xantrex xw 4024 and generator

hillbilly1
hillbilly1 Registered Users Posts: 5 ✭
in Off Grid Solar & Battery Systems #1
I'm thinking of getting one, If used completely off grid, how long will it take to charge the batteries? remote start generator suggestions? I have more questions as to will this push a 12000 btu window ac unit? I live in MS so air conditioning is needed. Its my understanding this unit can run just off the generator, and i can add solar panals and grid power later. Budget is somewhat limited now. How big a generator will i need? How many batteries to run a 1600 square foot house 3 bedroom? I know thats alot of questions but any help would be appreciated, as right now i have no choice but to off grid, the power company wants 12 grand to pull power to me. as more folks move in it will get closer and cheaper. But i like the idea of no bill in the future!!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: xantrex xw 4024 and generator

    The $12,000 might still be the cheaper, long term solution. Don't some utilities give "kickbacks" if they get other customers down the line?

    It is all in the loads. Are you willing to get a "inverter" type mini-split A/C unit? They have very "off grid inverter" friendly energy profiles (usually no surge current, and they crank down the power usage as you cut back on BTU output--Instead of just cycling on and off).

    Otherwise, some people live very nicely on 2-3.3 kWH per day, and others need 7-8 kWH per day (or more). Very different system designs and very different in installation and maintenance costs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • hillbilly1
    hillbilly1 Registered Users Posts: 5 ✭
    #3
    Re: xantrex xw 4024 and generator

    When more people buy the lots closer, the power will come closer and when it gets to about a grand i will have it pulled. but in the meantime i have to buy a generator to build the house, and i noticed the Xantrex xw 4024 will remote start a generator to charge the batteries. Meaning i could add the solar panels as i get the funds. In other words i can run just off the Generator for awhile.

    I have a neighbor who is running his house off just a generator, no inverters untill the power comes, but he said the fuel cost is expensive, hes running on propane. I'm new to this, so ive been studying it some. The xw 4024 seems to be a answer. Am i wrong? it runs on 24 volt, but i can find nothing on how long it will take to charge the batteries, on an average house. It's my understanding i can add solar, and hydro later. I have a potential hydro power site. But it will require money to build. Im trying to get by till the power comes, and i can build the hydro system.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #4
    Re: xantrex xw 4024 and generator

    All your questions depend on your daily energy (kWh) consumption and peak load (normal loads plus things like well pump, etc.). IMHO, a single XW4024 is going to be a bit on the light side for a 1,600 square ft home. It'll run a 12,000 BTU AC unit with no problem - that's only 7 amps. But it has to carry your other normal loads at the same time. The XW, like our SW's, have gen support so they will bring the generator online and use both gen and battery power to run heavy loads. But standby generator power costs roughly 80 cents/kWh when you live off-grid so it would be prudent to take measures right up front that keep the generator from running.

    You'll spend a lot more than $12,000 on dual inverters, a 2,000 ah battery bank and a generator.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: xantrex xw 4024 and generator

    Welcome to the forum

    "How long will it take to charge the batteries?" is not as specific a question as you might think. How much battery drawn down to what SOC and recharged to what level?

    This is basically off-grid (for now) so the whole thing depends on loads. Without knowing them, there are no answers to be had. Still we try to answer the questions. :D
    The XW4024 has a a whopping 150 Amp charger which can bring batteries up pretty fast. However there is such a thing as too fast. The best thing to do would be to try an mimic off-grid with panels. In this case you want 400 Amp hours of battery minimum (so it will work for grid-tie later) and limit the charge current to the 13% which is usually the practical maximum for flooded cells and PV's (which we are trying to mimic in this example). If you use AGM batteries you can push the rate higher.

    But let's say for the moment you go with the inexpensive golf cart batteries @ 220 Amp hours 6 Volts. Eight will get you 440 Amp hours at 24 Volts. Peak charging current set around 57 Amps. Limit to 25% DOD gives you 110 Amp hours @ 24 Volts or roughly 2.6 kW hours of power per day. Is that enough? Unfortunately the recharging isn't as simple as 57 Amps for 1.9 hours = 110 Amp hours. It will take longer than that, because the current drops off as the Voltage comes up and the last of the charging - the Absorb stage - is a notorious fuel waster for generators due to its low current/high Voltage/long time aspect. But on the whole most of us off-gridders who follow the guidelines above will get the charging complete in <4 hours.

    Now if this were going to be strictly off-grid with no future grid-tie I'd recommend against the XW inverter; no sense buying GT ability if it isn't needed, and Xantrex brand is not without issues.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    Re: xantrex xw 4024 and generator

    It all really depends on loads... You can size a generator to recharge you battery bank in 5 hours of run time (roughly). However, will that be a 3kW genset or a 15 kW genset.

    Lets say you want 10 kWH per day (300 kWH per month). That is actually is quite a low level of power usage (especially if you have A/C requirements). The "typical" US home uses 1,000 kWH per month (~33kWH per day).

    So--For a normal setup we recommend 1-3 days of no sun, and 50% maximum discharge for long battery life (this is for a solar system, but we can use generator only and see what happens:
    • 10,000 WH per day * 1/0.85 inverter eff * 2 days no sun * 1/0.50 max discharge * 1/24 volt battery bank = 1,960 AH @ 24 volt battery bank

    So--The first look at this, we would recommend a 5% to 13% rate of charge--And 10% of 1,960 AH is 196 amps charging... That is really a heavy current and I would suggest a 48 volt battery bank to cut the current by 1/2 (still same price for batteries, but less for copper wiring costs):
    • 10,000 WH per day * 1/0.85 inverter eff * 2 days no sun * 1/0.50 max discharge * 1/48 volt battery bank = 980 AH @ 48 volt battery bank

    Next, what charging current/power would I recommend a 10%-13% rate of charge (you could go as high as 25%--but that brings other issues). A good quality Power Factor Corrected battery charger (like the XW family would be):
    • 980 AH * 0.13 rate of charge = 127.4 Amps charging current

    An XW6048 inverter/charger has a maximum charging current rating of 100 Amps into the 48 volt battery bank--So "close enough" for government work. Running the numbers:
    • 100 Amps * 59 volts charging * 1.0 PF * 1/0.85 charger eff = 6,941 Watts input power max charging

    So, you would be looking at a 7kW to 15kW genset for "optimum charging" through the XW.

    We are recharging the 10kWH per day from the battery bank:
    • 10,000 WH * 1/48 volts * 1/100 amp charging = 2.08 hours

    But roughly, you will need a "bulk" and absorb cycle"--So you are looking at around 4-5 hours of daily charging (or 8-10 hours every other day) of charging.

    Say the genset uses ~1 gallon per hour for charging (and running other loads), a 10kWH per day load through a battery bank would be around 4-5 gallons per day.

    The above are really rough guesses, and a bit on the "conservative side" (hopefully you will do better)--But it is a line in the sand.

    Now--there are a lot more people here with more off grid/generator experience than I (me-- ~none)--So they may be able to better able to size a system for you and estimate the costs.

    Nominally, I would suggest a much smaller system that supplies power for lights, radio, tv, computer, water pumps, etc... And when you need more power (A/C, shop tools, etc.), that is when I would fire up the genset.

    You may also want two (or more) gensets... A smaller one (like a Honda eu2000i or similar Yamaha inverter generator) for average loads--And fire up the big iron for A/C and tools.

    Again--it all depends on your power needs.

    You might start with a Honda eu2000i (or similar)--small quiet, fairly fuel efficient at lower loads--and a second 6-7 kW genset for the tools--And see what your power/fuel costs are.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • hillbilly1
    hillbilly1 Registered Users Posts: 5 ✭
    #7
    Re: xantrex xw 4024 and generator

    Thanx, glad to be here, as this looks like a good place to get educated. Let me start over and given my topic, what would u suggest for a system if the xw is not the answer? I'm all ears, especially if its gonna save me some money. One of the things i liked about the XW 4024 was that it seemed to have "Brain" sometimes i may be at work and i am not sure of my wife being able to manage this. What other systems or setups would you suggest for a generator based inverter system with remote start capabilities? batteries? 12 24 0r 48 Voltage? Gas, Diesel, or LP? yada yada. LOL!!
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #8
    Re: xantrex xw 4024 and generator
    BB. wrote: »
    You might start with a Honda eu2000i (or similar)--small quiet, fairly fuel efficient at lower loads--and a second 6-7 kW genset for the tools

    A Xantrex XW will run just about any power tool you can imagine with no problem if you have enough batteries on it. But it requires split phase input so an inverter gen is a bad choice, especially for auto-start because the Honda EU's have a manual choke. The XW4024 is a top notch unit for off-grid - IF you need split phase power. If you don't, then get an Outback unit instead.

    Something like a Honda EM-SX series works good with a XW inverter because it puts out split phase power, has an auto-choke for auto-start setups, and only requires tapping into the key switch circuit with the GSM to make it a three wire auto-start unit.

    However, I don't recommend gasoline for off-grid because you're paying road tax on the fuel. A Yanmar diesel or (if cost is no object) a Generac EcoGen is a better choice.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: xantrex xw 4024 and generator
    hillbilly1 wrote: »
    Thanx, glad to be here, as this looks like a good place to get educated. Let me start over and given my topic, what would u suggest for a system if the xw is not the answer? I'm all ears, especially if its gonna save me some money. One of the things i liked about the XW 4024 was that it seemed to have "Brain" sometimes i may be at work and i am not sure of my wife being able to manage this. What other systems or setups would you suggest for a generator based inverter system with remote start capabilities? batteries? 12 24 0r 48 Voltage? Gas, Diesel, or LP? yada yada. LOL!!

    Back to the #1 off-grid question: how much power do you need to supply? This includes maximum total Watts at any given time, daily Watt hours, and whether or not you need 240 VAC.
    Really, everything hinges on that. Otherwise you end up with a system that either doesn't keep the lights on or costs too much $.
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  • hillbilly1
    hillbilly1 Registered Users Posts: 5 ✭
    #10
    Re: xantrex xw 4024 and generator

    I have not added up each item in my present house as far as watts, but i guess im the average american, will run a 42inch lcd tv, lights occasionaly, microwave 2 minutes a day, my stove will be lp, as will my on demand water heater. In Mississippi u need a window unit 4 months of the year, mine is 12,000 btu.

    I have a computer, printer, washing machine that gets used pretty regular" 7 year old daughter, who changes clothes alot" fridge with freezer built in, I will have a Ram pump installed so my water will require no well pump, but i may need a booster pump. Will dry clothes on clothesline.

    Far as tools go, very rarely, i can fire up the gen for that. The ac seems to be the kicker, u just cant live without it in this humidity.Most of the time its just the tv on, the fridge running and the ac during the summer, I have a woodstove. What other remote start generator options are out there? I didn't mean i was gonna buy a inverter generator, What i want is a system that will start the generator when the batteries get low, so i don't have to constantly watch the batteries. Propane generators seem to be expensive and use alot of fuel. Champion makes a 9200 watt with remote start capabilities. would be nice not to have to haul diesel or gas, "Propane truck will come to the house" . But i'm all ears to any suggestions on a system if the xw is not needed for off grid use. What system would u suggest.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #11
    Re: xantrex xw 4024 and generator
    hillbilly1 wrote: »
    Champion makes a 9200 watt with remote start capabilities. would be nice not to have to haul diesel or gas, "Propane truck will come to the house" . But i'm all ears to any suggestions on a system if the xw is not needed for off grid use. What system would u suggest.

    Champion generators are very good and they have excellent customer support. I have a 3 kW Champion remote start unit for backup, plus we use it for our RV. It has been a top notch generator.

    I didn't see anything in your list that requires 120/240 volt power. So you could go with an Outback inverter. The only problem with Outback is their auto gen starting with an Atkinson controller sucks eggs thru a straw. They work fine with a two-wire start just using the Aux port. But if you three or four wire it's a pain, and a Champion needs a three wire start system.

    And then you're digging into another problem with the 7,200 watt (9,200 watt surge) Champion - it's a 240 volt generator. So if you get an Outback inverter that means buying an autotransformer to balance the generator legs because the Outback is 120 volt input.
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  • hillbilly1
    hillbilly1 Registered Users Posts: 5 ✭
    #12
    Re: xantrex xw 4024 and generator

    suggestions on a system then from a to z?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #13
    Re: xantrex xw 4024 and generator
    hillbilly1 wrote: »
    I have a computer, printer, washing machine that gets used pretty regular" 7 year old daughter, who changes clothes alot" fridge with freezer built in, I will have a Ram pump installed so my water will require no well pump, but i may need a booster pump. Will dry clothes on clothesline.

    These are all pretty low power devices. Except for the fridge (possibly).

    A Kill-a-Watt meter running on them (a K-a-W meter on each appliance for a few days at a time--log the data) will give you the kWH per day each draws (on average). And, you could probably run everything listed above on a 3.3 kWH per day system.

    ASSUMING, you purchase very energy efficient appliances (fridge, laptop vs desktop computer) and turns things off when not in use printers, DVR's, Sat Boxes, etc.). The kill-a-watt meter will show you where your "problem loads" are. Note, many times it is not the microwave running 1,500 watts for 15 minutes (0.375 kWH per day), but the smaller loads that run all the time such as a desktop computer system (0.200 kwatts * 24 hours per day = 4.8 kWH per day).

    The A/C is always an issue--But a well insulated home with appropriate shading/inset to a hill/etc. Perhaps only cooling a few rooms during the day (office, family room)--The new Mini-Split A/C systems have some very happy users here.

    ChrisOlson (and others here) bring up the details of selecting components/generators/etc. so they play well together. But without knowing your power usage, it is difficult to size the system with the correct devices.

    Run the Kill-a-Watt meter at your present home to get some data... Or, run a (rented, borrowed, or try a Honda eu2000i--many folks have used them for the first few months off-grid for running there home--basically one 13 amp 120 VAC outlet--can run much of your home with right hardware) genset for a few weeks with a few kill-a-watt type meters and then you will have a great starting point for designing the "Optimum" off grid system.

    Power usage is a highly personal choice... I think I am doing great at 200-300 kWH per month (natural gas for all heating/cooking/etc.) with a 70 year old suburban home and family of four. However, others here will use 1/3rd of that amount or less--thinking I am an energy hog.

    Another way of looking at how to trade off buying expensive Fridge/AC/Laptop Computer/etc. appliances with low power usage is to plan on your off grid power to cost you around $1-$2+ per kWH.

    If you can use a laptop computer at 0.4 kWH per day vs a desktop at 4.8kWH per day (yes, big extreme, and probably not fair--but an extreme comparison between a full blown server running 24x7 and a smaller desktop running 10 hour per day configure to "sleep" when not used):
    • (4.8 - 0.4)kWH * $1.50 per kWH * 365 days per year = $2,409 per year in savings

    In a year or two--you have easily justified replacing a large desktop system with a smaller laptop and watching your power usage (of course, this depends on your computing needs).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #14
    Re: xantrex xw 4024 and generator

    Generator/battery/inverter with solar later is a traditional way to homestead. Don't do it!!! If you commission the system with the solar panels you will get 30% federal tax credits on everything but the generator. 30% of the conduit, wires, fuses, batteries, inverter, etc is enough to pay for the panels, combiner and charge controller.

    Also, $12,000 is cheap for a grid hookup. You will spend at least that on a system of the size you are contemplating.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #15
    Re: xantrex xw 4024 and generator
    hillbilly1 wrote: »
    suggestions on a system then from a to z?

    If it were me I'd go with the XW inverter, 1,000 ah of batteries, 1 kW of solar and a Generac EcoGen.

    It will cost more than the $12,000 it costs to get grid power, but it appears one of your goals is to be self-sufficient and that makes the money spent on off-grid equipment worth every dime. It doesn't always boil down to economics.

    I have my reasons for picking these things - the XW inverter is split phase and it has dual AC inputs. You said you might eventually get grid power. When and if you do it will require no re-wiring in the home - simply hook the grid up to the AC input on the inverter.

    1,000 ah worth of batteries at 24 volt will carry the loads you mentioned with no problem for a day, and the reason I would put 1 kW of solar in right off the bat is because during the day with the AC unit running the solar will just about power the AC unit without having to run the gen. At the very worst, the solar will keep the gen hours down with that AC unit going. You will pay for the solar in the first year in fuel savings.

    The Generac EcoGen - it is designed for off-grid use. It is a medium speed generator fueled with LP and is two wire auto-start. I prefer LP for off-grid over even diesel because LP gas can be stored indefinitely and it never goes bad. You said some of your things like water heating and cooking will be LP. So LP gas is already on the homestead - just put in a 500 gallon tank and run the generator on it too.

    A generator consumes more LP gas in gal/hr than a diesel, but that's because LP gas has less BTU content/gallon. If you pencil it out, your cost/BTU is probably going to be very close to the same with diesel or LP, but the diesel runs at higher thermal efficiency than the LP engine so it will still run cheaper/kWh based on fuel cost alone. But the fuel is only one cost of operating a standby generator, and I believe that with LP already on the premises that it's the better choice in this case.

    As I said earlier, the XW has gen support, meaning it can combine its output with the generator. With a 4024 and a 6 kW EcoGen combined you have 10 kW of power available to run even the heaviest loads. You could power even an electric range with that setup. The XW also has load management that you can program, so if the loads exceed what your battery bank is comfortable with it will bring the generator online automatically to help out with the load, then shut it off when the load drops to a more comfortable level again. I mention all this because you said you might be gone and your wife is there alone. And she probably doesn't want to interact with the system, so it has to "just work". And this is the way our off-grid system is set up - it "just works" and takes care of itself and all we do is look at meters sometimes to see how it's doing. We also run a window AC unit during hot days in the summer so I understand that requirement very well.
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