Screw the Electric us off the grid..our story

brandywinebrandywine Registered Users Posts: 15

We newbs here in Appalachia need some advice from all you experienced folks out there.

We bought a farm here with a full time stream (not enough for hydro-darnit).
I started out with the idea of building a 32x32 cabin and sighted it out. Applied for a septic permit $500, so we could apply for electric. We wanted to build a shed/workshop first and live in that while we built the larger house over a few years (no mortgage).

Applied for electric. In TN, electricity is not a right and you have to get permission from every property that touches you and all that touch them to get poles run. Well, after 2 months with no progress we started thinking of options. We already started the prep for the SHED (The Shedteau @ Brandywine Farm).
Then found out you cannot get electric turned on (even if they ran the poles) until your permitted septic is signed off. You cannot get the septic signed off until it is completed by an approved contractor. We couldn't get the septic done because we would need a new plan for the SHED (another $500) and then the house would have to be under roof before it could be signed off to turn on the electric.

sigh. Screw that stupid bureaucratic pile. We decided to be off-grid for everything.

So we dug a spring box with filter system...water. CHECK.
Built a 16x24 Shedteau....CHECK.
Wired it with a very small entrance box 6 circuits..and hooked up a Troybuilt 7KW Generator. POWER...check.
Dug our own small 2-person Septic system...CHECK
(good enough for the Amish..good enough for us)
Put up Cell antenna booster with Yagi....Communications..CHECK.

Now for the next steps. After reading a lot and learning some electrical stuff.
I measured our electric usage with a meter.

Tot Watts possible 5409watts (Phase I=2790, Phase II=2620)
Total daily load (Wh/d) 8019.9 Watthours (Phase I=5034, Phase II=2985)
days of storage 1 day
Battery voltage (Vbat) 12v
Battery Capacity Needed 1336.7Ahrs
Batteries Needed =9 batteries

So, I bought

6ea 181AH lead acid batteries (getting 3 more)
Xantrex SW3000 Freedom Inverter/Charger (3000watts/6000surge..150amp charger)
8Kw Troy Built Generator

Will be done in 2 phases.
Planned: Solar Panels later this year.

The install guide that came with the xantrex is a bit confusing.

My questions:

1. When we are running the generator...the inverter will be bypassed (i guess per the install guide). Will it still be charging the batteries even while we are using some power in the house?

2. Since our total wattage that can be used at one time is more than the 3000w we will do it in 2 phases, we will need to get another inverter/charger...will that have to be on a completely separate system .. battery bank etc?

3. How can we insure that our refrigerator won't go out for any reason...any type of redundancy that we can do?

Suggestions for system in total?

The battery bank must by 12v since the xantrex will only do 12v batteries. We want to make our solar panel array 48v and step it down (eventually).

We appreciate anything and everything. There sure isn't a lot of info out's scattered.

:grr P.S. Over 4 months and not a peep from the power company. NO phone calls, letters, nothing. We are so cozy in our little shed, we may never build that 32x32 mansion.

Mickie & Travis
The Shedteau @ Brandywine Farm


  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story

    welcome to the forum,
    try to keep expletives to a minimum as the forum is family oriented in that anyone could read it without getting offended by the language or have a kid reading here ask their parents as to what was meant by s**w the electric company.

    anyway, you aren't alone as many get caught up in either red tape and/or high costs just to get to pay the electric company $ every month. a system needs to be worked out on paper long before you buy anything so that you can try to meet your needs best and i see you have started in that attempt. better to mess up on paper than after buying lots of stuff.
    note:---oh no, now in looking back i see you prebought this stuff so some of my comments don't apply. you may want or have need to send some back for a refund or other stuff depending on the conversation results. ready, fire, aim syndrome again.

    1> in theory it will charge the batteries and the loads if the generator is big enough to handle both and accounts for power factor and other efficiency factors. some inverter/chargers let you tailor the charger, but a big battery bank will need around a 10% charge rate and can be roughly between 5% and 13% for most batteries and there are exceptions. you did not mention the voltage of each battery or the type to make specific comments on.

    2> it's good you mentioned this ahead of time as there are cheaper and better ways to go about this. would something like this fill the bill a bit better? see the 6048 specifically.
    that not only handles the power you may want, but does it in one unit and allows for a 48v battery bank that i'm quite sure everyone here will agree you should have. this will influence the battery bank configuration obviously, but no matter what you will need a large battery bank to handle 2 separate 3kw inverters and the wiring at 12v will be very large if not impossible for you if made to operate with little loss. of course there are other inverter manufacturers to like magnum and outback and for that possible power level only think 48v battery banks.

    3> good question, but no easy answer. not even the electric company can say they will never fail, but it will depend on you as to what may work. what i did was i wired my refrigerator to my kitchen light. if that light fails and the bulb is good then my frig is out too. this gives me a readily visual indicator of my frig status. if you are away or sleeping you may need to come up with other ideas and that could be a thread all to itself.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Screw the Electric us off the grid..our story

    Well you are not having a good time, are you? :cry:

    I feel like a heel but I'm going to have to add to your misery.
    First, 8 kW hours is a lot of power in the off-grid world. Some examination of usage is in order there to see if it can't be reduced. Producing that much power will cost a lot of money.
    Second, if you do need that kind of power do not use a 12 Volt system. 1336 Amp hours of battery will be a nightmare to charge. 9 batteries in parallel will be a nightmare to keep balanced. Running a single 5kW inverter from 12 Volts is on the "DO NOT DO THIS" list. There's no single wire that will handle 500+ Amps of current.

    Some calculations to consider:

    8 kW hours on 12 Volts: 667 Amp hours. @ 50% DOD = 1333 Amp hours of battery minimum.

    8 kW hours on 48 Volts: 167 Amp hours. @ 50% DOD = 333 Amp hours of battery minimum.

    On a 48 Volt system you can easily set it up for 25% DOD, giving you an extra day of power if needed. The charging Amps will be lower, the current handling simpler, and the current balance more assured.

    Either get the total Watts and Watt hours way down or get the system Voltage way up, otherwise you will be way unhappy. I mean more so than you are now.
  • brandywinebrandywine Registered Users Posts: 15
    Re: Screw the Electric us off the grid..our story

    Thanks guys. Sorry, I didn't consider that word profanity....

    So, I bought this FREEDOM SW3000 after I had all my info for Phase I of the project.

    One big item is the Air conditioner...which can just run off the generator while we are home. I prob shouldn't have added it in along with some other stuff. Recalculating my excel spreadsheet now....

    SO back out these and we will only run these when the generator is on:
    Air Cond 2550 Whr/Day (510 watts)
    Microwave 155 WHr/day (1550 Watts)
    Washing Machine 448 WHr/Day (1066 Watts)

    My new total is: 4657 WattHr/Day (1783 Watts)
    That's 5ea of my 12v 182AmpHr batteries. These are RV deep cycle batteries from Napa (all we can afford right now).

    Is that more reasonable?
    We are running 100% off the generator when we are home and I'd really like to get a real refrigerator in the house and be able to function without it running all the time.

    Mickie & Travis
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Screw the Electric us off the grid..our story

    4657 Watt hours / 12 Volts = 388 Amp hours * 2 (for 50% DOD) = 776 Amp hours minimum.
    You will regret trying to supply that much power on a 12 Volt system.

    Remember: 12 Volt batteries can be wired in series to produce higher system Voltage. Same over-all Watt hour capacity, but with greatly reduced current meaning less power loss to heat and smaller wire sizes (less expensive) and easier charge current.

    At least consider a 24 Volt system (same power above with 388 Amp hours of battery) if not a 48 Volt. You could almost reach that power requirement on one string of those batteries @ 48 Volts (it would be 4368 Watt hours max). Lots of batteries in parallel becomes problematic in keeping the current flow even throughout all the batteries.

    I know; you already bought the 12 Volt inverter. :cry:
  • samuelsamuel Solar Expert Posts: 80 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story
    1. When we are running the generator...the inverter will be bypassed (i guess per the install guide). Will it still be charging the batteries even while we are using some power in the house?

    When the Xantrex has power from a generator it will both charge the batteries and also power the house/shed at the same time. On the Xantrex, you should be able to program the size of your generator so that if the AC load (from house/shed) + battery charger are greater than what the generator can supply it won't kill the generator - but with 8KW I don't think you'll have any issues.

    I'd like to add my 2¢ concerning 3000W inverters and 12V battery banks. But first a disclaimer - my set up is for a cabin (used 120 days/year) and the batteries reach full charge frequently from our solar (something to consider regarding "battery charge balancing"?). See the link in my signature for more...

    A quick summary: I have about 2 years experience with a 12V system (1540 Ah), one year experience with 810 W of solar, and 2 years with a Xantrex MS3000. The battery to solar ratio is a bit off (too much battery) but in winter in Upper Michigan it works out well for a 4-5 day stay followed by a 4-5 day absence. I recently did a check up on the batteries (specific gravity) and everything was still like new in that regard - I just added water and marked on the calendar when to recheck (again, this is a cabin used 120 days/year). With that, I'm not convinced that the number of parallel battery strings is automatically a bad thing. 12V also works well for adding in 12V lights - but I'm pretty sure that can also be achieved through some electrical know-how from a range of battery bank voltages. In my opinion a 3000W inverter is fine for a 12V battery bank, but I have noticed that the battery cables can get warm (but not hot) under a 1500-2000W load over time. The amount of heat will depend on how much shielding is on the wire - a bare copper bar will be room temperature by comparison. None-the-less my vote goes out for 24V if you can manage (the MS3000 had a 24V option, and I think the SW3000 is what replaced the MS after some sort of company merger/buyout whatcha-ma-call-it).
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story

    Suggest. That you read and understand the following links:

    It should also be said, that despite your aversion to the power company, consider this. Off grid PV (battery based) comes at bout twice the cost with half the efficiency of grid tie PV making your energy cost a out 4 times as much per kwh net/net out of the outlet.

    Over a comparitively short time, you WILL spend more on power. Also consider that in addition to you hardware and fuel costs up front, batteries have a fairly finite lifespan. The batteries that you have bought are not true Re batteries, and they will need to be replaced sooner or later,, my guess is sooner.

    If you have the grid available, even at some considerable price, one should consider what the economics are long term. If you are gnu to live there long term, the numbers might be startling.

    Grid power I s ~.10-.20 kwh. Battery based PV might run ~$1.00. At a conservative, 8 kwh/ day, the price difference might be ~$2200 per year.

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Screw the Electric us off the grid..our story

    The problems with large power capacity on 12 Volt systems:

    When sizing wire and fuses for current you should use the lowest possible system Voltage (usually 10.5 on a 12 Volt system) a the peak Watt output to determine the maximum potential Amps through the DC wiring. Normally you don't allow the Voltage to fall that low and you'll probably not use the maximum capacity of the inverter, but what you're supposed to do is: 3000 Watts / 10.5 Volts = 285 Amps. Keep in mind that 0000 wire (aka 4/0) can only handle about 300 Amps. You're pushing limits here that are better left unpushed. As for a 5 kW inverter, even at 12 Volt nominal that would draw more Amps than the wire can handle. This is not good or safe practice, and neither is paralleling wires to handle heavy current (each would have to have its own fuse rated for the wire, not the total inverter load).

    Paralleling batteries. You get the same problem with needing very large wires to handle the current potential, and each battery should have its own fuse. In addition, many connections mean many potential high resistance points which will not be equal across all strings. Some batteries will supply more load and receive more charge than others if you don't do it right (equal length cables for one thing) and keep an eye on things. When you do need a high Amp hour battery bank, using higher Amp hour batteries is better than paralleling many. Fewer cells to check on FLA's for one thing.

    And remember: no matter what the circuit, the longer the run the greater the Voltage drop and with a lower system Voltage that becomes a bigger problem than it would with higher Voltage.

    I didn't even mention the V-drop from heavy loading.

    But hey; no one has to listen to me. It's not my money you're spending.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story

    also recall she plans on running 2 of the 3kw inverters on 12v and not one. ouch!!!!

    now if it was just the refrigerator and a few other minor items being run you could probably get away with a 12v system, but what you propose is larger. if you can still tolerate the generator being run for a time during the day it could take the strain off of the batteries and lessen the overall requirements to allow for quite overnight usage. be careful in designing a battery bank as you don't want to use all of the wh of capacity it has as that'll kill the batteries. it is advisable to not go below 50% on the batteries to help preserve some lifetime in them and being cheaper batteries that lifespan is low to begin with.

    now i do admit you may be confused on the max wattage draw needed at one time and the total wh per day drawn and it may even be confusing me.

    don't sweat the wordage as i let it go, but i wanted you to not continue along that line as it is meant in a derogatory way.
  • simmtronsimmtron Solar Expert Posts: 87 ✭✭✭
    Re: Screw the Electric us off the grid..our story

    Another option Brandywine, is buying a propane fridge, I'm sure you can get propane delivery where you are? This also gives you the option of using a gas stove also which would reduce electricity needs. Our cost per month for a fridge/freezer and stove AND BBQ is about $30.
  • brandywinebrandywine Registered Users Posts: 15
    Re: Screw the Electric us off the grid..our story

    So, what is the xantrex 3000watts for then if it can only work off of 12v? Why would they make such a thing?

    I reordered our usage. Took the AC water pump off and put it on generator only since we are going to use a DC flojet water pump out of some water tanks we just got.

    I have attached my spreadsheet.

    Should I sell it, take my losses and get something else?
    Is there anything else that would work that isn't $3000 like that big machine that was recommended?

    We are going to start buying solar panels after we get this first part hooked up so we can move away from having to use the generator to charge the batteries.

    We will only run the generator when we are running specific loads that require it.

    Thanks. I am starting to understand a bit better but not all the way yet.

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Screw the Electric us off the grid..our story

    Why does Xantrex make a 12 Volt 3 kW inverter? Good question. Technically it can work - wired with 0000 wire (not too long). But to run things at that level consistently gets real ugly real fast. There's another company (which I loathe and will not mention by name) that makes a 10 kW 12 Volt inverter! You don't want to know the sordid details of that nightmare machine.

    Looks like your getting a handle on it. I'd suggest you check your refrigerator for real numbers. I've just tested a few and they are all over the place for power consumption. An "Energy Star" unit was one of the worst, using 50% more power than it claimed and having a very high start-up demand.

    A couple of other things: coffee pot. Learn to love propane. TV & satellite receiver; you can check the video settings on the TV and see if you can reduce its power, and run these two through a power strip so you can shut them off completely when not in use. Takes a bit more time to power up, but worth it. What have you got for lights? CFL? LED?

    Also don't forget that the inverter itself will use some power. My Outback consumes 20 Watts all the time: 480 Watt hours just to keep the power on.

    I think you may want to ditch the 12 Volt inverter in favour of a 24 or 48 Volt unit. Magnum makes a 4kW unit in 48 Volt, but to get the big inverters with the built-in charger you end up paying out large amounts of money. :cry:
  • samuelsamuel Solar Expert Posts: 80 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story

    A 3000W inverter and 12V battery bank can work for some people. Chances are there will be very few times when greater than 2000W is demanded from the batteries. I'm pretty sure the Xantrex can only run at 3000W for a dozen minutes or so. It can then run at a lower wattage (2600W?) indefinitely. Something to keep in mind.

    I biggest issue I see is regarding solar. Most chargers top off at 60-80 amps or so (well, at least the one's in my price range when I researched). On a sunny day I've seen 61 amps on an 12V 810W PV array. If you start getting into KW of PV panels, 12V will probably start to get pretty complicated. A good route to take may be to find out your ultimate goal for PV panels and go from there.

    I use 12V at a cabin, but for a permanent residence I would want at least 24V.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story

    with you reconfiguring the loads and being you already have the inverter, then maybe try to make a go of it with what you have. now 5 batteries is borderline with 1 day's worth of power consumption and may not give the cushioning for longer intervals, plus no expansion of loads. i know you wanted to do so much more, but don't we all sometimes.:confused: maybe use 6 batteries to allow for a touch more cushion and try to stay within the parameters you outlined in the pdf. this is pushing it a bit for a 12v system, but try it anyway. you will learn the abilities of the batteries, the inverter, pvs when they are employed, and even how to redistribute loads to be drawn at differing times in addition to conservation. if you mess up, it will be a learning experience as to what to change in the future. don't forget to run it past us first so you can minimize mistakes in your purchases.

    naturally you'll want the right sized wires, fuses, disconnects and electrical boxes, plus other miscellaneous items. it adds up quickly.
  • Shane JacksonShane Jackson Solar Expert Posts: 49
    Re: Screw the Electric us off the grid..our story


    New here but wanted to offer some advice. You might want to consider an Apollo Solar TSW4048. It is the best priced split phase inverter I have seen.

    As for panels, Sun Electric has laminates on sale right now for .50/watt. when you buy a pallet. You can get a pallet of the 30 - 185watt panels for $2775 + approx $250 shipping. The laminates will take some work to use as the need junction boxes added and either framing added or mounted using something to protect the panels.

    If you don't want to go thru the trouble involved with laminates, let me know. I might could help.

  • JcrabtreeJcrabtree Registered Users Posts: 22 ✭✭✭
    Re: Screw the Electric us off the grid..our story

    I'm in TN as well a little north of Nashville and ran into the same problems with codes - building this Oct, 2011 24x30ft cabin with loft - you gotta love the impact tax 2.00sf + 35cent sf permits.

    Welcome to the forums very helpful ppl here, been soaking info for about 5 months now.
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Screw the Electric us off the grid..our story

    The information given above is good and reflects many decades of experience.

    I have a 12V system. If I was starting all over, it'd be at least 24V but probably 48V. To change now would be very expensive.

    When we moved onto our place, it was in an RV with a little Honda generator. That was 1977 and I didn't know of this site then, otherwise my system would be different. Icarus!! Where were you when I needed you!?

    First it was "add a few batteries" to last longer w/o running the generator. Then, found a deal on a 12V inverter which meant we could run the generator less. Then more batteries for less gen time. After a few years, it was only a matter of adding solar panels to decrease the gen time even more. More batteries. More solar. Bigger generators. More inverters. The system and my experience have both evolved much in 30 years. Now the gen typically runs only after a couple of days with no sun. My panels total a little less than 3KW. The battery bank is a dozen US2200s.

    And we don't live like hermits.

    Now my suggestions: as was said, put all your electronics/entertainment on a switch and turn it off when it's not being used.

    Microwave from an inverter isn't a problem, it doesn't run long and will cause more wear/tear on the gen powering the microwave that way for short bursts. Or "letting it run" just because you wanted to use the microwave for 2 minutes.

    Use propane for any heating you can, it's harder if you can't get it delivered but still better to carry it than use valuable electricity to heat water, coffee, or cook.

    My system uses three inverters -- 2500w, 2800w & 2800w. All 12V of course.

    One 2800 powers lights and entertainment and does not have a generator input. When the gen starts, the inverter would transfer power to the load and commence charging the batteries. Transferring sensitive electronics to the generator and back can make little power glitches that can cause problems, including your TV and sat "winking" off and resetting at the change. These things are powered from my inverter no matter if the generator is running or not. I also run a Sanyo min-split air conditioner from this inverter.

    The other 2800 powers fridge, washer, (propane) dryer, microwave, compactor, disposal and a few lights and other small appliances. No problem running the washer and dryer together, with the fridge making ice, and heating with the microwave. When the generator is running, this inverter is charging 100a.

    The 2500 inverter powers a jet pump (from a cistern to two bladder tanks) and a deep (350') submersible Grundfos SQflex pump for filling that cistern. Both can run at the same time. This inverter charges 100a when the gen is on.

    There is also a 12V Shurflo water pump as a backup for the water pressure.

    Long post to say "yes, you can base your system on 12V". You may decide against it and write off the money spent on that inverter before you spend more for 12V, or plan your wiring and circuits so that you could upgrade to a higher voltage later on. For instance, having large cables for 12V will only benefit you with higher voltages.

  • samuelsamuel Solar Expert Posts: 80 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story


    This might be worthy of a new thread. But I'm curious. You mentioned that:
    My panels total a little less than 3KW.

    As another person who has gone the 12V route and then somehow found themselves with a system that became much more than originally planned - how do you handle the 200 or so amps of PV panel charging current?
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Screw the Electric us off the grid..our story
    samuel wrote: »
    As another person who has gone the 12V route and then somehow found themselves with a system that became much more than originally planned - how do you handle the 200 or so amps of PV panel charging current?

    I have four charge controllers all with individual cables to the batteries. From what I've gleaned at this site, a 100 amp charge rate is acceptable for my battery bank, as is the 220 amp rate when the generator is running (I didn't mention an automotive charger that supplies 20 amps as soon as the gen starts, it's used to give a "ballast" to the gen so the two inverters will "lock on" to the gen and start charging).

    I never have seen 200 amps from the panels, typically something a little over 100 amps. Nothing I've learned here indicates that 100 amps from my array is a abnormal. (The label ratings for my array is actually 2710 watts).

    I use two Outback MX60s, one Outback FM60, and one Xantrex C60. The C60 doesn't have a digital readout so I can only monitor the current from the Outbacks. I do have the digital face for the Xantrex but it is installed on a C35 in our RV. I have in the past put it on the C60 to verify proper operation and get a feel for charging current, typically 10 amps as it's got only three old Siemens 100watt panels.

    Since I'm not positive I understood your question I also am unsure I've answered it.

  • samuelsamuel Solar Expert Posts: 80 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story


    Thanks for the reply. I think that answers my question. I have a C60 charging at 12V on panels with a labeled rating of 810W and have seen 61 amps (though 40-ish is more common). I didn't know if two chargers in parallel would work properly, or if they would interfere with one another. I'm trying to learn if it is possible to add another C60 and more panels to the existing set up. Not that I would, just trying to find out if I could ;)

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Screw the Electric us off the grid..our story

    side question for you.
    have you ever considered going the route of mppt? i know they cost more, but they can deliver a good extra kick with the same pvs in place.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Screw the Electric us off the grid..our story

    I have a question for the original poster. how has the system performed since it was completed?
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