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Small Cabin Forum / Member's Projects and Photos / My cabin - 12 x 20 with loft
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KC cabin
Member
# Posted: 18 Nov 2010 18:36
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Gotta disagree with MtnDon. The advantage to stainless steel screws is that they resist corrosion (rust) and staining. Stainless steel is an alloy of steel, chromium and nickel and is stronger than steel alone. Well worth a few extra pennies it in my opinion. And Lowes and Home Depot both sell small quantity blister packs of screws.

MtnDon
Member
# Posted: 18 Nov 2010 20:06 - Edited by: MtnDon
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KC, I'll concede that S/S is stronger, but in a normal indoors environment I never think of corrosion as being an issue. Maybe that comes in part from living in a desert. Even our mountains are relatively dry compared to Colorado and the PNW. I do use S/S outdoors a lot myself.

I meant to ask a question when the subject of gluing came up. Are the stringers finished with some clear finish? If so, at the very least you should sand and/or scrape the finish where the cleat will be fitted.

I like Lowe's and HD, even defend them against people who say they sell trash, but I cherish the better selection at the Ace and True Value near me. I can always buy one of anything instead of multiples I don't need. Plus the TV owner lives on my street and runs a great shop. (Where else could I buy a snow shovel, in the desert, in summer?)

GREATROSE77
Member
# Posted: 21 Nov 2010 21:55
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NICE! How is the solar panels working out for you. I mean longterm maintanance? I have considered it but not sure how well they last without problems.

MtnDon
Member
# Posted: 22 Nov 2010 13:43
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There is no maintenance. If we're there and it snows I might sweep the snow (extended handle floor broom) off if the sun comes out. There are trees behind their sun facing location and a bad storm could make a tree fall but that's a long shot. There's always the possibility of some idiot with a gun taking a potshot at them, but hopefully it's isolated enough that won't happen.

We leave the system to run itself mainly. I add water maybe twice a year to the batteries. When we are absent the panels continue to feed the charge controller and keep the batteries up to full. If we are planning on being absent for more than a couple of weeks I cut the absorb charge time down as it is not necessary and may cause excessive water use over the winter.

We leave the cabin power (DC and inverter AC) turned off; the inverter power connection to the batteries is pulled.

Canadian girl
# Posted: 31 Jan 2011 08:49
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I love your cabin . My husband and I recently bought land with a 12 x 20 cement pad and were looking for ideas to build a family cottage . Your design has certainly inspired us . Do you have pics of the cabin with the deck installed ? We were thinking we would like to put a covered deck on as well to maximize the living space. Perhaps even screen it in as mosquitoes seem to be a problem with outdoor summer living . thanks for posting your pics :)

guest
# Posted: 31 Jan 2011 18:18
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Quoting: MtnDon
There is no maintenance. If we're there and it snows I might sweep the snow (extended handle floor broom) off if the sun comes out. There are trees behind their sun facing location and a bad storm could make a tree fall but that's a long shot. There's always the possibility of some idiot with a gun taking a potshot at them, but hopefully it's isolated enough that won't happen.

We leave the system to run itself mainly. I add water maybe twice a year to the batteries. When we are absent the panels continue to feed the charge controller and keep the batteries up to full. If we are planning on being absent for more than a couple of weeks I cut the absorb charge time down as it is not necessary and may cause excessive water use over the winter.

We leave the cabin power (DC and inverter AC) turned off; the inverter power connection to the batteries is pulled.


guest
# Posted: 31 Jan 2011 18:19
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LOL @mtndon

edwin999
Member
# Posted: 2 Feb 2011 07:39
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good forum.I am happy to return in this forum again.

p0rtia
Member
# Posted: 27 Mar 2011 12:56
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Hi Greatrose -- thanks. :-) The solar has worked out great. I'm thinking of adding a third 100 watt panel this year (we don't get a lot of sun), and so far the only wear and tear I've seen has been on my inverter (the fan seems to have a loose bearing--I called the manufacturer, and they said, yeah, run it till it dies and then replace it, cause it's not cost-effective to fix it). This will be the fourth year (I think) for the golf cart batteries--I'll be interested to see if they will still charge okay. I've treated them with kid gloves--except that they live in an unheated shed all winter. I set up my solar by myself, on a budget, and so far so good. I worry about grounding. The panels are grounded, and I've used the ground screw on the Inverter, but I'm still waiting for somebody to tell me if I have to ground the batteries, and if so how to do it. Always an adventure.

p0rtia
Member
# Posted: 27 Mar 2011 13:00
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Hey KC Cabin! Spring is coming, and in six weeks I'll be back up at my cabin for Year II. :-) This year, interior paneling, chimney, and hopefully the ram pump I've had waiting to be installed for four years! I want to get an awning for the deck, too. I've decided against a wooden porch roof because of cost and also the fact that the cabin is on skids, so I don't think structurally it's a good idea.

Wanted to mention that the last thing I did before I left in December was to put the cleats under the stairs (glue and screws--can't remember which kind LOL). I'm hoping they'll be nice and snug when I get there in May. Thanks again for all the help.

bobrok
Member
# Posted: 27 Mar 2011 15:45
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Quoting: p0rtia
inverter (the fan seems to have a loose bearing--I called the manufacturer, and they said, yeah, run it till it dies and then replace it, cause it's not cost-effective to fix it).


Hi p0rtia,

I'm not sure what type on inverter you are running, but I'd venture the cooling fan is a pretty comparable item from one to the other, unless you perhaps have a high-end model inverter.

I bought a dc brushless motor 12v fan for $12 at Radio Shack. I thought this was outrageous but it was cheaper than a new inverter.

A few quick solder connections and maybe some retrofit to the mounting pins and you're good to go.

Hey if you can build a cabin you can fix your inverter...:-)

p0rtia
Member
# Posted: 27 Mar 2011 16:06 - Edited by: p0rtia
Reply 


Hi bobrok -- LOL I asked the very nice fellow from Xantrex about that. He sort of said what you said...only with less optimism. :-) I am a total dunce when it comes to anything electric (which makes my solar system and that fact that nothing has blown up yet a miracle). I sort of thought of giving it to a friend who does small engine repair. Except that his version of helping out is to eagerly take your semi-functional small appliance (last time it was a generator), put it in the back of his shop, and forget about it. Okay, I'm game. A brushless motor isn't the same thing as a fan, is it? Help me out here. I bet you're gonna tell me they come together. It's an Xantrex Xpower (this one: http://www.amazon.com/XPower-1000-Watt-Power-Inverter/dp/B0002ZA9RC). Now....soldering you say. Yes, well, I purchased something I thought was a soldering iron last summer, and tried to solder some wires onto some MC4 connectors (see, I'm game). It was kind of a disaster. But I'm sure I'll improve with experience. Silver solder, right? And uh...they don't use flux any more, right? It's getting the wire to temp that seems to be my problem. So I'm all ears. ;-)

bobrok
Member
# Posted: 27 Mar 2011 18:40
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There's usually 4 long screws that hold the whole inverter together. Back these out, remove the cover and locate the fan at the rear of your unit. Your fan probably looks something like the one in this photo. These things are cheaply made and blades break off and constant use just basically gums up the works.
Any electrical/electronic supply wholesaler near you probably sells these. I didn't even solder my connections (2 wires) but used crimp connectors instead. Be sure you mount the fan so that it is exhausting the air, not blowing into the unit.

You know, on second thought, if you take the unit apart and go to the shop I am quite sure they would give you a good explanation and match up something for you. These fans operate on miniscule but different voltages and you might feel more comfortable doing it this way the first time and then you will be an expert the next time it happens. You should keep a spare inverter at any rate in case of problems (I had two just burn right up on me right out of the box!) if you rely on them for your power.
fan
fan


p0rtia
Member
# Posted: 27 Mar 2011 19:33
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Thanks, bobrok! Hey--that kind of fan? I know about those. :-) I will give it a try. I picked up a spare inverter that will to do trick for a while (it pulls about 50 percent more amps than the Xpower, so I don't want to just switch it out permanently). And yes, the nice Xantrex guy said either a loose/missing bearing or a broken blade. And I can use crimp connectors (and wire nuts) just fine. Many, many thanks. And now I must wait six more weeks till I head north and give it a try. :-)

bobrok
Member
# Posted: 27 Mar 2011 20:01
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You're welcome

Quoting: p0rtia
And now I must wait six more weeks till I head north and give it a try. :-)


OK, well that takes the air out of what was to be my follow up question on the snow cover in the ADKs.

DYING to get back up there.

p0rtia
Member
# Posted: 27 Mar 2011 20:14
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The report is that the snow was gone last week, then another six inches and now it's miserable again. My neighbors are going stir crazy. Must mention that one of them got worried about my sweet new cabin when the snow got more than two feet deep in January, went in, and racked the snow off the roof--now that's a good neighbors.

I'm right on the Vermont border, over the mountain from Manchester VT, btw. Not so much ADK. Where's you?

Me? I'm in Florida, wearing shorts and thinking about tomorrow's tennis match. :-)

Quoting: bobrok
Quoting: p0rtia
And now I must wait six more weeks till I head north and give it a try. :-)


OK, well that takes the air out of what was to be my follow up question on the snow cover in the ADKs.

DYING to get back up there.


bobrok
Member
# Posted: 27 Mar 2011 20:30
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Nice neighbors, the kind you want to have!
Our place is in the central ADKs at Blue Mountain Lake. We live in WNY near Ra-cha-cha.
I was going to apologize for butting into the thread, but then I realized, hey it's your thread!
Not feeling so guilty now.
Quoting: p0rtia
I'm in Florida

Jealous, yes, guilty not so much. Enjoy!

p0rtia
Member
# Posted: 27 Mar 2011 20:50
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Not so far away. Sure is a beautiful area--quite wild, I think. We're pretty tame in my neck of the woods. Take care!

MtnDon
Member
# Posted: 28 Mar 2011 14:10 - Edited by: MtnDon
Reply 


Quoting: p0rtia
I've treated them with kid gloves--except that they live in an unheated shed all winter.


Batteries like cold better than they like heat, as long as they are kept charged and do not freeze. If frozen, they are usually good only for the core charge when buying new ones. I should add their life is increased in cooler temperatures, but their capacity is reduced, so with batteries in cold places you might need more of them to supply all your power needs.

Do you leave them to winter with the charge controller and panels keeping their charge up?

Quoting: p0rtia
I worry about grounding. The panels are grounded, and I've used the ground screw on the Inverter, but I'm still waiting for somebody to tell me if I have to ground the batteries, and if so how to do it.


Grounding is a part of the system that can get confusing. Are the panels, charge controller, batteries etc fairly close together; like 50 feet or less? If so The DC side of your system should have two 8 foot copper clad ground rods driven into the ground fully. They should be connected with copper wire. One rod should then be connected to a ground buss bar, a piece of copper that all the DC grounds will connect to.

If there are more than one PV module, each module frame should be connected the others in such a manner that any one module could be removed from the system if necessary, without disturbing the ground connection of any of the other modules. The module ground should also be grounded to any metal supports, poles or roofing if on a metal roof. Then one copper ground wire from the array is connected to the ground buss bar. The grounding lug on the charge controller should be connected to the ground buss. Ditto for the inverter. One ground wire should be connected from the batteries negative to the ground buss bar.

There should also be a DC lightning arrestor. This connects across the positive and negative wires at or near the modules. Some combiner boxes have space for an arrestor. The third wire from the arrestor connects to the ground buss bar. If the array is struck by lightning the arrestor shunts the lightning strike to the ground rod before the charge controller or other equipment is damaged.

Grounding on the AC side of the system is carried out in the same manner as a house connected to the power grid. The AC system should have its own ground rod(s). It is always better to have two ground rods with each connected to the other.

Warning: If there is a generator in the system it may or may not need special grounding. Always follow manufacturers recommendations for best results.

If that is confusing make a diagram of all the equipment and how all your positive and negative connections are made and I can try to help.

p0rtia
Member
# Posted: 28 Mar 2011 14:24
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Thanks, MtnDon, I will through together a diagram and post it shortly. If you can indicate where to wire the ground rods, that would be great.

Quoting: MtnDon
Do you leave them to winter with the charge controller and panels keeping their charge up?


There no one around to monitor the system in the winter, so I stow the panels in the little shed I have on the hill, and I take the batts down to the house on the property, where they are stored on wood in a garage. My tenent charges them in the fall, once in mid-winter, and again in the spring before I return. So far he hasn't had any problems.

Quoting: MtnDon
If that is confusing make a diagram of all the equipment and how all your positive and negative connections are made and I can try to help.


MtnDon
Member
# Posted: 28 Mar 2011 14:55
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Quoting: p0rtia
There no one around to monitor the system in the winter


A good reliable system should have no problem wintering over and keeping itself up. I have a couple winters on our cabin system and something like a dozen of the RV system. Both come through the winter perfectly. Better than having to move 800 lbs of batteries twice a year, plus when we snow shoe up to the cabin we still have the use of all the lights and appliances.

p0rtia
Member
# Posted: 28 Mar 2011 15:23 - Edited by: p0rtia
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Quoting: MtnDon
If that is confusing make a diagram of all the equipment and how all your positive and negative connections are made and I can try to help.


Okay, here (somewhere) is a rough diagram. I can't remember how many amps the ANL fuse is. Maybe 80?

There is no grounding lug on the charge controller.

My goals for 2011:

- Add a third 100 W panel
- Add disconnect switch. Question is, where? What kind?
- Add AC breaker at cabin
- Find out if I need more fuses, and if the fuses I have are okay.
- Ditto grounds
- Add DC breaker box instead of combiner box?

Grateful for any and all input.
Solar_diagram.jpg
Solar_diagram.jpg


MtnDon
Member
# Posted: 28 Mar 2011 19:40 - Edited by: MtnDon
Reply 


I assume a couple things. The PV modules are connected in parallel. Their Voc is about 17-18volts and their Isc is about 6 amps.

The wires drawn in black in my drawing are what you already have, if I interpreted your sketch correctly. Nothing is to scale. The objects and wires in red are what should be added, in my opinion.

+ one ground rod, connected to the existing rod.

+ the Circle with the red A inside it is the lightning arrestor.

+ the red rectabgle at the combiner box is a ground buss, a convenient thing to connect all grounds to. The idea is to make it possible to remove something without disturbing the ground of anything else.

+ ground wire from the ground buss at the array/combiner to the charge controller area

+ ground buss at the charge controller/battery/inverter area

+ ground wire from charge controller to the ground buss

+ ground wire from negative battery to the ground buss

+ ground wire from inverter ground lug to the ground buss

+ Circuit breakers:
CB0, CB1 = sized to protect the output of the PV array. Sometimes it is handy to have one at each end of that run. If only using one use one at/near the panels/combiner. With PV modules in parallel that adds up the panel Isc rating. If that was 6 amps = 12 amps total. Select a breaker 1.56 X that. (1.56x12 = 18.72, use a 20 amp) The voltage rating of the circuit breaker should be the Voc (17-18?) times 1.56. (17.5 x 1.56 = 27.3. Using abreaker rated higher than that is fine. If you are planning to add one more module in parallel size that breaker for the new power rating. CB#0 should be in the enclosure... I didn't have room in my sketch.

CB2 = sized to protect the max amps output of the charge controller. Same rules for multiplying by 1.56 to select rating.

CB3 = sized to protect the inverter; use inverter mfg recommendation for the amps and 1.56 x 12 volts = 18.72 or greater for the volts.

A good breaker can be used as a disconnect switch. Breakers must be rated for DC applications. Regular household AC breakers generally are not rated for DC power. It is fine if the voltage rating is way higher than needed... like a 125 volt rating for a 27 volt need. Breakers must be mounted vertically unless otherwise marked.

Combiner boxes like Outback and Midnight have breakers available for them.

A good source for DC rated fuses and breakers is solarseller.com Prices are usually good. Their breakers may not fit other boxes. I have used them mounted to a plywood backing board in an enclosure.

Breakers and fuses should not be mounted in a battery compartment. Neither should any equipment like charge controllers or inverters be mounted above batteries.

If you want a disconnect in the DC side anywhere in place of a breaker, those black one with red handles that can be bought at auto or RV suppliers work, but they are not UL approved so if you are inspected they won't pass.

AC breaker at cabin? If the inverter has a breaker protecting the built in receptacles, not really needed. But okay to use any standard home breaker box.

Hope this helps.

p0rtia
Member
# Posted: 29 Mar 2011 07:05
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Quoting: MtnDon
The wires drawn in black in my drawing are what you already have, if I interpreted your sketch correctly. Nothing is to scale. The objects and wires in red are what should be added, in my opinion.


Much appreciated -- think you forgot to upload the diagram? :-)

MtnDon
Member
# Posted: 29 Mar 2011 10:17
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oops
schematic
schematic


p0rtia
Member
# Posted: 29 Mar 2011 18:03
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Thanks, MtnDon. Will come back with questions in a bit.

Erins#1Mom
# Posted: 29 Mar 2011 19:45
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pOrtia,
In my wondering through the site, I found your first postings and cabin one of my favorite. I have now saved app. $1000.00 cash to start my cabin. I would love to see your cabin plan and possibly borrow if possible. Do you have new photos of the inside?

p0rtia
Member
# Posted: 30 Mar 2011 07:32
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Erins#1Mom

Hi Erin2#1Mom -- Thanks. I drew a rough plan (meaning, to scale, but not including construction methods) on graph paper, and the don't include the foundation (such as it is). Also, the height of the flared roof over the loft was altered on the fly by the builder. I don't have those drawings with me now, or any new photos. In May, I will, if you want to keep in touch or email me.

p0rtia
Member
# Posted: 2 Apr 2011 08:24
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Hi MtnDon. Here are my questions about your schematic (for which many thanks:

1- As I said, there is no ground lug on the charge controller. And "in the area of the charge controller" is too vague for my "ground state of ignorance." ;-) So are you suggesting I like solder a ground wire onto some part of the metal housing of the charge controller? Or maybe use a tap screw and hope it doesn't hit anything important inside?

2- You say CB-0 should be "in the enclosure". I don't know what enclsosure you mean -- in the combiner box?

3- Okay, I know what vertical means, but I don't understand why circuit breakers have to be mounted vertically. Do you mean if I use a breaker box, the cartridge-type breakers have to be vertical? Do the little fuse block types (these: http://www.solarseller.com/dc_circuit_breaker_breakers_rated_up_to_80_volts.htm) have to be vertical?

Many thanks for the link to solarseller.com. I have been totally confused by the discussion of circuit breakers for years (picturing the [expensive, to me] box type breaker box with those sort of cartridge removable breakers), and was gratified to see the little what I call block fuses, aut-style breakers there. :-). In fact, I have those little 20 amp 12 volt breakers in my system, one protecting each panel. I will add one of the proper amperage between the charge controller and the batts. Likewise, I have an ANL fuse (that's what they call it -- supposed to be Class-T?) between the batts and the inverter, of the amperage recommended by Xantrex. Such is my shoe-string solar system! Perhaps next year I will invest in a more professional (more highly priced) combiner box. I add what I can afford each year.

Cool about the RV-type disconnect switch. I had seen those and wondered if I could use them. :-)

Again, many, many thanks. Lots of good info--gives me good direction on what's okay and what needs an upgrade. Cheers!

MtnDon
Member
# Posted: 2 Apr 2011 10:16
Reply 


1. No provided ground lug. Oh. That's a good question and I don't have a real good answer as an NEC approved unit would have a ground lug. At most I'd use a ground wire with a connector under a mounting screw if the case is metal. If plastic case I'd probably forget about it.

2. within the combiner bix just to keep curious fingers and accidental tool contact away from the terminals.

3. breakers mounted vertical, refers to panel mount type breakers, ones with switch like levers or handles, as in a home breaker panel. Vertical as in when the breaker is on the handle is up. That's because they produce an internal arc when tripped by excess current. The arc always moves up, as in warm/hot rises. If one of those breakers was mounted flat on it's back they may cause problems.

The small up to 80 volt series do not have any orientation limits that I know of. One thing I like about using the lever handle typw of breakers over those though, is the lever/handle type can be used as a disconnect very easily. Not sure if those others can.

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