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Simple electric system for off-the grid, solar one day?, grid one day? cabin
Last Post 23 Apr 2011 09:50 PM by jonr. 6 Replies.
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danf26User is Offline
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02 Mar 2011 02:02 PM
Hi all, I'm building a small cabin out here in Western Massachusetts, and Im looking for some advice on setting up the electrical system. The cabin will use straw bales as the walls, so wiring will come up through the foundation (deck on piers), and then be run to a few outlets in the house. We're not planning on hooking up to the grid, but want to wire it so that could always be a possibility. Long term, we would hope to get a solar system hooked up, most likely running on batteries, but possibly grid-fed. Does anyone have recommendations for a simple wiring system that can accommodate the grid, but could easily be converted for solar/battery use? Or, does anyone recommend a book or source that would be useful for someone who's not an electrician (and doesnt want to become one!) but gives the basics for simple wiring. Wish I could be more specific, but thats all I got now. Thanks, Dan
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04 Mar 2011 11:45 AM
Here are some things to think about.

The typical grid-tied inverter matches it's AC output to the grid. Without the grid, there are issues both with creating the output and with the question of where it will go (load). As with backup generators, you have to be disconnected from the grid so that you don't inadvertently harm a lineman working down the street.

Right now, this issue would be challenging for "someone who's not an electrician".

Home Power magazine #137 has an article about inverters that might be a start.
junkhoundUser is Offline
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18 Mar 2011 12:48 PM
small cabin out here

Consider security and DO NOT get any permits:

My son had a cabin 'out here' with no near full time neighbors.

Within 2 years his entire solar, wind, and storage and small diesel generator had been stripped clean by theives.  Seems the theives would keep track of building and electrical permits in the county and a year or so later 'visit' the sites..... One set of crooks even had a GF working for an insurance company appraise them of 'possibilities'
jonrUser is Offline
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18 Mar 2011 09:13 PM
I'd make a 120V AC system with a normal (non grid tie) inverter. I'd use a MPP charge controller between the solar panels and the batteries.



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23 Apr 2011 12:21 PM
There's a good diagram of a basic solar setup at http://mppsolar.com/Grid-tied%20PV%20applications/index.html
(Note: I am not a salesguy for these folks, I just like the diagram as it shows a clear schematic for both the off-grid and grid tied solutions.
I'm currently building an off-grid solution, as we live 2,000 ft from nowhere, and am pondering the same questions as dan.
Dan, for my .02 if I could access the grid for a reasonable cost, that's what I would do.
Junkhound, my brother! (am incorrigible bargain hunter); I hear your son's pain. Our new property has turned out to be located right next door to the area thief. Just spent 600 on a video system. can't wait to nab the sob as the minute I leave the property he comes a shopping. nothing like a neighbor who borrows tools without asking, never tells you he borrowed them, and never returns them.
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23 Apr 2011 02:10 PM
Hey Dan,

I just saw this at an rv site

I would recommend the following, although it is a little difficult without some discussion:

- Magnum inverter - 2000 watts. Most RVers do not need more, and running an inverter way below its peak output is very inefficient. Also, at least look at the Magnum Mini-panel for wiring ease. You likely can not mount the inverter on top, because of space issues, but using the panel makes lots of your wiring very easy. Yes, it costs. But you will be close to its cost by the time you do your own wiring....
- Morningstar Tristar MPPT 60 solar controller
- Sun Electronics 24-volt nominal solar panels. I would use the rebranded and blemed Evergreen panels they sell under their own brand name.
- Trimetric 2025RV battery monitor, or if you like, the Magnum battery monitor (which is integrated, but costs more).
- Midnite Solar combiner with breakers on the roof, Midnite solar "baby" breaker box for in/out cutoff or the solar controller. If not the "baby" breaker box, use an airconditioner 60 amp disconnect box.
- #4 at least (look at the tables) welding wire from the roof to the controller. You may not need as large as #4 with a 24-volt system but I would use at least that,

This looks like the basics
jonrUser is Offline
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23 Apr 2011 09:50 PM
Note that pumps and motors can draw 5x normal loads as they start up. So inverters have to be sized accordingly.
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