We are building a cob home in northern AL and have begun exploring our off-grid options. I don't know much about solar or wind except for what I have researched. In doing so, I'm left with more questions than answers. We could have on-grid power run to us for free if we wanted to allow the power company to mow a 40 ft by 400 ft strip of our land down and maintain that strip however they saw fit (which includes a healthy dose of "weed spraying" twice a year--YUCK!) We also have the option of running a sub panel off my mothers' home, but that would cost us around $3-$4K. I figure if we're going to spend that kind of money anyway, we should explore our possibilities of off-grid power(which is what we wanted in the first place). I'd like to be able to have about 100 amps of power available. From what I've read, this may be asking a lot considering we are on a tight budget. I should note that my wife is an electrician and both of us are very capable of DIY set-ups. Any help in any direction would be greatly appreciated!
Is this your peak power usage or your regular power usage. How long is this duration 1hours or 12 hows.
How much do you need per day total and also per month.
I use about 100KW per month or 3.3KW per day. So with a 1KW solar panel with 4 hours of winter sun I would be ok.
Battery (should never be more than 1/2 discharge and should last a full day without sun, 4kw) 3k
If you have a good amount of night breeze you could also get a 700W windmill (less than $1,000).
And then you would spend less on battery storage because you would be making electricity in the night too.
Reducing your electric demand would be a first step. Those big screen TVs, heated dryers, and self cleaning ovens are convenient, but not practical. Do you really need the fingernail polish dryer?
Moving systems away from electric is also a safe bet. electric heat is so convenient that I would hate to give it up, but it eats something like 10000 watts of power.
Utilizing an array of energy technology seems to make a great deal of sense to people far and wide. Solar space heating, solar hot water, and even solar cooking can offer energy without buying or gathering a fuel. In our deep south location, solar thermal systems are competitive in price, and a bargain if you construct the systems with off the shelf parts. The use of scrap, recycled, and repurposed material can give you a useful energy source for the investment of time.
Wood and biomass also makes a fine energy source or backup for those rainy days. A woodstove can heat a space, heat water, and do your cooking. These forums have copious amounts of information of rocket stoves and rocket mass heaters, and people with experience in construction and use. They won't steer you wrong.
Gas is a possibility. A 20 pound tank of propane can give you convenient cooking for several weeks, and be refilled for around $20. That one is hard to beat. Just the wire from a breaker panel tp an electric stove is going to run you several times that. Sure is handy to have independent redundant system. Larger gas tanks can be set up to operate water heaters, space heaters, refrigeration, even clothes dryers.
If this is all you put together, a photovoltaic system would be much smaller and less expensive. That $3-4k would go a long way in meeting the needs that remain: well pump, lighting, refrigeration, alarm clock and home electronics.
One particular advantage to solar electric is that you can add on later. Get a couple more panels, a couple more batteries, upgrade the charge controller or inverter when the time comes, maybe sell your old one on this forum. Its possible to add a wind turbine to the electric system if you have dependable wind in your area. As far as your best options, that decision is up to you and your situation.
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Location: Hamilton, AL
posted 5 years ago
Thanks for your replies folks. Let me try to answer some questions. For heat, we will utilize rocket mass heat in the house. For cooking, I use wood fire or gas, but I do have an electric induction burner I love for those rainy days. It does suck the power though at peak output (1800W). I don't own a TV (rots your brain and wastes time), DVD player or any of that crap. I wish to run a refrigerator (for the time being), a medium size chest freezer, a few lights, my MAC, and a guitar amp (when my brother plays electric), and a few power tools (when required).
I suppose I should back up and present the whole picture. We're situated on 80 acres of land, 40 of which is ours (my mother, brother, and me), 40 of which is my Great Uncles. While we build, we are based out of a (self) converted tour bus, and my brother is based out of a converted school bus. Our bus is not the model of efficiency for heating/cooling. It's hot in the summer, and cold in the winter. For the time being we're hooked up to the electric and water at my Uncle's cabin, but our permanent parking space is ready (minus the power) for us to move to. We use 2 small window units for cooling in the summer and electric heat currently. My brother has a wood stove for heat and a small window unit for cooling. I am looking at changing the heat to gas as the electric draws too much and produces too little for the price. A small wood stove is out of the question in the bus, as all available space has been utilized (we have 2 young children..nuff said). We are figuring to have to spend at least another complete season on the bus, but maybe longer, lots of variables. Our current set-up demands no more than 40 or so Amps at the most (forgot to mention the electric instant hot water heater), but even that is a stretch if we ran everything at once.
My wife originally wanted to install a 200 amp service because 1-she's an electrician, and thinks one always should have the power available if you're going to do it and 2-we're thinking long term for things like having power available to a barn, chicken house, and possible well pump, but that's all hypothetical at his point. I suggested down sizing to 100 amps for the long term, but the overall price doesn't change much. All of the work we've done thus far was done utilizing re-purposed material. I don't buy anything new if I don't have to, there's too much great "junk" available to not use it. If we can make our own solar panels, or find someone else who can (time is always an issue) build the for reasonable, I'm all for it. I refuse to buy any of the manufactured systems that make exagerated output claims and cost waaay to much. I'm looking for the most "bang for the buck" and am totally willing to (continue) simplifying our power usage to make it all work. Perhaps this will add clarity to our situation.
What is your one biggest thing you want to run? Central AC, welder, table saw, deep well water pump, etc... How much will it cost to build and maintain solar/battery system to run it? How about a generator? For me it was obvious it was the low cost (and actually smallest carbon footprint) answer. I don't use the power tools enough to justify anything else.
The "regular" loads for a house can be made VERY small. The new led lights take no power (not enough to even turn on some inverters) and you can light a big house on 25-50 watts. Choosing the right fans and appliances can make similar impacts. You can build a simple solar system to cover those loads.
My system is evolving based on the info found here: www.battery1234.com
I am a convert to the little inverter generators like the Honda EU2000 and the little window air conditioners that they can run--look it the best current models on the RV forums. They will make the worst summer days/nights tolerable in the deep south for a few cups of fuel. And they can run on ethanol if you can make it.
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100 amp or 200 amp on solar or wind is too much to expect unless you spend a LOT of cash AND have optimum conditions.
If you get propane/gas or super-efficient appliances including water heater, dryer, cooking range, fridge and freezer, there is no way you will need 100A service unless you are running some huge power tools or a welder. (My arc welder is on a 50A breaker). Also get low voltage DC led lighting, etc.
One thing that won't work very well off grid (because it uses so much power) is those heating elements you use to keep livestock water from freezing. But you're in AL so you might be okay. Anything with a heating element (hair dryer, toaster, oven, water heater) uses a lot of watts.
But be realistic, cooking with wood is fine in the winter, but are you really wanting to do that in the summer in Alabama? I would get a propane/gas cooking range, but be careful because most of them won't run the oven without 120V connected! (there is a solenoid that shuts off the gas when power is disconnected, meaning it is using 120v power 24/7). Unfortunately, if you look on craigslist or something for a gas range, the seller won't know anything about that so he won't know if it needs power or not. (We off-gridders are a select few.)
I recommend get one of those Kil-A-Watt meters (they're like $20), measure power from all the devices you want to use (don't forget your well pump, you might have to estimate), then go to one of those solar websites with solar panel array calculators, put in your numbers and see how many KWH you need. If you don't want to get the meter, there are websites that can give you estimates but IMO its better to know the real thing.
When the wife does the wiring, she can put light switches on all the receptacles so they can be completely shut off when not in use. Basically every room will have two light switches, one for the lights, and one for receptacles. She can also run DC-only circuits: common accepted practice (don't know if its in the NEC) is to use regular 240vac receptacles for 12vdc outlets which you can then plug a phone charger or dc lamps or whatever into.
Then get a big propane generator for those times when you want to run the welder or whatever.
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even distribution
So I would go with solar electric for regular house electric, plus a solar water heater, solar ventilation, plus RMH, RMS.
Then for the tools that you run get a gas generator, run it for the few hours per week that you use tools for.
A gas water heater and cooker for convenience ever now and a again is a nice backup.
There is also a solar oven, its pretty much sunlight heats up chest of salt. salt is encase in R-90 insulation on 5 sides once the sun goes down the collector side is covered with another slab of R-90. It will stay at 450F even 50hrs without any additional sunlight due to insulation. to cook you just stick your pot in the salt. I think I saw this device on builditsolar but you can search around for it
just out of curiosity, what exactly must yu allow the electric company to do and for how long? It could be very nice to have all that electricity during the building process.
I do not know how long you will be staying on that bus but it sounds uncomfortable now, you might want to stick up some insulation (at least under the unit) to keep the temperature better.
That was a good point about a wood burning stove in the summer. Personally, when i am working, i would not like to think my salt is outside and now it is raining. It really is very much possible to have a place you cook inside in the winter and a second cooking area outside for summer months, this was often done before everyone had air conditioning. Many people had summer kitchens, actual small buildings where the cooking and canning was done. When thinking of going off grid this is one custom to think of resurrecting. Before getting too complicated with this thought, for now, maybe you can make a cob oven to cook outside in.
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