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Solar and Wind Power with Battery

 
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Ultimately I want to build a cob house with some earthship features (catching & reusing rain water, solar/wind energy, etc...) but I currently live in a single wide. I would like to go ahead and test out solar and wind energy but I don't want my appliances to use that energy directly, I am wanting to route the energy captured from solar panels and wind to a batter and then have my house feeding off of that battery. Can anyone point me in the right direction for this as I know nothing about it? I need recommendations on good but cheap solar panels, vertical wind generators, the correct batter(ies) I'll need, and how to get all this working together. Any suggestions? Thanks.
 
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Hi Garrett,
Thank you for your first post on Permies.  Sounds like you have the idea but want looking for some direction and take some baby steps.
Reading and researching is the key.  With solar, there are four components:
  • Solar panels,
  • Regulator
  • Inverter
  • Batteries


  • Check out this site as a first step, you need to get the basics squared away: https://red-dot-geek.com/solar-power-basics/  In particularly you need to understand the basic formulae and how to do the calculations.
    You will need to consider a number of things the first of which is what voltage you want going into your house.  My advice would be normal mains power because with LEDs, the power draw is very little.  The down side is that the power is measured by the draw (amps) of the drivers and not the light which is measured in lux or lumens.  The normal globes are measured in watts so the load can be measured simply watts divided by volts gives amps which is the power required over a given time the light will be on = AH. This converts to the size batteries you will need.  You will need this calculation for every electrical appliance you plan to or think you may use.

    With a correctly set up power system, the load will come from the solar/ wind input  and the excess will go to the batteries for storage and then when there is no sun or wind, the power will come from the batteries.  You will need a small generator and charger just in case there are days of no sun and little to no wind.  There are things like how will the panels be mounted, where will they be situated, and the list goes on.

    Look at your endpoint and work backwards to the start.  Have a project book for each component and for your house design, do a course so you can be hands on.  They write books on all this stuff and you will never be able know it all or keep up with the innovations so pick a start date and start point and go for it.  But most importantly, ask questions, and especially of the great folk here.  Each one can help in some way.

    Everything on your list is doable.  Best wished for our journey.

    As for getting around this site for more information, I recommend that you go into your profile by clicking the circle next to your name and start on the scavenger hunt.
     
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    Hello Garrett

    The first step you should take is to make an itemized list of what you want to power, and the expected amounts of power you expect to need on a daily basis.  That is, lights, so many watts for so many hours, TV, how many watts, how many hours, computer, power tools, refrigerator, ect, ect.  The amount of power you'll need will help decide on the system voltage you'll want.  I can give you some general guidelines.

    Small system: 12V; lights, TV:  made with 500-1000W of panels
    Medium system: 24V; lights, TV, computer, refrigerator: made with 1000-2000W of panels
    Large system: 48V; lights, TV, computer, refrigerator, power tools, well pump, air conditioner: made with 3000-5000W of panels

    At my own homestead, on days when nothing special is happening, I consume about 3000Wh of power (3 kWh).  That's just routine day to day living.  On days when there's construction, or irrigation days when I'm pumping water out of the well, I consume 20+ kWh of power.  I built a 48V system that can sustain that power level.

    You will want to buy your electronics via the internet, but it's best to buy both your batteries and your solar panels locally.  Trojan and Rolls-Surrette are good battery brands.  Stay away from automotive starting batteries, or batteries marketed as marine hybrid batteries.  Those don't have the thick lead plates that long-lasting off-grid batteries have.

    Shop for your solar panels on Craigslist, or Ebay, but with local pickup only.  If you buy panels off the internet and have them shipped to you, you pay much, much more.  Expect to get good panels with local pickup for about 3-4W/$.

    These days, both batteries and solar panels are wired in series to provide greater capacity.  Today's electronics handle that seamlessly.

    If you plan on running anything powered with a motor, such as power tools, refrigerators, freezers, or air-conditioners, stick with sine-wave inverters only.  Avoid square wave or modified sine wave inverters, even though they are cheaper.  Your motors will overheat and live shorter lives.

    The best inverters are designed to be hard-wired directly into your house's main electrical panel.  I would avoid cheaper inverters that provide the power through NEMA sockets.  The best inverters will provide split-phase AC, so you can run both 120V and 240V equipment.

    More likely than not, you will find that most of your power is actually produced by your solar panels.  Wind is far more likely to disappoint you than solar will.  Keep asking questions, and we'll be happy to answer them.
     
    pollinator
    Posts: 3415
    Location: Massachusetts, Zone:6/7 AHS:4 GDD:3000 Rainfall:48in even Soil:SandyLoam pH6 Flat
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    I am not too sure if septic tanks, solar panels and rain water catchment are considered earthship features. But I understand what you mean.
    I would 1st figure out how much, water/electric/heat/etc you will need per day/month/quarter/year.
    Next I would figure out how much you can produce on-site given your constraints.
    I would then setup some backup systems in place.


    SOLAR PANEL
    Electricity, lets assume you follow the average and use about 1,000KWH per month or about 33KWH per day.
    Daily Production = Daily Usage = 33KWH
    Daily Production = Array Size x Solar Hours
    33KWH = 10KW x 3.3Hours (4hrs probably turns into 3.3hrs after system losses)

    10KW solar array is about 500sqft, so your roof is probably big enough.
    Solar panels have heavy metals in them so I don't recommend drinking water from solar panels.

    $5,000 Solar Panel 10KW
    $2,500 Solar Panel Support/Misc 30panels
    $10,000 Inverter/Charge Controller 10KW
    $10,000 Battery Pack 33KWH
    $5,000 Back-up Generator 10KW
    $2,500 Fuel Tank


    WIND TURBINE
    A 1,500W wind turbine actually requires 27mph winds, and that is the wind that they assume that the site will have.
    That same wind turbine in 10mph winds will only produce 150W per hour or 3.6KWH per day, and very few site actually posses the pitiful avg wind speed of 10mph.
    So I normally don't recommend wind turbine. But lets say you threw caution to the wind and got 15,000W of wind turbine to compensate for the 10mph winds (aka you got ten 1,500W wind turbine)

    $10,000 Generator 1500W @ 10mph (but 15,000W at its rated 27mph)
    $6,000 Controller + Dump Load 2KW
    $10,000 Battery Bank 33KW
    $9,000 Inverter 10KW


    HYDRO
    Daily Usage = Hydro Production = Generator x Hours/Day = 36KWH = 1.5KW (generator) x 24Hours
    Stream-Generator Net Production = Flow X Height X 1/10
    1500W = 100gpm x 150ft x 1/10
    1500W = 100 x 15
    1500W = 1500W

    $5,300 PVC Pipe+Weir/Dam+Misc
    $2,200 Generator 1500W
    $1,000 Controller + Dump Load 2KW
    $10,000 Battery Bank 33KW
    $9,000 Inverter 10KW


    WATER SYSTEM
    The average person uses 70gallons per day or 2,100gallons per month.
    Water Production = Water Usage = 2,100gal/month
    Water Production = Roof Size x Rainfall Amount x 1/2
    2100gallons = 1000sqft x 4.2inch of rain per month x 1/2
    2100gallons = 4200 x 1/2
    (Maybe you will have a roommate or a partner or visits from family, so I would plan for a 2person household vs just one aka 4200gal/month vs just 2,100gal/month. If so you are going to need a much bigger roof.)

    Water Usage
    Toilets 18.5gal
    Clothes Washers 15gal
    Showers/Bath 12.5gal
    Faucets 11gal
    Dishwashers/Misc/Leaks 13gal
    Total=70gal/day/person
     
    Paul Fookes
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    S. Bengi has some good figures that are a really good starting point and well considered

    Our house has never been on the grid, we collect our own water, have solar hot water with a wood fire backup water jacket in the chimney
    For our power we have two dual axis trackers with 2 Kw on each, each set of 5 panels has its own regulator (1 Kw) and 2,000 AH battery storage
    the 2KW inverter powers 1 X fridge, 1X fridge freezer, 1 X tucker box freezer, front loader washing machine, electric kettle, lights computer and electronics, workshop and the normal range of lights and fans, TV and video.
    The only time we get an issue is if the washing machine and kettle are on at the same time as the kettle is 1800 W.
    Our batteries last over 7 days in overcast and very cold winter days.  Our back up generator is 800 X and the battery charger is 40 A.
    Our total system rebuild cost A$20,000 which is about USD 15,000
    You will need to do your own figures but it is better to have a bit spare because it is likely you will get more toys as the build progresses.  We only use battery powered tools, including our mower and brush cutter. which are charged during the day.

    When you calculate your water, multiply the annual figure by the number of years of the longest drought and add 10% for losses.
     
    Garrett Gaston
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    Thanks everyone. As far as powering appliances goes I'm just trying to learn and don't want to sink too much money into it, nor do I have a lot to sink. I think right now I want to see what I can do with a few panels getting the most important things off of grid dependence, namely the fridge/freezer, and then slowly grow from there. One question, I noticed several of you mentioned a generator, I'm not planning on going off grid right now, maybe after I build a cob or earthship house but not just yet so would I really need a generator?

    I mentioned that I was wanting to have the solar/wind power feed energy into a battery and then have the house, or at least a few appliances from the house then feed from that batter. You said that the conventional setup is to have the energy from the solar/wind go directly to the house with only the excess going to the battery. Since I'm not getting of the grid just yet, would that setup cause power from my power company to keep feeding the battery that is really only there for the solar/wind? Thanks all.
     
    Rocket Scientist
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    Ha Garrett;
    Everyone is already building your earthship...
    They have skipped over the fact that your currently in a mobile home hooked to power.

    The parts and supplies for a tiny starter system are much less $.
    Some of the supplies may not be suitable when you upgrade to completely off grid.

    Meanwhile  Your idea to learn now is a good one.
    However your goal of running your Fridge/freezer is a huge mountain to climb !
    They use way more power than the manufacturer would like you to think.
    A  stand alone solar/ battery  system would need to be very large to attempt that.
    They do make DC 12 vt  fridge / freezers.
    I have been 100% off grid since 1983.   I owned a conventional chest deep freeze .
    I paid my neighbor $100 a year to keep it at their house...
    I now own a Sundanzer 12 vt chest freezer and love it so much that I have an order in for a second one.
     
    pollinator
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    Haha, I will also second the idea of building a small system at first to get your feet wet. Putting together a system that is capable of producing 30kwh each day as your first project would be quite an undertaking.

    Doing lots of research at this phase is going to be critical to success. One suggestion I have is to get a plug-in watt meter that will let you start getting an idea of how much power your current appliances actually use. Everything with a cord will have a stamped nameplate that shows the max power consumption - which is great for working out loads on things like a radio; if you know how much it draws, and how long it will run, it is easy to come up with an energy budget. A fridge is trickier, because the compressor runs intermittently; and the usage will change depending on how much you open it and ambient temps.

    As a general rule, an upright fridge might draw as much as 1000Wh per day. A better option for off-grid is to convert a chest freezer. I have a 5cu ft model that runs on an external thermostat, and it draws 100 to 200 Wh, depending on ambient temperature. Freezers need more power, so that might be something to work up to. I want to say I looked up that a small chest freezer should draw something like 750Wh per day, but I have not tested it recently.

    How big a system you are going to need will depend a lot on your location. I need 3 or 4 times more solar panels here in Oregon than if I lived in the Arizona desert, for example. And unless you have gnarled wind-swept trees, you probably dont have enough wind to justify a turbine. At least not yet. When you get a better grasp of how much power you really need, you might revisit that idea. Even a tiny turbine can add up to a lot, if you pare your system down to a reasonable size.

    Anyway, good luck, and fire away with questions
     
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