off grid generator/battery bank

Howdy,
I'm planning an off grid full time home in northern NY. It will have a small electric footprint as it will be a single person home and will be fitted with propane or alternative appliances as much as possible. Still I have need of a robust electrical system for 240v well pump as well as power tools etc. As I don't live in one of the greatest solar areas I am not overly interested in Solar panels at this point, although that may come later after all the major electric tool use is compete.

My plan is to have a generator/battery bank and run power through a home inverter and I would like to get any ideas/advice this forum can provide.

My thought is that with the right system I would be able run the generator only a couple hours each day to charge the bank. I plan to acquire a diesel generator at some point although for the moment I am running a honda gen/inv and also have a gas powered 7000W unit. I am unsure of the pros and cons of 12,24 or 48 volt battery systems but suspect that I would be happier several smaller batteries than one or two monsters.

I know this is a pretty broad request but any advice you can provide would be greatly appreciated.

Thanks

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: off grid generator/battery bank

    Welcome to the forum IC,

    Basically, it is all about your loads. Two major numbers you need... One is the peak watts (starting surge and short term heaviest loads) and long term energy use (average Watts * Hours per day = Watt*Hours/KWatt*Hours per day).

    It is virtually impossible to design a cost effective system without knowing some basic numbers. We can do some rules of thumb designs along the lines of:

    1,000 WH (1kWH) per day (30 kWH per month)--Cabin with lighting, computer, charging cell phone, small water pressure pump, radio, etc.
    3,300 WH (3.3 kWH) per day (100 kWH per month)--Very efficient off grid home; above + full size energy star refrigerator+washing machine+well pump
    10 kWH per day--As above, (300 kWH per month) normal home with all normal appliances, using natural gas/propane/wood for heating/cooking/hot water, some electric cooking (oven, etc.).
    33 kWH per day (1,000 kWH per month)--Average north American home power usage (no conservation to speak of). More electric heating/hot water.
    100 kWH per day (3,000 kWH per month)--Full A/C in southern US, electric hot water, electric heating in northern climates.

    Energy use is a highly personal set of choices. Adding a refrigerator, lots of computer (desktop, or heavily used laptop+laser printer+network+Sat/Cable modem), deep well and lots of irrigation, shop tools (air compressor) all add lots of loads to your off grid power system and are very expensive to support with battery banks+AC inverters.

    A 1 kWH per day system is small/cheap.
    A 3.3 kWH per day system is good sized ($20,000 +/-)
    A 10 kWH per day system--About as large as a normal person can afford for off grid solar.

    Solar panels are historically "cheap" at this point... And if you have off grid needs, they are usually worth the expense+effort vs just throwing a genset at the problem.

    At this point, just guessing, you might want to look at a 1 kWH per day battery+AC inverter system to supply your "over night" and constant on loads (lighting, radio, laptop computer, cell phone charging, water pump to pressurize home from shallow well/cistern) and use a genset to run your larger loads and recharge the battery bank during the day.

    Something like a MorningStar 300 Watt TSW inverter + 2 to 4x 6 volt @ 220 AH "golf cart" type batteries + 20-45 Amp AC Battery charger + a Honda eu2000i would work very well for such a system... Later on, you can add solar panels and reduce the genset run time.

    And run the generator when you need more power (tools, shop, cooking, doing wash, filling cistern). Perhaps, you can even look at using a 3-7kWatt genset for your larger loads.

    For a genset, generally, they are most efficient when running at ~50% to 80% of rated loads. If you have 3.5 kWatts of loads (electric water heater, well pump+irrigation), a 7 kWatt genset will run them efficiently (~0.5 to 1.0 gallon of fuel per hour).

    But, if your loads (and your battery bank system is small), you are looking at 500-1,000 watts of power to recharge the battery bank and run some of the smaller loads. A Honda eu2000i will supply ~400 watts to 1,600 Watts for ~9+ hours to 4 hours (depending on loads) on ~1.1 gallons of gasoline.... Or 1/4 to 1/10th the amount of fuel a 7 kWatt genset will drink.

    There are a newer class of off grid inverter-chargers with "generator support" function... These inverters will blend battery power+generator power seamlessly. They will supply AC power from battery (no generator running), charge the batteries from genset, and even supply heavy loads with generator+battery power (make a small generator look larger).

    Really nice... you program them to draw ~1.3 kWatts from the Honda eu2000i, and the AC loads can range from 0-2 kWatts or more (depending on inverter model)... And the generator will never "see" more than 1.3 kWatt load. You just need to start the genset when you know you will have large/continuous loads and/or battery bank needs recharging.

    Lots of options--But need to know more about your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ironcross
    ironcross Registered Users Posts: 3
    Re: off grid generator/battery bank

    Thats some good info. I came to the right place.

    I suspect I'm gonna fall right between the 1KWH/day and 3.3KWH/day figures.

    I have a deep (400') well with an efficient grundfos SQE pump (good for varying power but 240 requirement)
    and a large chest freezer but otherwise have propane refrigeration, cooking, laundry, and back-up heating.

    I also have led lighting and minimal electric appliances but certainly will have cell phone charging, computer
    and television usage as well.

    I fully intend to utilize some solar panels but for the time being that may just be some smaller battery tending
    panels to be expanded later on.

    shop tools are a necessity as well which is why I'm planning for a larger diesel generator so that when loads
    are heavy I will use that vs stored energy.

    I'll check out the morningstar 300. Can you give me an example of the off grid inverter-chargers with
    "generator support" functions you mentioned so I can do some research there as well?
  • Alaska Man
    Alaska Man Solar Expert Posts: 252 ✭✭
    Re: off grid generator/battery bank

    You can plan on running your generator about 6-8 hours to fully charge most battery banks. My charger is a 150Amp Xentrex charger

    This is where Solar Panels will really save you in fuel use/generator run time.

    I lived for a couple of years with just my batteries and generator, running very small loads and I still had to charge once a day sometimes twice and to fully charge you are talking at least half a day.

    You are going to want to look at solar once you start figuring how much money you're burning up everyday.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: off grid generator/battery bank

    I used to live in NY. It would not be my first choice location for a solar installation.

    You can design a system to run off solar on any sunny day and run the gen to push the charge up on days the sun does not co-operate. This may be more often than you like; depending on where you are you get the choice of "cloud capital of the world" and daily snowfall measured in feet.
  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    Re: off grid generator/battery bank

    Yes, your premise of running the gen "a couple of hours a day" has a slight flaw. Lead acid batterys cant be fast charged, and take hours to charge as AM said. And thats only bulk. To get the battery life, a full and complete absorbion period is also required which takes yet more hours, and ony draw tiny amounts of current. Thats where solar comes in.

    I gather you know engines, and thats lead you to this plan. Do you have access to grid? Solar as Bill said is pretty cheap and, certainly cheaper long term when compared to gensets plus fuel. But not as cheap as grid.

    Assuming your no-solar plan could be made to work, what i would be doing is calculating the cost of the kWh, so you know what your getting into. Factor in routine engine rebuilds, and other maintenance costs.

    If this is still the route you want to go, (and its not RE at all i guess), then there is only one battery that will do it: Lithium Iron Phosphate. But be prepared for a large learning curve.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    Re: off grid generator/battery bank

    I can tell you a friend JUST did the same thing you are talking about. And he was sure to "properly" charge the batteries (i.e. absorb, etc)
    His plan was to buy the panels in a year (fund issues).

    However, within 1 month of the install he was buying Solar Panels. The fuel cost was prohibitive.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • ironcross
    ironcross Registered Users Posts: 3
    Re: off grid generator/battery bank

    sounds like more generator usage than I was expecting. I'm in northern NY where solar isn't great and I'm over 1/2 mile to grid power so I was thinking that the cost of getting power run out there would be prohibitive... probably as much or more than a solar system and certainly more than the cost of several gen sets.

    Assuming I could take advantage of tax breaks for using alternate power I would be all over solar but since I'm not on the grid that isn't going to work out for me as far as I know.

    Thanks for all the comments.
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: off grid generator/battery bank

    If I were in your shoes.

    Propane fuel generator w/240V output for well pump (fuel keeps forever) (unless it's too cold in winter to vaporize to gas)
    at least a 24V battery bank, could be as simple as 2, 90ah deep cycle batteries in series. (or 4, 6v golf cart batteries in series)
    And a couple solar panels to reduce the generator time.

    The temptation to use 12V, with all the nice 12V toys, is great, but if your power demands grow beyond 12V, 200ah, you are into major beefy $$ batteries, and it's not likely to run the well pump.

    Another possibility, but you would be a trail-blazer here, would be Lithium Batteries. Several types of chemistrys, with different pros & cons.

    One thought is about 2Kw inverter genset you can afford to run for 4 hours to charge batteries slowly.

    Be sure the charger you choose, has a decent Power Factor.

    Schnider/Xantrex has 24V & 48V off-grid inverters with integral chargers, and native 240V split phase USA standard. And they have working generator support (works for me anyway). You will need a System Control Panel (SCP) or ComBox to program the inverter settings.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: off grid generator/battery bank
    ironcross wrote: »
    Assuming I could take advantage of tax breaks for using alternate power I would be all over solar but since I'm not on the grid that isn't going to work out for me as far as I know.

    That's nonsense. The 30% federal tax credit is yours for the asking. The credit is on everything but the generator. Batteries, meters, inverters, panels, mounts, etc. Even on labor. If you build the system without solar panels and add them later, you only get the credit on the panels.
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Alaska Man
    Alaska Man Solar Expert Posts: 252 ✭✭
    Re: off grid generator/battery bank

    AGM batteries can take much higher charging amps thus reducing generator run time, but they are not cheap and they are persnickety. Make sure you read all there is to about Batteries, Charging, Amp Hours etc. For me the education of just how much power storage you actually can use for the amount of money you just spent was a shocker, kick in the ding, ding really.

    You buy thousands of Amp Hours that costs you thousands and thousands of dollars then find out you can only use a couple hundred............... Was not a happy day I'm here to tell ya.
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    Re: off grid generator/battery bank

    I don't know where in Northern NY you live, but my camp is north of you (and north of Ottawa). We get along just fine with solar at our off-grid camp. Granted, it is part-time and seasonal. However, one of my neighbours on the lake is a year-round resident and he gets by with a 2KW PV array.

    I lived in Rome, NY for 5 years. I don't think that the insolation was much different from what I'm seeing up here.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: off grid generator/battery bank

    The freezer--Can drive you to a 1,200 to 1,500 watt AC inverter (or at least 1,000 watt minimum). Compressors can take quite a bit of current to start.

    Regarding generators and inverters:

    Choosing a good generator
    genset alternator failure (and if your generator is not generating AC? What to look for/do--Thread started by "Unicornio" from Spain)
    Demonstration of Generator Support

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • medic149
    medic149 Registered Users Posts: 4
    ironcross, wondering how you made out.  

    We just bought an off-grid 320 sq/ft cabin, north west of Rome, NY.  Looking to eventually go solar, but figured the first year or two I will use 24V of battery bank and my 2 Honda 2200i's in parallel to charge the battery bank and for extra power if needed.

    Curious what batteries you went with and how your system was setup.

    Andy
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Medic149,

    IronCross has not been back here for ~6+ years... Probably not going to hear much (if anything) from him.

    Please feel free to start a new discussion (thread) and tell us more about your energy needs, location, seasonal usage, requirements, expectations...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset