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Solar noob seeks advice, offgrid two months now.  RSS feed

 
Dustin Nemos
Posts: 95
Location: Central TN
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Hey everyone! Cabin in the woods here and loving it, but still very unfinished and just ordered my solar setup.

Going off the advice from backwoods solar catalog I bought a 24v system with around 800 watts and 8 batteries, I'm learning about every facet as I go. My run to a well let area ( in shaded forest) is about 100 feet or so, I have very little space but I plan on doing a tight plywood box with a little breathing room in it for airflow and a pipe out the top to a short run outside, possibly with a tiny fan ( I saw a starry hilder battery box video on YouTube I liked) they had the fan neatly done in a pvc pipe. I'd love advice on recreating something like that and how to run it D.C. (And the lights) while leaving other stuff on ac.

Also I have a sams club chest freezer as well as a small mini fridge but they are not the nice solar efficient kind and I wondered if I could superinsulate or in some way improve efficiency to where I could run them with my smallish system.

I also want to be safe I saw a Tin hat ranch video explaining solar systems but mine is a bit bigger, I like how he suggested putting manual disconnects in on every point in addition to the fuses I think my system only comes with fuses.

I did order a trimetric meter and well reviewed go power 3000 watt inverter and I hope to make my setup scalable as needed up to that point. I'm fairly conservative with power use and will be heating with wood but I also use a lot of Internet for learning and staying plugged in.

Been fiddling with a signal booster and barely have a little signal off cricket with my harbor freight 45 watt setup we currently are using.

I'm sure I'm missing things but I'll have more questions as we go. My wife and I have been hauling things uphill for the last two months and are living in an 8 x 16 cabin we still need to side and upgrade the roof on. Any advice greatly appreciated we made the jump but found we really have no idea yet how to do some of these things!
 
Dustin Nemos
Posts: 95
Location: Central TN
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Been trying to get all my parts together as well and have come across some parts for clamping solar panels to unistrut and I do not understand the seen wmc grounding clip part, any advice or links to diy guides here? Or how to attach grounding wire to the various metal parts I don't understand how those lugs work, or any of the little pieces that would hold the wires to plywood if I create a power center to help organize
 
frank li
Posts: 193
Location: Michigan
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Dustin, what charge controller and what solar panels did you buy?
The reason i ask is, you will want to know what the maximum voc, or open circuit voltage that is acceptable to the control and what the voc of your panels are.

These specs set the home run circuit confines for getting the power to the battery from the 100' distant location of your solar access or clearing in the trees and will help establish an appropriate wire size.

100' is not generally a problem, especially in a 24 volt system and even better if you can wire panels in series to get up around 60 or 75 volts open circuit or higher. 75v is common as a max in pwm controls and some can accept higher, even without mppt.

Either way, max voc of the control and panels are critical specs.

I would look at breakers from midnite solar and a "big baby box" enclosure for them inside the building or other weather proof area, if you want cost effective disconnects. Its like a micro mains panel in a regular home. For a disconnect at the array, a dc rated, outdoor type from an electric store can work, overcurrent protected by a fuse or breaker at one end or the other.

As a micro system option, i like blue sea, marine fuse/distribution blocks, but using certain midnite devices, you can have ac and dc breakers (disconnect and overcurrent in one switch) in a single enclosure.

https://www.altestore.com/store/enclosures-electrical-safety/electrical-enclosures/disconnectload-enclosures/dc/midnite-solar-mndc125-mini-125-amp-dc-disconnect-p2414/

https://www.altestore.com/store/enclosures-electrical-safety/electrical-enclosures/disconnectload-enclosures/ac-andor-dc/midnite-solar-big-baby-box-for-ac-or-dc-breakers-p7475/

https://www.altestore.com/store/enclosures-electrical-safety/electrical-enclosures/combiner-pass-through-boxes/midnite-solar-mnpv6-combiner-box-p4566/

http://www.google.com/shopping/product/11194550482139301264?lsf=seller:2709845,store:16153724112987860968&prds=oid:1971996560605440942&q=blue+sea+fuse+distribution&hl=en&ei=jNVkWaaNHKqkjwTJlonQCQ&lsft=gclid:CJDxm-StgdUCFQgQaQodx8YDyg

The refrigeration... yes, insulate it heavily on any sides it does not use as ventilation or heat exchange and you can put it on a timer so it does not run at night, or simply turn off your inverter at night if you do not need ac power.

All of your dc powered lights and devices should have dc rated switches and overcurrent protection appropriate to wire size.

Buy high quality dc led lights for camper, boat and rv replacement or preferrably ul/etl/etc., Listed lighting.

A client of ours had a meltdown in an rv fixture made of plastic (fuel) of a cheap paddle type rv retrofit led! The led was only 4 watt, but it died hot anyway and on a 2 amp fused circuit.

Buy good quality and use discretion in arrangement, even in a cabin in the woods.

The community here will be of help as you move down the off grid path, im sure. If younsend a photo of your parts for mounting, ill help puszle it together, but manufacturer manuals on installation are the propper source.

Unirac is easy to work with and its basically an erector set, so...





 
frank li
Posts: 193
Location: Michigan
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More information on how you use your inverter will help. Some inverters can soak a battery just being on for a few days of cloudy weather. Sometimes a big inverter is used just for big jobs and a smaller inverter for general use in standby 24/7

Standby watts or watts in search mode, if the inverter has it. This will tell you what to expect. A low standby wattage of 3w-12w is a good target for cabin power.... hard to find on the cheap.

Then i looked at your inverter specs.... 9w in powersave mode. Not bad for a 3kw box thats not an outback!
So it comes to keeping it in search or powersave mode, or off if or when you cant afford watts. May not even be an issue, but when in standby it will consume 38.4w with no load!

This means the inverter can consume about 1.5 peak sun hours of your array output, to keep it on for 24 hours.... 3 or 5 cloudy days and depending on battery size, it gets dark and the fridge gets warm, and no entertainment or communications.

How many total amp hours is your battery?
 
Joshua Parke
Posts: 108
Location: Northern New Mexico, Latitude:35 degrees N, Elevation:6000'
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Yes, insulating your freezer and fridge will make them more efficient, I haven't done this yet but I plan on doing it.  I recall learning about how those mini fridges use just as much energy as a regular sized fridge.  And those stand up fridges use a lot of energy.  With a large enough system, it doesn't matter.  But on an 800w 24v system....you may wanna crunch the numbers.  You'll likely find that the fridge eats up more energy than anything else.  A simple way to get an off grid fridge is to convert a chest freezer to a fridge using a temperature controller.  I use a digital one from johnson controls, google/amazon, johnson digital controller. I think the A421 is the most current model..??  It's very simple, program your controller and then route the temperature probe into your chest freezer....it turns your freezer on and off and keeps it between the temperature you set. 

Some things that suck about a converted chest fridge compared to a standup fridge.  The front and side wall on my chest fridge must be where the cooling coils run, if any produce is touching the front interior wall, it'll freeze and become ruined, and I had two melons touching a side wall and part of the melons froze where they were touching. I still have yet to do it, but I think a thin insulating board may prevent this.  Another thing is condensation collecting in the bottom of the fridge, so make sure your fridge is set up so that the drain is the lowest point.  You'll have to remove the drain often to drain the water.....inserting some tubing into the drain and then creating a J loop outside the fridge below the drain would probably keep the condensation draining, and having the J loop would prevent too much loss of cold air....I think.  Someone told me of others doing this, but I've yet to try it.  And the most annoying thing about a converted chest freezer to a fridge is, organization.  It's a pain to need to lift and shuffle and move things about to get what you want at the bottom of the fridge. Under everything else.  But if you organize instead of just cram stuff in..."I crammed my fridge on the last grocery run"...then it's not too much of a hassle to get at what you want.  Thought of another one....make sure your temperature probe is secured in place.  I had it fall out one time and so it froze what I had left in there.

I have a 600w 24v system, and I run a converted chest freezer fridge.  And a small chest freezer.  My fridge is a big one too...and as I recall, the energy consumption doesn't go up too much as you step up in size.  And keeping your fridge full will reduce the energy used.  One more thing I noticed that may be worth noting for some...if your fridge is nearly empty and you go for a grocery run, once you fill your fridge it's probably going to run for a few hours to bring the temperature back down.  Could be useful info..??

Manual disconnects for your system.  I used disconnect switches from waytekwire.com  I over sized them for what I need.  I think these are the ones I used. https://www.waytekwire.com/item/78405/Blue-Sea-Systems-6006-m-Series-Battery-Switch-/ ; I think I have three.  Between the solar panels and charge controller, between the batteries and charge controller, between the batteries and the inverter. If the link dies, go to their site and go to products>switches>disconnect switches.  I have a 24v system but got 48v switches.  Two position only...on and off.

Keep space between batteries so air can flow between them, instead of pushing them close together.  I didn't do this.  I learned this after I had my system set up.

Leave enough wire and route it properly so that you can get you battery caps off.  I didn't do this either.  I had the routing all nice so that I could get to the caps, but realized after I had everything set up that the caps can't fully come off without me loosening the connections and moving wire around.

I have the go power 3000w pure sine too.  It's been working everyday for the past year.  I also don't run too much electricity.  I'm about to set up a washing machine.  The trick is to run it while the sun is out, and the sun is out nearly every day here.  I'll do loads of wash during the day while there's plenty of sunshine left to make sure that if I used anything out of my battery storage then it will be replenished before evening.  I'll have to look again, but I think a washing machine uses around 600w, so long as there's no heating coils for any reason.  I don't know much about them, but I plan on running it on cold/cold just in case it has heating coils.  PS...on the topic of washing machines, "because I brought it up", the new HE machines are overpriced junk in my experience.  They don't get your clothes clean at all, and they constantly leave soap residue in your clothes, even while using small amounts of bronners.  And most all are front load or top load with locking lid, which is a nuisance when you find that one sock you dropped on your way to the machine.  LOL  I don't like em.  Get ya a speed queen I got lucky and found a used one.


Some tidbits that may be of interest.
 
Jd Stratton
Posts: 21
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If the cabin has a floor, why not dig a small hole (VENTED) and put those batteries under the floor?
They need to be away from you but they will not freeze under a heated cabin. (Besides, if you dig a bit, you are really making a mini-earth ship for your batts

Same thing for the freezer. We put ours outside in the winter. No point using all that solar to fight the wood stove.
You can also vent the fridge through the wall with a small fan, so in the cold the temp will be from the outside temp and not your sun power.

We used these in the 10watt variety. Great for path lighting. VERY weather proof.
http://www.ebay.com/itm/12V-24V-10W-15W-20W-30W-50W-60W-Cool-White-LED-Flood-Garden-Landscape-Boat-Light-/232404760618?var=531688559182&hash=item361c67382a:m:mau16ZyisUnQTF9EtinE_ow

We ran them on a regular 120V light switch...even though some will scoff at that. In the lower amperage, you will be fine to use the 120VAC stuff to switch 12V/24V lighting.
A simple inline fuse of the proper is all you need. The fancy ones cost a lot but they don't make your rig any more safe.
We used the .99 cent plastic fuze holders with some super sensitive fuses that I cannot find at the moment...sorry!

That system you have there is a great size and you have enough batteries if those are group 24 sized.
We have three 330 watt panels that actually max out our charge controller. We get 60 Amps into the batteries anytime from 10AM to 4PM-ish if needed.
We have found that using the sun power direct after the batts are topped off (They top off for us by 11AM) helps with large loads.
We have a small Xantrex inverter. This one: https://www.ebay.com/p/Xantrex-Prowatt-SW2000-806-1220-2000-Watt-True-Sinewave-Inverter/1900002456?iid=352095945891
When using our microwave, it is tapped out to the max. (It works, but at its max.) If we are using it for more than warming a cup of tea, we usually do so during the "peak solar charge" time.

Not sure what you are going to use to wire your inverter, but the wires that some people use make problems.
I used "0" gauge welding cable, (double plus the size of average jumper cables) and it made a huge difference.


 
frank li
Posts: 193
Location: Michigan
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Jd Stratton wrote:

We ran them on a regular 120V light switch...even though some will scoff at that. In the lower amperage, you will be fine to use the 120VAC stuff to switch 12V/24V lighting.
A simple inline fuse of the proper is all you need. The fancy ones cost a lot but they don't make your rig any more safe.
We used the .99 cent plastic fuze holders with some super sensitive fuses that I cannot find at the

Not sure what you are going to use to wire your inverter, but the wires that some people use make problems.
I used "0" gauge welding cable, (double plus the size of average jumper cables) and it made a huge difference.





I wouldnt quite scoff at AC rated switches, myself. I have seen them used, even helped replace some with people who were set on using them for dc lighting and had for years. We did lower current on all switches to about 1 amp and regulated at 13.8vdc.  Some of the old switches were smoked and flashed brightly during operation at low load levels.

They are inadequate and potentially unsafe.
I wont scoff at the idea or people who chose to do what they do.

I would try to find a good dc rated switch. Rv/marine, automotive or machine automationand control.
A midnite breaker makes a uber safe and long lived dc switch and fuse all in one for about $7.
These breakers will switch at full load over a million times and are magnetic/hydraulic actuated for safety. The contacts in a dc rated switch resist pitting. This reduces arcing. The device can also contain the dc arc that occurs. Being listed helps with code if applicable and with safety concerns aside from.

The manual calls for #2 and 200a fuse!
If using a 200a fuse, better to have 2/0 cable. The thing can draw at least 125a at full power, plus surge and if your dc loads are on this cable also, a little headroom is good.
 
Jd Stratton
Posts: 21
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frank li wrote:
They are inadequate and potentially unsafe.

Well now that qualifies as a "scuff" if not a full "scoff."

(Lets put this in perspective.)
        Sleeping in a shack out in the woods is potentially unsafe.  Sharing breathing space with a wet cell battery is potentially unsafe. Not having a 911 approved address is potentially unsafe. Not using zoning-approved toilet facilities is potentially unsafe.

If someone has an old A/C switch hanging around with a box on it, like we have all seen 20 times, I would rather see them use that than what I often see controlling the lighting in off grid installs...
(...an alligator clip with no fuse, taped to speaker wire from an old CJ-7, stapled to the wall in between open splices.)


Running less than 15 feet of wire on micro loads using proper fusing, I can assure anyone it will be a lot safer than the alligator clip.
In fact, I bet there are members here who control their lighting that way...even have their kids doing it...when an AC switch would be a much safer option.







 
Dale Hodgins
garden master
Posts: 6690
Location: Victoria British Columbia-Canada
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Here is something that I have done when using a chest freezer. I didn't use it on a solar-powered system but, that shouldn't matter.

 I had a chest freezer, but no refrigerator. I always kept a few 1 gallon jugs of water, frozen. On occasions when I wanted to cool something, but not freeze it, I would simply move a frozen bottle, to a good quality Coleman cooler. It had quite thick sides and of course was top-loaded. Items stored, cooled off nicely but didn't freeze. I always kept a thick duvet over the cooler when it wasn't in use.

I have also covered the top and sides of an older chest freezer, with a large duvet, when it's not being opened very often.

Suppose, that you have a chest freezer that is only half full. The remainder, could be filled with jugs of water, on sunny days when you have an excess of power. Then, when you harvest a bunch of stuff and want to freeze it, you can start off by placing it in the separate cooler, with a couple jugs of ice. This will reduce the load on your freezer. Stuff could be held over for a few days, until the sun returns. That would prevent the warm produce, from raising the temperature of items that are already frozen.

My place often experiences hot days followed by quite cool nights. I have used the milk bottle system, as my only refrigeration. I set the bottles on the roof of the car, in the evening, and by morning they are quite cold. There's certainly a bit of pissing around with a system like this, but I could see automating it, if someone were dealing with large quantities of harvest that needed to be cooled, before entering the freezer.

We had some work done to the house once, and it was necessary to have the power off for an extended period. I turned the refrigerator and freezer to their lowest setting, in anticipation of this.

This all assumes that you will sometimes have excess power, which I hope is the case.
 
frank li
Posts: 193
Location: Michigan
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Jd Stratton wrote:
frank li wrote:
They are inadequate and potentially unsafe.

Well now that qualifies as a "scuff" if not a full "scoff."

(Lets put this in perspective.)
        Sleeping in a shack out in the woods is potentially unsafe.  Sharing breathing space with a wet cell battery is potentially unsafe. Not having a 911 approved address is potentially unsafe. Not using zoning-approved toilet facilities is potentially unsafe.

If someone has an old A/C switch hanging around with a box on it, like we have all seen 20 times, I would rather see them use that than what I often see controlling the lighting in off grid installs...
(...an alligator clip with no fuse, taped to speaker wire from an old CJ-7, stapled to the wall in between open splices.)


Running less than 15 feet of wire on micro loads using proper fusing, I can assure anyone it will be a lot safer than the alligator clip.
In fact, I bet there are members here who control their lighting that way...even have their kids doing it...when an AC switch would be a much safer option.




Fair enough!  We have seen some of the same and most people dont zorch it up. I have seen a whole 2 level, multi room cabin with a quarter mile of #22 ga. wire embedded in the logs and all clamped right to the battery posts without fuses, for years. They run ac switches too. 

We all use our best judgment and resources.
 
Dustin Nemos
Posts: 95
Location: Central TN
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Oh boy I'm brain fried already, let's start slow please I have a box of stuff and a plywood board to attach things to. I like the idea of putting the batteries under cabin but not sure how to dig a hole under it with all the rocks I have to pick the top two feet to dig here. I need to work on the interior of the house parts I don't yet have my charge controller or pv panels in the mail. I want to put the main parts neatly on plywood and in a fairly tight space could someone help me figure out what order they go in? Maybe on paint or something simple? I figure I'll get the main parts up and then connect them..? I don't know what a big baby box is btw.

Also I don't yet have the clips to attach pv to the unitstrut 10 feet bars, I did build a 10 x 10 x 8 h tower to attach the bars to (unitstrut to L beams to wooden corner posts should let me angle it up and down in winter. I need to keep this as simple as I can but I do want it done well maybe if you guys could/would help me on one stage at a time as needed. Lots of great advice so far but info overload is frying my brain
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Dustin Nemos
Posts: 95
Location: Central TN
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Batteries I have are Duracell sligc110 6v golf cart batteries from batteries plus.


By the way, can someone explain how it works to use both do for lights and Ac for others? I bought this system from backwoods solar specifically to scale up later in panels for more power as needed. I have 3 290 panels now on the way. I'm interested in getting advice on the slr200 end clamp and slr100 mid clamp and the weeb wmc  grounding clip? I know it all needs grounding but I have no idea how to attach grounding wire to the individual metal parts and I wanna do a quality safe job my pets and pregnant wife live with me in this tiny cabin
 
Joshua Parke
Posts: 108
Location: Northern New Mexico, Latitude:35 degrees N, Elevation:6000'
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I built my PV stand out of wood posts and 2x4's, "temporary location", so I can't offer any insight into that.

But I think you're also asking about the order of connecting electronics together so you have a working system..??  I'll explain it below, and I can get a picture of mine so that the explanation will make more sense if needed.

PV panels to a switch then to a charge controller.  Charge controller to a switch then to the batteries.  Batteries to a switch then to a fuse then the inverter.  Ground your inverter, and your battery bank.  I had read that it's best to keep your charge controller and inverter close to the battery bank, which makes sense...less wire to run and less loss of power.  The more wire you use between your charge controller and batteries and inverter, the more power you'll consume just to push it through all that wire.

Running your DC lights off the battery bank is simple.  If you have 12v lights in your cabin, but you have a 24v battery bank, then you'll need a step down transformer.  It may be called converter instead of transformer.  Check their rating for how much power they can handle and ensure that your DC powered electronics, while they're all running, won't go over the rating of your transformer, otherwise it'll overheat and give up the ghost.  But I would imagine that they make DC lights/electronics that'll work on a 24v system so that a transformer would be unnecessary.

So basically you'll need to run wiring in your cabin that is connected to your battery bank for running your DC electronics.  And run separate wiring, connected to your inverter, for all of your AC powered electronics.
 
frank li
Posts: 193
Location: Michigan
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Could you post a few photos of the whole bag-o-cats!?

This helps. I can see alot from the part descriptions, but "tab a" to "tab b" and across many industries for supply caused differences in parts specification and arrangement.

Things like "do i need an industrial set of crimpers or fixture for cable crimping? "Are these lugs suitable for fine stranded wire termination with set screws?", and such come up and seeing the parts all laid out is helpful.

I do not see pv module mounting parts, rails, Ls, clamps, etc., listed there.

You will want an ac and dc distribution panel or power center. This can be built from purpose built gear, electrical supply house gear, rv/marine gear or a mixture of the available stuff that suits your build.

The links above for this stuff would likely suit your installation. Square D makes some dc distribution like normal building electric.
These work, but a machine panel enclosure like a midnite epanel or dc load center gives a place to bring all this together in one hub, and can handle ac and dc in one enclosure, simply select appropriate breakers, lugs and wir/cable.

Cost is comparable to the clutterbox hall of shame and safety and capability is improved..over alligator clipping it up!

The blue sea 3-12 or so automotive style distribution/fuse box can work well for cabin power. At $30-$40 are inexpensive, marine grade, high capacity with stud type feed terminals, stainless fasteners, heavy plated copper bus, common auto-blade type fuses.

I would review system schematics that suit your project outline as a start. The ones in bacwoods solar were always great and most suppliers and manufacturers supply these. You will need to be totally familliar with what is required, how and why you are connecting this equipment in the order that is required, limitations of your materials and have knowledge of the operation of the system and its components.

No zorching!

Other than this, it would be cool to make an epic post of your project step by step, starting with the battery, its support (enclosure, shelving, main fuse(s) close to positive battery terminals, cables, fusing ventilation, leak catchement, watering provision, etc).
Not that all this must be included, just possibles.

Breaking it up like this will help make your salad less tossed!

It will also make solving the common issues a bite at a time affair. Dont worry about panels permanently until your battery inverter and load center is all squared away as this area takes the most thought and care.

Space is at a premium, but dont cut the floor or dig any holes yet!

Once you have your storage settled you can temp power in from pv or use a charger if needed.
as long as all batteries are within 10% of each other in soc, they should be fine to interconnect and wire. Major differences or extremely low soc batteries will sometimes not power a controller on (protection).
Also you may not want high power transfer between widely differing socs. Pow.

Usually not an issue. But they did say so on your bill!

Your inverter and all the electrical gear laid out on a piece or two of plywood like you describe is common and generally suitable as you need a place to use as a canvas that is easy to attatch to, especially wires, conduit and enclosures. Then you will only have a couple-four holes to mount everything securely and or remove it entirely with less fuss.

You can jumble the bits to suit the area you are hanging it in and the relationship of all the inputs and outputs will direct your battery box layout and possib-likely vice versa, integration!








 
frank li
Posts: 193
Location: Michigan
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http://www.midnitesolar.com/pdfs/mndc125_250_manual.pdf

This manual has great schematics and photographs of the wiring and fuses, etc, for a system like yours. It is close and you can possibly ignore the enclosure.

 
Dustin Nemos
Posts: 95
Location: Central TN
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Holy cow man ....confused. How much of this goes on the plywood so I can cut that and get started...
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Dustin Nemos
Posts: 95
Location: Central TN
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Got a diagram from backwoods solar now too for my system, it might help a bit but I'm working with very little room I need to get the plywood cut ( maybe osb if it matters)
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frank li
Posts: 193
Location: Michigan
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A "big baby box" or the small, are compact breaker boxes from midnite that hold ac and dc breakers. You could use one for your dc side, controller, pv in, dc load out and another for ac side, four breaker slots each. These are tiny.

A Square D, QO load center or similar is about $30-$50 and serve well for ac distribution with few circuits.

You could  probably place two baby boxes, your inverter, fuse and charge controller and a few labels and call it good on a 2' square of plywood or less.

Or even wire it all point to point with fuse holders and or breakers on din rail, open board, which ive also done...some build a ventilated cabinet over them.

If you get into automation and control parts, you may be suprised how compact all this can get, but im not sure exactly where i got the idea that you didnt have space.

I prefer the closest midnite epanel that suits your inverter, or the nottagutter...ac and dc in one enclosure!

A regular load center (main lug or main breaker panel) and a midnite mini dc plus is a sweet way to get all the bits in few boxes.

The mini dc plus ($200) has something like 10 din mount breaker slots, an inverter/battery breaker, place for shunts and it has bus bars. An epanel runs about $400 but has more of everything, wiring space, bus provisions, bypass, breaker slots, knockouts, possible to mount your inverter on the door and midnite classic sidemounts on the included bracket, space for the trimetric, whizbang jr, and shunts... the whole shebang on a 22"w x 30"t panel board.

Midnite also makes a stand alone manual bypass interlocking breaker set that can conduct safe transfer to a generator/grid if using them. Unless its a one source show for ac power, these are great.
 
frank li
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Looks like they took care of you ok. The drawing looks usable. Cables look good. Hate the fuse blocks, but as long as they fit the type cable you have, and have appropriate fuses, they are fine.

No fun without the controller! Get a nice piece of plywood! Hardwood will take screws much better and you can show people! Beats hiding it and making excuses for osb for years.

If it matters? It may not.

Batteries, are they there? You could have power on, at least or able to be on.

When you say unistrut, are you talking solar rail? or industrial mounting strut?
Again, if you are using a pv mounting system, it will be fairly straight forward.

A battery fuse/breaker should be within 4" of the battery positive terminal. As close as practical is better than not at all or on the far end.

The controller needs a fuse/breaker between it and the battery and it and the pv.

*Any load or source wired to the battery for dc power needs a fuse/breaker

Switches are recommended, a breaker does both. Fuses, cable terminations and pv connectors are not disconnects and some points need a switch. (Fuse/breaker indicated, fuse at a minimum if devices have suitable on and off control.

Uggh, inrush current destroys fuse, screw and lug terminals, all im gonna say, except i have also done this.

You have time to juggle pieces and order/wait for more! At least there is that.

Battery box!










 
frank li
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Location: Michigan
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See the drawing, where all the wires come together on the main positive terminal?

That is going to be an issue without a terminal bus. Or other suitable distribution and fusing. Blue sea terminal block next to the cc fuse? This would allow some circuits.

This is your friend and $12 each is cheap unless you have a chunk of pure copper plate or bus,

even then!

http://www.midnitesolar.com/productPhoto.php?product_ID=97&productCatName=Busbars&productCat_ID=17&sortOrder=8&act=p

The busbars on this page may help free range up a panel board. They are cheap for what they do.
http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=17&productCatName=Busbars

The shuntbus goes on the shunt and is just anregular bus bar they can solve some issues, but you probably need two large ones for ring terminals and lugs all around.

I like that backwoods still show how to wire a battery in parallel and balanced diagonally across the strings. Powered off the opposite corner terminals of the bank of strings.
 
frank li
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Location: Michigan
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It looks like there is no main battery cable fuse for the inverter. There is one in the drawing and there is an internal fuse mentioned in the inverter manual, but i dont see one for that cable.

Car audio may have what you need. Marine or car audio ANL or class T are generally used, some glass cartridge, other.

Its a good idea to fuse the main positive at the least, if not both and arguably both positive and negative and all interconnects!

Kidding. It gets deep, but a fuse at the start of the main positive battery cable going will protect it and your safety.

 
frank li
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Now, the 30' of pv wire with connectors is a 15' whip after cut in half for a set, male and female. This pretty much just gets you to your combiner, where you can easily add 2 more strings of three or add a module and switch to 3 strings of 4 depending on voc vs max cold temp., for addition of pv capacity.

If you are not going to add modules later, you could use the combiner on your panel board, but id assume the best overall is to use it to transition/splice to conduit, direct buried, or overhead wire for the home run and leave it, its bus bar and ability to add pv later for sure. But a splice could possibly be done with mc4 connectors.

How are you bringing pv home to the control? Are you building a wire sized for addition of pv on that circuit?
 
Dustin Nemos
Posts: 95
Location: Central TN
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Frank I barely follow you brother, I will get pics of my unitstrut from Home Depot when I can, I am building an osb box for the batteries today and would prefer plywood for the power center area but I have so many needs and not enough dollars, I'll have to pass on vanity and just settle for safe efficiency. I do have a mind for long term but I cannot follow the advice you are giving can you dumb it down a bit for me and if I need parts they didn't provide tell me what to buy? Sorry for the trouble! I do plan on upgrading more panels over time but not likely ever more than 3000 watts my inverter maxes there.

I was worried about splicing 5 cables into that battery too I figured I might need a bus bar but would I install that inside the battery box? And since I need to keep batteries close by inverter I guess for now I'll put the bat box outside behind the current inverter in the picture at the back window and keep the box off the ground, paint it well, and put some metal roofing pieces on top to keep it dry. At least til I build room 2
 
frank li
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Ok, i re-read to here.

The coil of black wire with connectors on it, one male and one female. These plug into your solar panels and the ends go inside the mnpv3 combiner and land on the terminals. Positive on the breaker and negative on the negative bus.
There is a breaker bus for combining breakers onto a single wire (sometimes a paralled set of wires) to go home to the classic charge control. The combiner takes strings of three panels and combines them up to 3 into 1 in the case of your mnpv3. And since you are looking to add later, i would install the bus and size the wire for three strings and 1% -1.5% loss max.

100' or less panels to controller.

One string of three panels- #8 (or #10 minimum) will do, especially for temp-ed in work to maintain batteries or otherwise get by.

Three strings of three- #6 works real well for one string and barely for three.

#4 is likely your wire if you can spare the extra few cents per foot. 200+ feet and a minimum #8 ground though!
This is a decent home run wire sizing, as long as it is inside of 100' of wire. Even 10' can upset the loss factor if we are riding the edge of acceptable and there is more wire and connections involved after charge control and before the combiner. I neednt be hyper critical and is not life support, but...

Wire is permanent performance. As long as its not grossly over-done, its not a waste and is often the only area that can be hot rodded or improved on within a system.

There is a solar panel breaker.
There is a charge controller fuse.
The battery interconnects if #2, are a bit puny, but should be okish. Better to keep all one size and protect at that level.

*You should get a fuse for the battery and battery buses for accomplishing connections at the battery terminals.
Its the only thing aside from distribution and disconnects that is missing. Buses inside the battery box, they bolt right to the terminals.

The battery main fuse and shunt should be outside the battery box, possibly in a space divided for power electronics with a cabinet stlye door or access hatch screwed on, even. Corrosive fumes. Some fuses contain the blow out and are sealed against infiltration and explosion of gasses, but the spring and wire terminals and other metal parts are only so corrosion resistant to the misting that goes on. Marine equipment is resistant to corrosion, but acid mist and spittle will kill most anything... catch 22.

*you should avoid unistrut if at all possible unless it is sub structure and you dont plan on securing panels to it, even then its heavy, expensive and ghastly (rusts where cut unless sprayed with cold galv or paint) not as adjustable and does not have listed integrated ground like pv rail mounting systems, although it can be bonded to ground.

solar mounting rail is cheaper and compatible with ground bonding to panels and other parts.
I will wait till i hear more about mounting before i make more of feet in mouth or offend someone.

Dont get me wrong, i have used osb shipping crates from inverter systems as enclosures, mounted solar panels on the wood pallets they shipped in on and ballasted them with rocks, screwed solar panels to 1"x2" pine, used a glass kombucha bottle as an outdoor rated combiner enclosure (wire nuts in an up turned bottle, more than once!), spaghetti wired  point to point with parts all over the wall and no touch safe protection or covers, used non sunlight resistant-non burial rated wire in the sun and or shallow buried, you name it, in order to getter done for myself and others in a pinch.

I cannot ever reccommend most of these methods. If anything, it worked and was safe by my determination in each instant case, at least until it could be done right or for a short term project.

https://www.zoro.com/square-d-load-center-lug-70a-120240vac-1ph-hom24l70s/i/G2174934/?gclid=COLpz6bsh9UCFQgQaQodN_cCTA

https://powerwerx.com/blue-sea-5026-12-circuit-fuse-block?gclid=CNi1nv3rh9UCFRGewAodM4sPVw


https://powerwerx.com/mrbf-terminal-fuse-block-300a?gclid=CIL7leXrh9UCFQQvaQod1fgO6g


https://powerwerx.com/blue-sea-2300-common-150a-busbar-10-gang-with-cover?gclid=CPLY0KHrh9UCFRO2wAodVOIFOA

You can get this stuff at cabellas, west marine, mom and pop marine stores, etc.
Powerwerx has a nice selection  of dc power acceseories.

There may be a place for a dc converter. What are you pumping water with?
Lights, pumps, usb chargers and other appliances are available at 24v (8v-36v spread sometimes).

Placing dc loads on a switching power supply will keep the lights bright and the pump running the same speed regardless of battery state of charge.

We can explode our heads on that one later but you likely wont have to have one anyway.

OSB is a fine material, the powder coated aluminum of the rural-off grid masses!

Your battery footprint is around 18" × 46"  if grouped tight in a rectangle of two rows. Not sure of your confines.

The temptation is to do something, anything, but having all parts present, lets the legos fall where they may, so to speak!
 
Dustin Nemos
Posts: 95
Location: Central TN
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I just need to pump water about 100 feet uphill later on but no pump decided yet.

Also another diagram from the backwoods solar guys. No charge controller (it's on way) so I was going to finish battery box and wire them up together as per the first diagram they showed me and then go in the house from there to the osb board and begin with the first piece of hardware, do I need any other parts to complete this job? One small step to get me started here would help. And if I'm bringing wire from underneath in the building where do you suggest I place object 1 on the board? Bottom left and work my way up from there clockwise?
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Joshua Parke
Posts: 108
Location: Northern New Mexico, Latitude:35 degrees N, Elevation:6000'
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Dustin - I'm unsure I can offer much advice on what you are asking help for.  I'm still new to solar setups and all the different components that can/should be installed.  My setup is fairly simple at the moment.  I'm sure that I could figure it out if I had all the parts before me and I knew what their purpose is.....along with some help from google.

I was wanting to say that you can have a PV system that is larger than your inverter if so desired.  Your charge controller limits the amount of PV panels you can string together.  So say if your charge controller limit is 1000w at 24v, then that is the max amount of panels you can string together on that one charge controller.  BUT, you can have multiple charge controllers each connected to their own individual string of PV panels, all connected to the same battery bank.  So essentially you could have a 10kw system, and still only be using your 3000w inverter.  The inverter is what converts DC power from your battery bank into AC power for your electronics to use.  And the charge controller is what limits the size of your PV panel string.  And you can connect as many PV strings, each with their own charge controller, to the same battery bank.  Did that make any sense??  It makes sense to me...LOL

Example -- Say that you want a 10kw system.  The charge controller limit is 1000w at 24v.  You have a 3000w inverter.
You'll need ten charge controllers.
You'll need ten PV panel strings where each PV string is 1000w at 24v.  So if each panel is rated 200w at 24v then you'll need five panels to complete one single string.  So you'll need in total, fifty PV panels at that power rating to create ten PV panel strings that provide 1000w at 24v per string for a total of 10kw at 24v combined.
Then you can connect all ten of those 1000w 24v strings of PV panels each with their own charge controller to the same battery bank to get your 10kw system.

Then your inverter limits how much AC energy you can use at any one time, through that inverter.  So if you have a good idea of the power consumption of your electronics and how often you have multiple electronics running simultaneously, then you'll know how much wattage you're going to need at any given time and whether or not your inverter is sufficient.

Hopefully something made sense, and helps out a little. 
 
frank li
Posts: 193
Location: Michigan
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Yes, on the leg of the pv tower or other suitable location will be your combiner. Placing it at a level that is easily accessed from the ground is usually a plus.

It can be tucked up high, but home-run wire/conduit length.

Direct burial wire should be used if not using conduit. Aluminum is reportedly not a good choice for dc power, for some reason i have not understood yet. Corrosion.

https://www.wireandcableyourway.com/4-awg-xlp-use-2-rhh-rhw-2-building-wire.html?gclid=EAIaIQobChMI0KiX_c-J1QIVFJd-Ch2pcQclEAQYASABEgIGB_D_BwE

The ground wire back to the electronics need only be #8 and coild be solid, bare copper or the use-2 wire #8
#6 is used where run in less supported or less protected areas than conduit or trays, basically.

Use good, well fitting strain relief fittings (cord grips) for burial wire into/out of enclosures. These grab and seal wire entrances while giving good support and protection to the area around being grabbed. They seal out pests and weather.
This includes pv wire. Usually one or two hole glands, also available with up to 5 holes and more or you punch.

http://webosolar.com/store/en/pv-cables-connectors/840-heyco-12-1-hole-nylon-npt-strain-relief-cord-grip-.html?gmc_currency=2&gclid=EAIaIQobChMIq9mn0suJ1QIV05d-Ch2kdgYmEAQYAyABEgI_S_D_BwE

The combiner ground bus can land all grounds and send an appropriate wire to a dc ground rod at the array.
Your pv combiner mounted surge protector, midnite SPD shunts to this system. 

Your layout is fine. All heat makers and displays up top, fuses down low close to the battery and other bits you dont need to look at too much are below.

If you dont have to stoop over your battery box, its a plus. It is done quite often because space is tight.
Are you placing batteries inside or outside?

The only thing you will likely need are zip ties, wire, ring terminals, small fuses for loads like meters etc, if they arent there, some screws, wire staples, sealant, etc.


How are you feeding the inverter output to loads, lights, outlets, etc?




 
frank li
Posts: 193
Location: Michigan
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Dustin Nemos wrote:Been trying to get all my parts together as well and have come across some parts for clamping solar panels to unistrut and I do not understand the seen wmc grounding clip part, any advice or links to diy guides here? Or how to attach grounding wire to the various metal parts I don't understand how those lugs work, or any of the little pieces that would hold the wires to plywood if I create a power center to help organize


Do you have a photo of these parts? Maybe a photo of the actual power center laid out on the floor, atop its osb. You can outline the classic control based on its published dimensions and screw down. Caution to plan knock-outs well and be sure you have enough wire and or conduit space to go everywhere.

Leave yourself as much room between components as you can, unless exploiting certain relationships that complet a nice picture and path.

Try not to bend wire at hard angles or chew it up with strippers and routing. Nice sweeping bends where possible and neat tighter ones where needed. 5x wire diameter is minimum radius generally, not always true though.

 
M. A. Carey
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I can't help with the solar questions as that is my husband's expertise.  What I can tell you is that we have 480 watts of solar, Renogy Tracer MPPT solar charger, indoor shut off fuse box for batteries and panels, MeTer MT-5 meter to keep track of amps and watts coming in.

We use a small chest deep freezer, and freeze bottles of different sizes (2 liter, 1 liter, and quart size) plus we purchased some large Cooler Shock Ice packs, total of 6 to alternate, and 6 Coleman icepacks we bought at Walmart for $1.67 each.  These all go into the freezer on one side and are alternately put into our 70-qt Coleman cooler for our refrigeration.  We have a separate smaller cooler, also Coleman, to hold cold water and drinks.  The other side of the chest freezer is used for meats and vegetables.  I was always having an avalanche of frozen bottles and frozen food falling into each other until my husband built a small framed screen insert with a middle crossbar, that fits into the small chest freezer.  This keeps everything pretty much organized.  June is our hottest month, which can get to around 100 degrees, but mostly mid to high 90s, and the other months are very pleasant, with winter being around 6-10 degrees above 0 at the coldest.  I take advantage of the cool nights putting the thawed bottles of water outside on a metal bench scaffold that lets air flow through, even in the summer, as it helps to cool at night, and in the winter, the bottles and cooler shock ice packs freeze solid (I bought those through Amazon and bought the screw on lids).  I purchased 6 (3 per package) so I would be sure to have enough frozen to alternate in the hottest time of the year.  The smaller ice packs from Walmart, I use 3 of those, 2 cooler shock ice packs on top of and in between our food in the large cooler for my "refrigerator" and use the ice bottles in the smaller cooler for our water and soft drinks.  This has been working great for us.

Good luck to you.  I hope you get all your answers.

Edited to add:  As Dale Hodgins noted, I too turn off my freezer at night.  In the summer the freezer is on at 6am and off at 7pm.  As the days get shorter, I change my timer to go on a bit later and off a bit earlier.  I normally start changing the timer in increments of 10 minutes later/earlier every couple of weeks or so and by mid winter it goes on 8am and off 4:30 pm.  Being full of ice helps with keeping everything nice and frozen solid.
 
Jon Butts
Posts: 34
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I didn't read every reply but Home Power (.com) Magazine has been addressing off grid issues for at least the last 20 years. There isn't any question un-answered and the on-line subscription will provide all the education to 'do it right the first time'. Also there's free down load at their web site to get you started and even the AD are useful. 
 
Isa Delahunt
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I'll leave the technical stuff to others, but I have a lot of experience with living with a solar system.  There is no power grid where I am, and both my house and the school where I teach run on solar.  I've been solar for twelve years here, and before that no electricity at all, but the place I taught had solar.  Before I got my own place and system I lived with an old system desperately in need of new batteries, which was good practise for when I moved to my place and used an 15 watt panel and an old 12v marine battery (which is a step up from a regular car battery, but not by much).  Now I have a really nice set-up with tons of power, even unto running a planer or table saw, or even (gasp!) an electric iron, when there is full sun on the panels, which is the height of decadence!  I have a back-up generator, which I recommend if you live where it is cloudy in winter, but I only run it about five times a winter, once a week, mid December to mid Januaryish, in western Washington.  I also run it if I'm doing a building project with a lot of high draw tools going, because I don't like to stress my system in that way.  It's a good resource to have, and if you get a smaller portable one (Honda eu2000i is a good all purpose one), you can take it to where your work is on the farm and run tools that will make your life much easier. 

The first thing you need to do is rearrange your attitude about power.  It is finite, and with solar, even with a big battery bank, it is still finite.  It's a lot like using water from a spring that has a slow, steady refill rate.  You have to match your use with the replacement rate.  That means you need to set your low voltage cut-off at a point optimum for battery health and when you run out of juice, you have to accept either running the generator or getting out the kerosene lamps until you get some sun.  There is very, very seldom any reason to get to that point, though, unless something weird happens, because you have to learn to pay attention to your trimetric.  Put is somewhere you will be able to see it, somewhere you will constantly pass it, and look at it often (like a few times a day).  You will learn how to interpret what it's telling you about how much power is incoming and outgoing, and what battery percentage and voltage you have available.  Find someone to explain how to read the trimetric, and make them keep explaining until you actually understand it!  You can establish rules of thumb about what percentage battery and volts you need to maintain, for quick reference.  Even in midsummer, when you'd think there would be power and to spare, you still have to pay attention, because a panel breaker can trip or the like and you can not be charging.  No one is making sure that things are right but you, and the trimetric is your window into how the system is performing.  If you don't pay attention to your system, you won't get full use out of it and you'll have to replace the batteries sooner than you might.  There is definitely a sweet spot of power use, which you will find. 

The game with offgrid power is to use the power you need, and not use power unneccesarily.  That mean turning things off when you are not actually using them.  That seems obvious, but it's surprisingly hard, coming from the unlimited power-grid world.  You'd be surprised how much phantom loads draw down your charge.  I turn the AC power off much of the time, unless I need to use it.  My internet is DC, as is the refrigerator, and some of the lights.  I have a 12v Mac charger, my speakers are 12v.  It's not necessary to go crazy with getting 12v things, but converting 12v to AC loses power, and it all adds up.  You don't actually need AC most of the time.  You can also put the inverter in "search" mode, but that doesn't take care of the tiny phantom loads, so it's still best to unplug things, or put them on an outlet strip that you can turn positively off.  That's a good set-up for computer and phone chargers, which use tiny bits of power if you leave them plugged in.  It seems like a petty detail, but it all adds up, and in January, you'll be glad for the good habits you have developed.  12v LEDs or AC LEDs are the way to go, and you will learn which ones you like and which ones want to make you vomit from the shade of light they emit.  In the off-grid world, you learn to light areas differently, too.  Think about putting light where you need to see, not in every corner of the room.  Turn lights off that you are not using.  That seems obvious too, but it really makes a lot of difference.  Ikea makes a desk lamp with a little solar cell on it that you can remove and put outside or in a sunny window in the day and use at night.  You can definitely have really great light and computers and kitchen devices and power tools, and all that luxurious stuff we are fond of, you just generally can't run it all at one time, and you have to be disciplined about it. 

I have parallel AC/DC wiring, which is good, but not as useful as you might think.  It was pretty easy to do, though.  The outlets look different, so it's easy to keep straight, except for when you start running extension cords from an outlet.  I advise you to label any cords like that, or any light fixtures that you are running off something like that, because you can plug an AC thing into DC and it isn't a catastrophe, but if you plug your 12v light into AC you will ruin it.  Also, when you put a DC plug onto an extension cord to extend DC power, you have to pay attention to the + and -  so you don't damage your LEDs.  LEDs have come a long way, use them!  Superbright LED online is a good source.  There is a little adapter you can screw into your regular lamps and light fixtures so you can use the pin style LED lightbulbs.  There are 12V white christmas lights, which are the classic ambient walk-around-the-place-without-bumping-into-stuff solution.  I have a 24V DC freezer, and a 12v refrigerator, both Sundanzer, and they take not very much power at all.  I'll be adding a second freezer this fall.  It's very much worthwhile to get good 12 or 24v equipment like that.  You can insulate your old power hogs until the cows come home, but they will never be as efficient as a good purpose-built efficient DC unit.  (Another trick is to fill the freezer completely, replacing food as you use it up with plastic jugs of water, if necessary.  The unit runs less when it's full, and keeping objects frozen is easier on it than keeping air cold.)  In general, when deciding whether you can run a thing, either AC or DC, you can try it out cautiously and watch what it does on the trimetric.  You will find out that you can use some things any old time, but others you need to wait until at least daytime, and others need full sun on the panels, and others are just not happening, unless you run the generator for them.  Find out how to do the math for how much power a thing uses, if you are so inclined.  Plan your power use for the best time of day, for example get your computer and devices and such charged while there is sun, don't wait and plug them in a night, like you might do on the power grid.  Do the laundry when it's sunny, then you'll have power to run the washer and the clothes will also get dry.  It's all pretty fun, definitely not for the clueless. 

Finally, no matter what, you have to take care of your batteries!  Think of them as livestock, or small children, or something you tend, not something in that box over there that you can forget about.  If they need water, check it regularly, have distilled water on hand, and keep them at the right level.  I check my batteries monthly, when I pay bills.  Pay attention to your trimetric, charge the batteries if you need to, watch how you use them so you get full use.  This is complicated to think about but easy to do--find someone who can explain it to you and then follow whatever protocol you establish for drawdown rate. If you abuse the batteries, they won't last as long or work as well.  Start a battery replacement fund now, because they have a finite life, and a new set will be a sizeable amount of money, and it will sneak up on you.  And, having that little bill you pay to yourself every month is another reminder to pay attention and take care of your system. 



 
Chris McLeod
Posts: 57
Location: Cherokee, Victoria, Australia
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Hey Dustin,

I've been off grid for about 8 years now and rely on 100% solar. My place is in down under and we are about the same latitude (I'm 37.5'S and you are about 35'N).

Firstly, you have to slow down and go right back to basics. The reply from Isa above is one of the best replies so far to your questions.

Mate, I'm sorry to tell you this, but your batteries are not a fuel tank and do not work like a fuel tank. I can't put it any simpler than that.

They are instead a chemical reactor. And chemical reactions change depending on how hot or cold it gets.

Mate, you were writing something strange about putting your batteries in a box which may be subject to the weather. This is not a good idea.

The batteries should be kept at best at a more or less reasonable temperature.

Also if something goes wrong in the system and for some strange reason the batteries (I'm assuming that they are lead acid chemistry) get too much charge they will vent hydrogen and oxygen. You may recall the Hindenburg airship. That mix of gases didn't work so well for them.

If on the other hand you are using lithium ion batteries (which is a possibility) if you over charge them, they can be subject to thermal runaway and catch fire.

Neither option is good.

So I suggest you go back to basics and figure where you are going to place the batteries so that they don't get subject to massive swings in temperature.

Then from there, the inverter as you rightly put it, needs to be located close to the batteries.

When you figure that out, the next step is placing the charge controller nearby all that stuff.

Give us a yell. Or drop by my blog as I was upgrading my off grid solar a few weeks ago and there are plenty of photos.

Cheers

Chris
 
M. A. Carey
Posts: 26
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Chris McLeod wrote:Hey Dustin,

Mate, you were writing something strange about putting your batteries in a box which may be subject to the weather. This is not a good idea.

The batteries should be kept at best at a more or less reasonable temperature.
[END QUOTE]"

Regarding an outside battery box subject to the weather:

I will reiterate that the solar, including batteries is my husband's department.  However, that being said, we have lived off grid since 2002, first in a 5th wheel trailer and then a motor home.  During those periods, our batteries were in a compartment large enough to handlle them, and there was no slide out, but enough room for maintaining them.  We have been in a small cabin for a while and my husband built a battery box that was similar to the RV compartment.  Right now there are six 6-volt batteries in there, with room for two more should we decide we need more.  There is approximately 8 inches between batteries and the inside of the top.  The box is insulated with 1-1/2" styrofoam on all sides, bottom with thin plastic above the styrofoam (with small slant and drain for runoff from cleaning during maintenance), and the top is insulated, and shingled on the outside, which is slanted like a house roof. This top/lid, comes off to maintain and check the batteries.  We have siding on the outside of the box on all sides other than the shingled roof. The battery box is right next to our cabin, on the south side, where it is close to have all the wiring coming into the cabin and also close to the solar panels that are on frames and can be tilted, depending on the time of year.  The battery box has a small house-type vent on the west side and on the east side, one high and one low for airflow.  Our latitude is 35 degrees north, and we are at approximately 6000 feet altitude.  We have cold winters, with lows in the single digits at the coldest, but sunny days that bring the daytime temps up into upper 30s to 40s in the coldest part of the winter.  We have never experienced any problems with our batteries.  I'm just saying...it could be possible to use a battery box outside like we do, if insulated, vented, placed maybe on south side, and if it is not extremely cold like below 0.  I am no expert, but we have lived like this without problems.  Maybe we have been blessed to not have problems or maybe it is not a problem to have an outside battery box that is subject to the weather, if done correctly. 

This is just my experience with an outside battery box subject to the weather.


 
bruce Fine
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lots of great info here thanks everyone,
I have have more time than money and still gathering bits and pieces to put together system.
I found dc breakers for $0.50/lb at the scrap yard  and insulated wire is $1/ lb there .and free glass all I want from several different commercial glass places that do storefronts and doors and stuff,
 
Chris McLeod
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Location: Cherokee, Victoria, Australia
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M. A. Carey wrote:The box is insulated with 1-1/2" styrofoam on all sides, bottom with thin plastic above the styrofoam (with small slant and drain for runoff from cleaning during maintenance), and the top is insulated, and shingled on the outside, which is slanted like a house roof. This top/lid, comes off to maintain and check the batteries.  We have siding on the outside of the box on all sides other than the shingled roof. The battery box is right next to our cabin, on the south side, where it is close to have all the wiring coming into the cabin and also close to the solar panels that are on frames and can be tilted


Thanks for the reply and I have no particular problems with batteries being stored in a well ventilated box.

The thing to consider in these arrangements is that the battery charge controller possibly should have a temperature probe attached to the side of the batteries. The reason for this is that:
- In summer when the batteries are warm to hot, and yours are facing south so that the box they are in may receive direct sunlight as well as warm air temperatures. The batteries should be charged at a lower voltage than at colder temperatures. You run the risk of the batteries venting hydrogen and oxygen if you do not compensate for battery temperatures. Summers here can get over 100'F so perhaps this is more of a concern for down here.
- In winter when the batteries are cool to cold, they need to be charged at higher voltages because the chemical reaction is more sluggish. The alternative is that the batteries are undercharging during this time, and there is the inevitable risk of draining the batteries.

Most charge controllers have temperature probes attached to the sides of the controller - and that controller may sit inside a warm cabin rather than outside with the batteries.

As another consideration, styrofoam is a very flammable product - although as you correctly note - it is an excellent insulator. I believe this material was the possible culprit in the recent fire at the Grenfell Tower in London where I believe 58 people died (and maybe more). I'd suggest instead using mineral wool or fire check plaster, fibro cement as a possible alternatives.



 
Steven George
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Location: Finland, Minnesota Zone 4a
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forest garden solar woodworking
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I didn't read all the replies so excuse me if this has already been said.  For off-grid refrigeration, don't use the mini-fridge.... super inefficient.  Instead, get a 3 - 5 cu/ft chest freezer (made in the last ten years) and then get an inline thermostat converter like this Inline Converter

I bet you can find one cheaper than that if you searched around. 

My family and I have been living with our off-grid 1000w array for 5 years now running a chest freezer + a chest freezer fridge conversion with that inline converter.  We tried running a mini-fridge at first but soon switched over to the chest freezer conversion.  Make sure to get a chest freezer to convert though so you don't lose all your cold air every time you open it.  A little annoying sometimes digging for food but well worth the HUGE difference in energy consumption.
 
I agree. Here's the link: http://stoves2.com
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