another off grid Q:

Discussion in 'Homesteading Questions' started by okiemom, Jul 21, 2004.

  1. okiemom

    okiemom Well-Known Member

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    Hi all,

    I am still wondering if I can run small A/C units off solar. I am asking because i think I would be OK w/o A/C if ther was a cool room in the house. I know some are in favor of ground homes but I just can't do it. I am a sun/ light person. In winter I can feel the lack of sunlight. I am willing to go w/ super insulated, High ceilings, light roof and wall color, and lots of windows and doors for cross ventalition.

    Is there a way to have a generater hooked up to the batteries and if the batteries go low the gen. will automatically kick on? Do you have to manually start the generator? I can't imagine how it would start on its own but I'll ask a stupid question anyway :D . We can put a man on Mars but we can't get a small engine to start on the first pull of the cord!!!???!?

    I am wanting a hybrid System: Solar panels, generator and very possibly a wind terbine. If the solar and wind are working together ( sunny and windy) why can't I run a small A/C unit or whole house fan during the hottest parts of the day. Can you tell I am not an electrician :D ;) ?What am I missing?
     
  2. Oregonsparkie

    Oregonsparkie Well-Known Member

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    Yes you can run a small A/c from batteries and an inverter. Unless you get alot of consistant wind about 5 - 7 mph then I wouldnt mess with the wind part.

    Yes the generator can be hooked up to sense the drain on the dc system and automatically come on.

    Solar can be very expensive. If you get several deep cycle batties hookup together then it will help balance the drain. Eventually you may have to recharge the battery bank.

    Is your house off grid right now??
     

  3. big rockpile

    big rockpile If I need a Shelter

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    Why don't you find an old Refer and really cool down,run it off Diesel?You can just use a Compressor,use air to run Fans.

    big rockpile
     
  4. fordy

    fordy Well-Known Member

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    ......................After looking into most facets and combinations of "off grid" power....here is my basic assessment....(1) Solar is TOO expensive to power high Amperage appliances such as Window units, Microwaves , electricial ovens , etc. A Small diesel genset of 6 to 10kv will ALWAYS be the optimal choice to power these types of items. Therefore solar, batt's , and windgin's all interfaced together via a control panel should be relied upon for LOW Wattage needs like lights, ceiling fans , computers, etc. The ONE exception to this would be to have a battery\solar system and converter that would power a Water well so that it could Cycle thru and replenish your pressure tank as needs dictate on a 24 hour basis. Solar panels become prohibitive in cost because as you increase the number of panels you also have to Ramp UP the size of your Inverter or the maximum capacity of the panels will be lost.......fordy.... :)
     
  5. texican

    texican Well-Known Member

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    Hi Okiemom
    My home was offgrid for 12 years, so I can speak with some experience.

    Off grid systems ARE expensive. There are two kinds of people who go offgrid...those who want to "help" the environment, and those who can't afford to get wire strung to their house.

    I fall mostly in the second camp. Our local co op quoted me 80+K to run wires to my home, plus I had to clear and negotiate r.o.w.'s over 2 miles of timberland...the money was too much and the timber co's wouldn't dream about letting some of their acreage go.....

    You CAN run anything off of solar/wind/hydro aka off grid.....if you are willing to spend enough money. The larger the load, the larger the battery bank, number of panels, controllers, and inverters you'll need. Adding a couple hundred watts to my system was going to cost several thousand extra bucks...I was looking at a larger inverter, better/larger batteries, another expensive controller, and several thousands in panels...all for a couple """hundred""" watts. I still wouldn't have been able to use any kitchen appliances, ac units, or any resistive load. At a certain point, if you can't live without some modern luxuries, it becomes just as cheap to bite the bullet, and string the wires to the electric company. I was shopping for upgrade parts when my neighbor strung wire on his property, half a mile away. I was able to hook up to the grid for ~2K. My bills are in the 30-40 dollar range each month. When I went on grid, I got most of the modern conveniences that most folks take for granted...microwaves, toasters, monster ice box, freezers, etc.

    I used my solar for tv, stereo, lights, and a couple of small fans to move the hot air around. My system produces about 350watts/hour....to run a super efficient dc icebox, I'd have to triple or quadruple my setup. To add a small ac unit would've killed my system....it would have needed to be ten times as large. Just not financially possible.

    Yes, you can add a generator to a system. Some of the TRACE inverters'll start your genny up remotely, charge your batteries while powering up your heavy loads. A reliable genny that'll last more than a couple months (most genny's are for intermittent use...running them all the time will wear them out in a hurry) will run you about 2k, one of the good TRACE's'll run you at least a grand. Look for a natural gas/propane genny, you can use the same gas for your gas fridge and cooking...besides the propane genny'll last a lot longer.

    If your building a house, build it under trees, especially blocking the south and west corners, and all of the roof if at all possible. My home is under huge oaks...my interior temp is around 74 to 78 when it's a 100+ day outside. A ceiling fan to promote a breeze is sufficient 99% of the time. I've turned on my ac wall unit twice, to cool off in a hurry, and remove gallons of moisture generated by an all day canning session.
     
  6. rambler

    rambler Well-Known Member Supporter

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    A person _can_ do all the things you ask about.

    The problem is $$$$$.

    A simple low-wattage solar electric battery system to run a couple 100 watts of draw costs several thousand dollars.

    A system to run a high-amp on-demand draw like central air conditioning would cost maybe more than $20,000 plus fuel & maintenence.

    Everything you add will cost money, and possibly reduce efficiency. You can have a self-starting generator that watches your system & uses the battery bank to start itself & charge the batteries. But notice, it actually uses electricity to monitor the system. The solar pannel system needs some monitoring equipment. If you add a wind charger, that will need it's own set of monitoring equipment, and over-charging controls, and so on.

    A big, huge, high-amp inverter will draw a lot of amps while not even being used - just sitting there waiting for your air conditioner to start. While a low-cost few 100 watt inverter will hardly use any power at all while in standby mode.

    Say you are running a couple of lights - with the little inverter, it will only draw 100 watts to run 2 25 watt lights. But if you have an inverter to run a 10,000btu window unit, then even if you are running nothing but those 2 25 watt light bulbs, that big inverter will probably be drawing 5-600 watts just to run the bulbs. Bigger is less efficient.....

    Now, you can maybe find a 12v air conditioner, & bypass the inverter issue. Won't be whole-house, but like from an RV. You still need a huge battery bank to power this, and many many solar pannels.

    By the time you get everything hooked up, you might as well throw the solar pannels away - their production will all be used up by just the monitoring, interconnection, & standby equipment - you won't get to use any of their power. The only thing you can afford to power the air conditioner will be the diesel or LP generator.

    So, unless you won the lottery, you will have to decide how much money you have for the total electrical system, and how those dollars can best be spent. If you go solar, you get 'free' electricity, but there are extreme limits on the number of watts you have available at any one time. Wind generators can produce much more amps for the dollar, but _only_ now and then, not when you actually demand the power, and it is very expensive to store electricity until you need it. Engine generators produce power when & as much as you need, but require a lot of fuel & maitenence along the way, and have noise & fumes.

    Tying all three together looks good on paper, but you are spending money on three seperate systems, plus you need to tie them all together which costs more money, more complexity, and uses power just to run itself - perhaps more than one of the 3 systems actually produces....

    If this were easy or cheap, everyone would be going off grid. :) You need to make hard choices if you do go off grid. Or, have very, very deep pockets.

    --->Paul
     
  7. Thumper/inOkla.

    Thumper/inOkla. Well-Known Member

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    All of the wind generators I have read about have all the needed controls built in and are hooked strait up to the batteries.

    Our 2 -100 watt panels cost $500 each, the charge controller was about $150, wire maybe $100, our sealed deep cycle batteries where used and we have 8 for $15 each, (major savings on them!) our inverter $400, designed for a big truck and it has low voltage shut off to protect batteries, we have radio/cassett player with speakers up stairs and down as wells as 12 volt lighting run strait off the batteries, the computer/printers/scanners color tv/vcr, and dvd player all run through the inverter.

    On sunnny days we have more power than we can use up, our generator is a manual start but it is all hooked up to a good quailty battery charger, which is in turn hooked up to the batteries, so it charges every time it is started up.

    and by learning how it all works we can add to it or up grade anytime we want.
     
  8. Dreams30

    Dreams30 Lady Rider

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    Thumper,

    Do you have any kind of refrigeration in all that?
     
  9. Thumper/inOkla.

    Thumper/inOkla. Well-Known Member

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    The closest we have to cold, is buying ice every few days,we have good enough credit to get a loan for a fridge, but I really want out of debt. Even if we bought ice every day of the summer it is still cheaper than a set up for a fridge, so we wait, we chose to get horses, so our extra money is going to them for now.

    I am happy with our goat milk unchilled and it keeps just fine for 24 hours, if I don't use it by then I have already milked again or I am about to, fertile eggs are ok unchilled as well, it takes 4 days of nearly 100º to show a germination spot, that is big enought to look gross, and the eggs is still NOT spoiled, it is useable [if I had to use it], try that with a store bought, unfertile egg {yuck, I think not} hamberger will not keep, but steaks/roast can last 36 hours or more, with proper handling without a fridge.

    We have been here 2 years now, and we are doing better and better as we go along.