Hi everybody. I have been lurking for a long time and just started building. I may end up moving in on a permanent basis much sooner than anticipated. Therefore I need power! We are pretty remote so we have no choice but to be off grid. Right now we are running a 2KW Champion inverter generator. My plan is to build a battery bank of Trojan T-105's with a 3KW Inverter. I plan on topping off the battery bank every day with the generator because of the limited solar availability, we are in Northern Minnesota.
How do I figure how many watts are delivered by the bank? Will 6 batteries provide enough power for a few hours every night or will I need 8 (2-3KW)?
What do I need, 6 batteries, charge controller, inverter, generator. Am I missing anything?
Now, I know to use the calculator to figure out usage and needs. But, what I need to do is change our lifestyle to fit our system rather than size our system to fit our lifestyle. We plan on using things like LED lightbulbs, charging laptops and cell phones at work/school. One, MAYBE two TV's, new super efficient fridge, gas stove, wood heat, laundry at laundromat.
I know this system may not be ideal but it is what I have to work with. My sister lives next door and they run everything off a 5KW LOUD generator everyday! We are NOT doing that!
Thanks in advance.
In order to the size the battery bank without making the number one error* of first time off gridders you need to firmly establish what your power requirements are or will be. And if you are like many, like myself and my wife, your use will grow a bit over time.
* #1 error is lack of battery capacity, followed by lack of means to recharge the daily withdrawl. Much like many folks have problems emptying and refilling bank accounts.
So, until you know what the daily average daily watt-hour consumption is or will be you and anyone else will be guessing. I could could say, well twelve 6 volt GC2's (24 VDC system) work well for us. But that's with a propane refrigerator and that's out usage pattern.
Electric refrigerators still are going to be the largest single consumer of electrical power. In our case a rough estimate is that a modern electric fridge around 18 cu ft (with freezer) would about double our electric use. That requires some thought as to what is best for each and every individual/family. I don't like using LP but at the time we made the choice it seemed the most friendly to our initial budget.
I would do as much as I could to minimize the generator use. Depending on a generator is less than ideal.
Mtn Don, thanks it's an honor to finally get your advice on my project! I just read the other thread about a low budget setup. I agree about the guessing, but I cannot really accurately estimate my usage. Like I said, we need to change our lifestyle rather than buy a system that costs $10K just so we can have four tv's and game systems running at the same time! (I have four kids at home. I am trying to get them to unplug)
I guess my main problem is that I don't know how to calculate KW/Amp Hours etc into real usage. Will 6 batteries be enough to power a 3KW inverter? How much will it drain every night with a tv a few lights (CFL or LED), and misc chargers, direct tv receivers and/or dvd players , etc.
I would rather have solar, but my budget in the near future won't allow them. My Champion inverter generator is very fuel efficient, so I would mind running it a few hours a day to top off the battery bank until I can add some panels next year.
I am considering a propane fridge but also looked at a couple at Home Depot that claim less power usage than a 60W light bulb.
BTW, my wife is from Portales, NM. We met when I was staioned at Cannon AFB in '95. We go back once a year or so but never get to make it to the pretty parts of the state!
One more thing:
We will have a well, but will use the AC pump only to fill a 275 Gallon tank. From there we have a 3GPM DC ShurFlo pump to supply water. This may be on a stand alone battery or tied in the the system. Probably stand alone for awhile since I just bought a battery for it.
Start with making a list of everything that will be powered, plus a realistic time for each.
Have you had a look at this Off Grid calc? (http://countryplans.com/smf/index.php?topic=8192.0). It's not perfect but can help with doing the math to determine the battery capacity required. It needs honest input though. The power labels on items are useful though some items use less than the label in a day to day normal use. A Kill-A-Watt meter can help estimating by measuring actual use of items over a time period.
Have a look at it, it should help in your assessment. You need to scroll down a little to find the D/L.
Just another crazy idea. The game systems use power, but I am wondering if
you couldn't hook up some kind of system such that the kids could pedal a stationary bike
that ran a small generator just enough to power the game station.
I have no idea if this will work.
Bruce
Quote from: firefox on April 19, 2012, 12:23:40 AM
Just another crazy idea. The game systems use power, but I am wondering if
you couldn't hook up some kind of system such that the kids could pedal a stationary bike
that ran a small generator just enough to power the game station.
I have no idea if this will work.
Bruce
;D Let me know how that idea goes over with the kids.
"Sure, you can play for an hour, Tommy. But first you must do 2 hours on this stationary bike."
rofl
You're mean. I like it. [rofl2]
Quote from: firefox on April 19, 2012, 12:23:40 AM
Just another crazy idea. The game systems use power, but I am wondering if
you couldn't hook up some kind of system such that the kids could pedal a stationary bike
that ran a small generator just enough to power the game station.
I have no idea if this will work.
Bruce
I actually like this idea! I bet it would not take long for them to lose interest in gaming! Either way it would be win/win!
Have you considered wind?
Even the limited number of sun hours in MN, it would probably be a lower cost per watt than a generator. I am building a fully off grid house in central NY, which has less sun hours than MN and it makes financial sense. The cost of panels has dropped so much that all you need is a decent charge controller to match the voltage. Factor in the high price of gas and it is easy.
For arguments sake, let me run through a few numbers. I got a shipment of panels for $.90 a watt with shipping added in. Say even if you bought 1 KW of panels at $1.00 that would be $1,000. I will add in $500 for a simple MPPT charge controller. MN averages about 3.5 hours on a yearly basis. So you could reasonably expect about 3.5 KWH a day. I will use just a one year time line, even though the average system will last 20 years. Even with an extra few hundred dollars for setup, on a one year time line that would be $1.14 per kwh. If you spread that out over the 20 years it will produce, it drops to pennies per KWH. Now that 2kw generator, through many battery chargers, you will likely get 1kwh charging out of it. Under a load for an hour, my generator uses around a gallon of gas. At $4.00 a gallon that is $4.00 per KWH! Even if you got maximum electrical efficiency out of you generator (which is impossible) or your generator is more efficient on gas than mine and only runs on half a gallon per hour it would still cost you $2.00 per KWH. The panels would pay for themselves in the first year and you would have another 20-30 of free power out of them.
Because the whole rest of the system is the same (batteries, inverter, charger, generator) between the two setups, I didn't factor them into the cost.
Also the panels are tax deductable, the gas is not.
A good way to check is to take your current electric bill. The KW hours for a month should be printed right on that. Divide by 30 and you should get a good idea of your current daily usage. If you plan on cutting a large amount from that your family will have some large adjustments to make. Modern electronic appliances have large phantom loads. Power strips and the habit of shutting that off when not in use can cut down on power usage a lot. If planning on homeschooling four children, or either spouse working from home, it is even harder because when of power draw during the daytime.
What voltage are you going with? If you plan on this as a full time residence, you can do 12, but 24 or 48 is usually more conducive. Do you have the components picked out? On your setup plan, for a full time residence, many of the inverters will have the battery charger built in and may be easier for your setup.
I saw you listed a charge controller. I may be mistaken but this is usually for wind or solar charging, and not the generator. Normally the generator charging a battery bank is through what are usually called battery chargers, regulated chargers, converters, or just chargers. I may be nitpicking over similar terms, but I just don't want you to buy the wrong thing.
QuoteAlso the panels are tax deductible,
... PV and wind systems/components until 12/31/2016 on both primary and secondary residence as long as they are in the USA
I read through your posts a second time and a few more thoughts.
Once you install the solar panels, I believe you can count the whole setup of the batteries, inverter/charger, and generator as part of the complete solar system and may be able to deduct all the components. Check with you local tax professional. This alone may be worth the cost of the panels.
The fridge is probably rated for the average house it is to be used in. Probably not a family of 6 with four children going in and out. I would factor in more power usage for that.
The inverter/generators usually gain fuel efficiency by controlling consumption based on electric power draw. Many times devices don't use a large draw of power the whole time the generator is running. When charging batteries in the bulk stage it will draw a large amount of power on a constant basis, this will probably drop your fuel efficiency when charging batteries for a few hours at a time.
Wow, good food for thought, and GREAT info on the tax benefits. I would love to use wind and solar combination, but I am in the middle of 100 foot tall Norway pines, so I am afraid I wont get enough of either.
My wife is a teacher and the kids will be at school with her during the day, so our power needs during the day will be nonexistent. During the summer the long days we have in the north mean very little lighting is required, and we will not have AC. The problem is winter, with very short days and no solar, wind however is abundant! But again, we have 100 ft trees all around.
This past weekend we used about 1.5 gallons for about about 20 hours. This weekend I am going to test it in both econo mode and full power.
I listed the charge controller, thank you for catching that. But if using the generator I do not need a separate battery charger for each battery, or do I?
Not sure about the voltage. I was thinking 12, but am open to any suggestions at this point. what would be the benefit of 24 volts?
I will have to do some testing this summer, but you are 100% correct, I do not want to buy the wrong equipment.
Also, I have no aversion to using a propane fridge. Although if I can use solar I would rather use the free solar to power it rather than the propane.
24 and 48 you can use much smaller wires and smaller amperage fuses/breakers. Very high amperage breakers or fuses are pretty pricey. (3000 watts/ 12 volts = 250 amps without safety margins)
Also most books recommend not more than a string of three batteries in parallel. It gets harder for the chargers to evenly charge the batteries, which can shorten the life of the whole bank. So the amount of same amount of wattage for four strings of 12v batteries, would require 2 strings at 24v or only one at 48v.
If trying to get 1kw of charging out of a charger it would need to charge at 83 amps for a 12v system. While a 24v system would only require 41 amps for the same wattage. Generally the higher the amperage you go the higher the cost of the charger.
One thing that may help you calculate your energy usuage is a Kill-A-Watt (http://www.amazon.com/P3-International-P4460-Electricity-Monitor/dp/B000RGF29Q). Plug this into the wall and then plug your appliance into it. It will track how many watts you use over a period of time. I would recommend having a power strip with the TV and game system plugged into the KillAWatt and track how much is used. You really need to nail down your usage before you start trying to size your battery bank. If you drain the batteries down too far too often, you will severly shorten the life span of the batteries.
24v and 48v have the advantages of letting you run smaller(cheaper) cables from the battery bank to the components. You just need to make sure that when you start purchasing parts that you match the component to the battery bank. A 12v inverter usually doesn't like to be hooked up to a 48v battery bank.
On the tax credits... Everything from the service panel into the home would be there whether it is grid tied or not, therefore none of that equipment can be counted towards the energy credits. However, everything that is used to generate the power, from sun or wind, and to store or transmit that power to the service panel is eligible for the tax credits. At least that was how my tax consultant put it to me and that does seem to make sense to me.
So we counted everything including all the wiring, connectors, batteries, the inverter/charger, the PV modules, pole, hardware... everything from the PV modules up to the service panel. Not the generator though.
Also in NM we get a state sales tax exemption on all components used in the PV/wind section of the system. Check your state, some others also offer that.
Also plan the entire system before buying a single item of hardware. And don't get "stuck" on using any one part just because you already have it. {If there are some 12 VDC components you want to use (like an RV water pump) there are good methods/parts that can supply 12 VDC in a 24 VDC or higher system.}
Don's the man here as well as others but I wanted to share this with you in case it might help:
Don't give up on solar entirely, even one 270 watt panel and a Xantrex C40 charge controller (about $400 for the two these days) would make a difference when the sun is up.
Anyway, here's my little bit of experience: when using a solar calculator (that Don has in a forum dedicated to it) use the least common denominator method -- what I mean is, set the average sun hours to what you'd expect in the winter (so if 3 hours is max in the middle of winter then use that!) and temperatures also (so if it's going to be -30 and the batteries won't be inside where it's warm then use -30)....what this will do is ensure you know exactly what you need at the worst time of year for solar power and will ensure max power availability in the summer when you've got 6+ hours of sunlight to charge with!
For my system I used an average and that was a mistake for the most part. Sure I can run the generator and charge the batteries with my 55amp Iota charger but that only works when I'm there and I'd prefer to have enough power to at least run a heat trace/tape on my pipes when I'm not.....and I can't without risking over discharging the batteries.
So, plan for the worst conditions you'd expect to need power in and consider solar as at least a secondary charging method (after all, if you work then it will be charging your bank when you are at work and thus will cost less when you run the genny -- and don't forget that if gas goes to $5 or $6 per gallon, as some predict it will, then running the genny daily might become more expensive then spending $1k on solar power in the long run.
Here is an article from Backwoods Home on a generator-based system. http://www.backwoodshome.com/articles/thomsen28.html Perhaps it will help.
Now, I know to use the calculator to figure out usage and needs. But, what I need to do is change our lifestyle to fit our system rather than size our system to fit our lifestyle. We plan on using things like LED lightbulbs, charging laptops and cell phones at work/school. One, MAYBE two TV's, new super efficient fridge, gas stove, wood heat, laundry at laundromat.
You've progressed well into the subject since this initial post but I thought it might be useful to got back to where you started. A lot has been said about the generating end...all the techie stuff...but that is not where you start if you live off grid and want to have a reasonable system.
From what you wrote you need about 40 AH a day..and that is not skimping on power. OK, if you think one TV is hardship, add another 5 AH. Let's just say 60 AH to avoid the how much can you skimp argument.
With your battery plan which is 675 AH total and 50% of that (330 AH) for decent drawdown that means you need to charge every 5 days. Have to run the genset with a 90 amp charger for 4 hours once a week. With my generator that is one gallon of gas....if you are burning 3 or 4 something is wrong.
The bonus is that when you run the genset to charge you can do the laundry as you are running the generator anyway. Also, can draw temps in the reefer/freezer down to freeze some blocks of ice that make the rest of the week easier on your batteries.
I think solar is great, but it is not the only solution and not the place to start to see about what is right.
Quote from: alextrent on April 22, 2012, 12:57:28 PM
Now, I know to use the calculator to figure out usage and needs. But, what I need to do is change our lifestyle to fit our system rather than size our system to fit our lifestyle. We plan on using things like LED lightbulbs, charging laptops and cell phones at work/school. One, MAYBE two TV's, new super efficient fridge, gas stove, wood heat, laundry at laundromat.
You've progressed well into the subject since this initial post but I thought it might be useful to got back to where you started. A lot has been said about the generating end...all the techie stuff...but that is not where you start if you live off grid and want to have a reasonable system.
From what you wrote you need about 40 AH a day..and that is not skimping on power. OK, if you think one TV is hardship, add another 5 AH. Let's just say 60 AH to avoid the how much can you skimp argument.
With your battery plan which is 675 AH total and 50% of that (330 AH) for decent drawdown that means you need to charge every 5 days. Have to run the genset with a 90 amp charger for 4 hours once a week. With my generator that is one gallon of gas....if you are burning 3 or 4 something is wrong.
The bonus is that when you run the genset to charge you can do the laundry as you are running the generator anyway. Also, can draw temps in the reefer/freezer down to freeze some blocks of ice that make the rest of the week easier on your batteries.
I think solar is great, but it is not the only solution and not the place to start to see about what is right.
alextrent--Thank you,this was exactly what I needed. I think I can definitely live with this setup.
I was up there all weekend building, and my generator at full power can still run about 7 hours on one gallon. My wife and daughter are losing patience with the generator noise so if I can use my batteries for three days and charge them four four hours every few days while they are at school all will be good. I do plan on adding 1KW of solar eventually, but right now my $ has to be allocated toward building materials.
We all hate the generator noise at the building site too. I only have a 10 amp charger so I bring batteries home to charge on the grid. Pain in the neck to carry them in and out. I ma going to States this week and will bring back a real charger so I can run a few hours off the generator and silence it.
You do not even need LED lights...there are some really good low wattage (12 watts is like 60 normal) bulbs. Cost a bit but last forever and light is better than LEDS. HD has them. I have a 65 watt security light that shines like the sun...like a 500 watt lamp.
I don't even think you need to charge computers off site...they take pretty small wattage ...like 200 or so to run off the line. That is less than 2 amps per hour used.
You can manage the reefer to lower wattage use. 1. No auto defrost. 2. Set to run on timer if the on/off mode is not adjustable. Reefers are commonly set to start up to hold a very narrow temp range. So, they run almost half the time. Plus, start up is 1000 watts and running is 200-300 on a good model. Set the timer or temp controller (Johnson makes a good one) so it starts the reefer at 45 degrees...the food will still be at 40, which is safe. Then let it run to pull the temps down to 30, or even 28. Food will not freeze as the lag behind the air temps is pretty long. This can cut power use by 40 %. When running the generator, run the reefer flat out and freeze some water, which will help keep reefer full (helps to keep temps low when you open door) and also provide some cooling power. This way you can have a washing machine and dryer to run then too. All the comforts of home...maybe better.
alextrent--Thanks again, this is exactly what I need. Real world solutions for living off grid. It is hard for me to keep all the stats and facts figures and numbers in my head in order, but knowing real tangible solutions will help me tremendously as I put it together.
I will def look into the timer for the fridge and the light bulbs. The cfl's I am using now are pretty weak, but you get used to the lower light and kind of appreciate the ambience!
So I think I will start with 6 batteries, 3KW Inverter and a 90 amp charger to hook up to the generator.
I will probably add 1KW worth of solar panels eventually.
So, since my last post on this we have officially moved to our cabin in the woods! We will be living in a camper attached to a 16x30 addition until I can build the Big Enchilada or the 20x30 story and a half next year.I will post some pics in another post. Have been working on the current house and an outdoor shower.
However, I have some more power questions.
I made the purchase of 4- 6V Costco/Interstate 220 Ah batteries and a 2,300W inverter. I have a 2,000W Champion Inverter Generator that will be connected to a 25 Amp charger to charge the batteries until I can add solar. Now, I am pretty certain I have sketched my system correctly, I just need some guidance on how to add the charger into the system.
I will add the sketch soon, but for now, do I just connect the leads from the charger to each end of the battery bank at the same terminals where they go out of the bank to the inverter?
Thanks
(https://i1229.photobucket.com/albums/ee471/jonou812/Snapbucket/817A237E-orig.jpg)
I ran my 55amp Iota charger directly to the battery bank (using a copper bus bar where I also connect my charge controller and inverter) so I think what I see here is the same?
The only issue I've ever had is with my Morningstar MPPT controller which didn't seem to like the Iota charger set up that way for some reason but today when I need the charger (very rare) I just kill the breaker on the MPPT controller and leave it off while charging with the Iota charger and Generator. Saves guess work.
4 Costo 220ah batteries? I didn't see you requirement but I run 8 at my cabin and with a Refrigerator running on the system I don't have any issues even in the winter though I think 10-12 batteries would have been better for long stretches without sun.
Course it depends so much on everything you're running and if you don't have the fridge then you probably can drop half the batteries! lol
(https://i998.photobucket.com/albums/af102/emcvay/Cabin/IMG_0048-1.jpg)
You can see the two copper bars in this picture. I got the idea from MountainDon who's done a much prettier job of installing his (some day I'll clean mine up too but it works for now).
http://www.compactappliance.com/WONDERWASH-Laundry-Alternative-Wonderwash-Washing-Machine/WONDERWASH,default,pd.html?mtcpromotion=PLA%3EAppliances%3ELaundry%3EPortable_Washers%3EWONDERWASH&src=SHOPDISCOUNT&gclid=CPOogqbChbICFeY7MgodTQcASA
We had one these. We loved it.
Solar's scarce, how 'bout wind?
On the batteries, as mentioned, the Kirkland brand from Costco are made by the same manufacturer as Interstate, DieHard, AutoZone's Duralast, Wal-Mart's Energizer and there other new brand??? they are all really good batteries made by Johnson Control; I would not use any other kind other than Optima at 4x the cost. Another great source for batteries especially for this application is the used batteries from cell phone towers. Most replace them annually even though they will last 5 years easily if not left dead for long periods of time. There are towers everywhere owned, by local, national and regional companies, just to see if you can get a hold of them. They usually use like the 4D or 8D batteries used in heavy equipment that are about the size of 3 normal batteries.
Speaking of Costco, one location has occasionally carried the 3x5 industrial grade solar panels for only about $500, which I want to say was a 1kw output at a cost presumably way below retail.
Speaking of Costco again, this may only be applicable for states located where Pacificorp is the power company, Utah to Washington for the most part, but CFL's only cost about $.50 each with their instant rebate program through Pacificorp. At work, we use about 100 of the LED's that are 3 watts, multi LED that look good and save us tons of money, but the output is pathetic and the cost is ridiculous at $10 when you buy bulk. At 18 months old, only one has been bad so far.