9Watt), 2 led nightlights, run the kids portable dvd player, 1 digital alarm clock and cabin alarm system (only uses power when triggered) is approximately four days on a fully charged battery. The lights are turned off when not in use and ocassionaly we plug in other entertaiment devices, such as a radio or kids video game charger.
The 30 watt panels are for charging the battery. The battery itself is what determines capacity and in this case my 118 amp hour battery for $80 was the most cost effective I could find (time will tell how durable it is). I'm planning to hook up another identical battery in parallel to double the capacity. Ideally, I'd like to have three batteries and a few more panels, but this suffices for now. For now when we are there for an extended time and we run the battery down, we go back to basics and use candles, oil lamps, an aladdin lamp and even a propane lantern. The battery can also be recharged with a generator and battery charger as another option.

Be careful powering a fridge, I have a mini fridge that I tried powering and it sucked the battery dry in less than a day. Now we use a huge cooler that keeps ice for about 4-5 days in the summer. If you are set on a fridge, look into propane. anything from full size to mini ones that go in RV's are available.
Battery/inverter setup
Battery/inverter setup
2 15W solar panels
2 15W solar panels


littlesalmon4
# Posted: 21 Aug 2008 19:33
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there are 12 volt refridgerators available.
Their problem is cost.
You can do a search on Sundanzer fridges and freezers.
Oh ya the cost is you better sit down
between 1000 and 1200

littlesalmon4
# Posted: 21 Aug 2008 19:38
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You can also try partsonsale.com
This place is called solatron technologies.
They have everything wind and solar for power generation.
They also sell 12 volt fridges and freezers.
They are located in California. Shipping is not to bad.
200 to ship a fridge to the Yukon.

p0rtia
Member
# Posted: 4 Sep 2008 17:49
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Hi all. I recently "finished" installing a 100 watt panel, 20 amp charge controller (the one someone mentioned here :-)), four golf batts, 1000 W Xantrex inverter. Cost about 1K$, including running cable and conduit 150 feet from the nearest south-facing slope to my little hideaway in the woods. I'm very happy, as it powers my computer (work), a fan, and the occasional small appliance with no problem. Thanks to all here. :-)

I'm a total novice (except I've done a lot of wiring), so it was a challenge. I'm wondering if there are any solar geniuses out there that can answer a couple of questions I still haven't answered. For example, can I just walk away for a couple of weeks and not do anything more
drastic than turn off the inverter and stow my connector cord? Should I maybe cover the panel? I've been detaching it for fear something would overload (I've read and almost understood how the charge controller prevents that), but that's a drag (literally). Anybody? Thanks!

CabinBuilder
Admin
# Posted: 4 Sep 2008 18:18 - Edited by: CabinBuilder
Reply 


Congratulations with finishing the solar system for you cabin - a decent setup (comparing to mine at least).

Quoting: p0rtia
...can I just walk away for a couple of weeks and not do anything more drastic than turn off the inverter and stow my connector cord? Should I maybe cover the panel? I've been detaching it for fear something would overload...


You should keep inverter turned off when you are not using it (i.e. when you don't need 110V for appliances) - it drains energy even when idle and no appliances are connected.

Keep solar panel, charge controller and battery always connected - this will keep system always charged and ready. The purpose of controller is to maintain this and it will not overload the battery (unless it is faulty or something).

swanugly
Member
# Posted: 4 Sep 2008 23:15
Reply 


how much cold will a battery withstand ? were our cabin is the temperature goes down to -35 , without attention i guess it would freeze ? is there a way to protect it or do i have to bring it home every time i go ?

CabinBuilder
Admin
# Posted: 5 Sep 2008 09:08
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I have read somewhere that lead-acid battery will withstand freezing temperature if it remains fully charged (i.e. hooked up to the solar panel/charger).
Think of it as a car battery during winter and freezing temperatures - it performs well if car is periodically driven and battery is kept charged.

I leave my solar setup up for the winter season. I've had couple winders of -20...-30 C or lover - OK so far.

I just unplug the the output plug when I leave, so if there is a water leak, tree falls or something else there are less chances of a short circuit.
If you take battery home for the winter you still should keep it fully charged - my manual tells me to plug it into the trickle-charger every few weeks or so, even if it is at room temperature.

p0rtia
Member
# Posted: 5 Sep 2008 12:51
Reply 


Hey, thanks for your reply, Cabin Builder. :-) That's a relief to know, as I worried about the cumulative effect of slightly twisting the wires if I touch the set up so often. I will take the system in for the winter, though, as I am not here for five months, and there is no upside to leaving it, well...up. Batts to go in my neighbors shed where he can trickle charge them once in a while.

My other big issue: grounding. There is no way I could sink a grounding rod six or seven feet in the ledgey (cf. sunny) spot where the panel is. My Home Depot guy told me to dig a trench a couple feet deep, bend the rod into an L, bury the six or seven feet and prey. Which I did. But I haven't researched this on the net, and am worried I didn't bury it deep enough, and that the soil is too gravelling and loose. I grounded the panel, and I've also grounded the Xantrax 1000, despite the fact that the Xantrax people told me I didn't need to (only if I hooked up the inverter to a car batt). My question is, how the bleep to I tell it is actually grounded? I bought a portable gfci plug (Home Depot adivse again), and it doesn't work at all, which indicates to me that my 110 coming off the inverter is not grounded. I'd appreciate any advice anyone has.

On a happier note, I just finished (except for rain protection) setting up one of those portable "briefcase" style solar panels (13 W) to keep a 12 v batt I've got powering my wireless repeater in a glade in the middle of the woods. The repeater draws minimual (.4) amps, so I'm pretty sure this will work if I can get enough sun on the panel. Great buy on ebay -- 54 bucks, with blocking diode. This enables me to actually work when I'm here (including right now!), and as I'm self-employed...hey. It's heaven!

swanugly
Member
# Posted: 6 Sep 2008 01:36
Reply 


Quoting: CabinBuilder

I have read somewhere that lead-acid battery will withstand freezing temperature if it remains fully charged (i.e. hooked up to the solar panel/charger).
Think of it as a car battery during winter and freezing temperatures - it performs well if car is periodically driven and battery is kept charged.

I leave my solar setup up for the winter season. I've had couple winders of -20...-30 C or lover - OK so far.

I just unplug the the output plug when I leave, so if there is a water leak, tree falls or something else there are less chances of a short circuit.
If you take battery home for the winter you still should keep it fully charged - my manual tells me to plug it into the trickle-charger every few weeks



that make sence to me , thanks

Wolfer
Member
# Posted: 23 Oct 2008 00:08
Reply 


Portia,

One of these guys can tell ya how to read an ohm meter. Way back When I used to run a portable crushing plant grounding was always an issue. Here is what we did . Since our Plant had a screen deck On it we would take and old screen and sink it down about 12 inches or so and cover the entire screen with about 2 inches of rocksalt and wet it down real well then barry it. Theory behind it was the Salt helps conduct Better there for giving you a better ground. Dont know all the technical terms But we started doin it after a failed MSHA inspection On our ground and Never had another when we went to this style of ground

upnorth
# Posted: 29 Oct 2008 16:31
Reply 


I have been leaving my batteries outside in my battery box, hooked to the charger controller and panels from November to April. We are in northern Minnesota(70 miles from the Canadian border) Temp gets down to -40 from time to time. You guys are correct, batteries will not freeze if they are kept full. We have even used our cabin in the middle of January and had no problems with the power.

Vince P
Member
# Posted: 19 Nov 2008 11:27
Reply 


For a similar inexpensive system similar to the one I posted above, see this article:
http://www.otherpower.com/wardsolar.html

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