Calculate energy usage

Discussion in 'Designing, building, making and powering your life' started by Paddy82, Jan 3, 2010.

  1. Paddy82

    Paddy82 Junior Member

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    I'm a real dummy when it comes to electricity, but I feel I need a certain sense of it to go forward with my plans on permaculture grounds.
    I was planning to get a WindTamer turbine(Seems to be the best atm, unless you have better suggestions?) for my future eco-home, but I really have no idea on what size it should be. The information on calculating it is there, I just can't wrap my head around it. Are there charts for 'normal consumption' on a building of a certain size? That would be really great.

    Of course my plans include using only LED- lights in an otherwise super-insulated home, and the energy would not be required for heating (Will use other sources for heat).
    At the moment we pay around the equivalent of 78 AUD per month on 84m2 living space. However it's the middle of winter here (skyrocketing prices), and I have an expensive (energy intensive) hobby, which I will largely do without once we move.

    Any help on clearing this up, and suggestions are most welcome.
     
  2. gardenlen

    gardenlen Group for banned users

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    g'day paddy,

    best suggestion go for a dual system, keep cable runs as near to source as possible, so a simple design home works wonders, you power users won't be lights if you build right, they are fridges and freezers and tv's, computers and washing machines. for w/machines and fridges etc.,. maybe consider changing them to 12 volt so their power does not need to go through an inverter.

    not sure where here is with you but obvioulsy northern hemi'. if youa re in the US there are many into stand alone power using dual systems look on the 'net for those forums.

    for this to work you'll need outside the box and comfort zone latteral thinking, do good driven by indoctrinated values (yuppieism).

    len
     
  3. Paddy82

    Paddy82 Junior Member

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    I'm in southern Sweden.

    Does a "dual system" mean two rotors? One fails, the other one kicks in? Sounds sound, except for the double investment, but on the other hand the second rotor could be a less powerful one, running only the bare essentials... Hmm you gave me food for thought- Thanks!

    So basically I need to calculate all the machines I will have and add up all their power requirements, to get a peak consumption estimate?
    Any thoughts on good batteries to use as a lifeline? Preferably ones without death in them.
     
  4. pebble

    pebble Junior Member

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    Alot depends on what your motivations are in building and living green. If you want to 'powerdown' i.e. use meaningfully less resources in your life (as opposed to just keeping the same lifestyle but trying to green it up) then I'd suggest going completely 12V. It's a more efficient use of electricity, and you can work with it more safely than mains power. It does mean that you can't just turn things on and forget about them - you have to be conscious about what you use and when. But this is what we all need to be doing anyway.

    Not sure you can do that on a grid tied system though. Are you planning to be completely off grid? Or wanting to sell back to the grid? What voltage is mains power in Sweden? It would also help to know how high or low tech you are going. Want to have all the mod cons? Or are you wanting to live a simpler life?

    To do an energy audit, you need to decide if you are working in mains or 12V (or whatever, some people use 24V).

    Then you list all the things you want in your home (inside and out) that need electrical power (take some time to do this, there are always more things than we think).

    Then you need to think about how much you use each item (need to use the washing machine daily or weekly?).

    Then you have to list what each item uses in terms of power. On every electrical item there is a rating. But in order to do this you do need some understanding of how electrical things work. Do you understand what volts, watts and amps are?

    Battery choice comes a bit later, because it depends on how much electricity you need and how much you can generate. You need to match the battery size(s) to the output on the wind generator and any other power sources you are using.
     
  5. springtide

    springtide Junior Member

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    If you just want to live greener then go the grid feed system, if money is a bit of an issue then get a larger inverter so you can always add more stuff at a later date
    If you want to get off the grid then consider some kind of TAFE or equivalent short course in electronics (Extra Low Voltage, cars, boats and general stuff) it is quite easy but there are a few important basics to do it safely and properly. If your toying with the off the grid idea then you might be looking at a few low voltage appliances just to see whats out there - think 24 Volts!. Unless its a holiday beach shack the highter voltage means thinner (cheaper) cables and less volt drop (voltage slowly decreases with distance likewater pressure in a long garden hose), this will be especially important if you are considering a few wind turbines as they will have to be 20-100+ metres apart therefore you will have to run long cables!
    Off the grid is a hassle and currently only my garage and beer fridge run directly off solar + batteries (grid feed in system on house) but it is so cool to have that tiny bit of independance and when the power goes out i run an extension lead through the house, turn on the kettle and watch some TV.
    Good Luck with it all >)))">
     
  6. Paddy82

    Paddy82 Junior Member

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    It's a little tricky to be very specific because I'm still in the stages of looking for suitable land. If I already knew what I ha d to work with it would be easier, and I realize it's hard to answer abstract questions =)

    The plan is to, as you put it, power down. Other than that I'd like to be properly off grid, but if legislature regarding private production of electricity ever changes here, I may be interested on feeding surplus power back to the grid, but that would be the only reason for plugging in, and I don't expect it to happen anytime soon.

    Mains power is 240V (except for some stoves which are 400V, but most of those are obsolete). Lo-tech is fine as long as it is functional, I don't intend on putting a lot of time and energy on constant repairs in an area I know nothing about.
    Whatever needs to be high-tech though, should be (If we're thinking the same thing it's TV, oven and stove primarily). Although I'm planning to do without a TV (never use it anyway), I will stick with a computer, and an internet-uplink will preferably be the only thing that "connects me". A washing machine is a must though. So basically, it's kitchen machines, computer and washer. And lights.

    Of course the aim is to get whatever appliances that use the least amount of energy at that time as well.


    As for 12/24/240V I am unsure. Seems to me that to convert everything to something other than the normal 240, you'd REALLY need to know what you're doing... I have a friend who's an electrician and I'm sure he'd help me out, but I don't want to over-exploit him doing really substantial and/or complicated work.


    Money is always an issue and of course I don't want to spend more than I absolutely have to. It would be nice to have some space to add the odd bit and bob sometime in the future, should I need it, but I don't understand how the inverter comes into play here.


    Hope I managed to get a few things cleared up...
     
  7. Paddy82

    Paddy82 Junior Member

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    I just saw this and this, which were really inspiring and I'm starting to understand what you mean with running on low voltage DC instead.
     
  8. pebble

    pebble Junior Member

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    Yes and no. I still think you need to make a list of the electrical things you will want in the new house, and how much you will use them, before you can go much further. You've listed a few things, but does this mean you have a non-electric landline phone, no cell phone, you never charge batteries (eg torch)? No stereo, radio, dvd? What's in the kitchen?

    I live in a housetruck on 12V, with a pretty basic system that is enough to power lights, water pump, computer, tv, charge cell phone. I could easily up that system to include more power. Parts of the year I have access to mains power, so if I was to go completely off that I would need to be more organised, it's not that hard. But, I don't expect to live a mains powered life, with lots of mod cons.

    I don't use 12V electric for cooking (gas and wood), or heating (wood, passive solar), and those are pretty big differences than mains powered houses.

    For me the powerdown is about a number of things: living more lightly on the planet for sure, but also I expect that there will be times in my future where there is no guaranteed mains power, and I want a life that is livable in the long term. So you have to think about things like maintenance. I can repair 12V wiring and do maintenance on the system. I can't build a solar panel or battery. The worst case scenario is having no electricity at all, and eventually my system will be set up for that. In the medium term solar works well.

    So I'm still not that clear about what powerdown means for you. There is a huge range of what people mean by that and what they mean by a green house. Some people have a lot of money to spend and design big systems, others (like me) have less money and want to live simply. Something else to consider here too, is what kind of lifestyle you have, and how hands on you are. For powerdown and going green you really need to live in a small house in your climate. People who design big houses with lots of mod cons are not doing the planet any favours even if they go off grid. And things like passive solar are incredibly important if you want to go off grid in a meaningfully green way.


    Here's the list you have so far:

    Cook stove (why not gas or wood?)

    Washing machine - how often will it be used?

    Computer - how much use?

    Router - how much use?

    lights

    other kitchen appliances - what exactly?



    The thing about 12V is that it uses less power. A solar panel outputting to 240V gives you less power than to 12V. I'm not sure about what springtide is saying - I've not used windpower, so you'd need to get advice about the loss of power over distance (this is not an issue with solar).

    You have a couple of options with 12V. Either you run all appliances on 12V (eg my computer uses a 12V to 24V adaptor, not a mains plug), or you run as many as you can and you get an inverter to convert 12V to 240V (but you lose efficiency this way) for the rest eg I'd guess it's hard to buy a 12V router (although the mobile home crowd are getting more and more appliances made for 12V).

    12V isn't any harder to work with than 240V, in fact it's easier because it's much safer. 240V needs a registered electrician, 12V doesn't (not here anyway). Once you understand electrical basics then 12V is pretty straightforward.


    Hard working hippy who posts here sometimes has a blog about their place that is all on 12V (wind and solar). They're in France, so might have some ideas about what's best in Europe.

    https://lafermedesourrou.blogspot.com/search/label/Off-grid living
     
  9. springtide

    springtide Junior Member

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    Out of interest, power equalls volts (V) multiplied by amps (I) and is expressed in watts. So you can have 20 amps at 12 volts or 1 amp at 240 volts - its the same power.
    To give you an idea of cable size...
    10 amps at 12 volts over 50 metres requires 37mm2 cable (35mm2 is a standard size and you can pay up to $15 per metre - but you would need 2, one for active, one for neutral)
    10 amps at 24 volts over 50 metres is half the size - so about 18mm2
    and at 48 volts its 9mm2 - 10mm2 is a standard size and you can pay up to $5 per meter.

    So a theoretical 50 metre run from your house to the top of a hill for a 500 watt (41 amps) wind generator would use 2 lengths of 150mm2 cable (at a guess of $60 per metre)
    or at 24 volts the guess would be half the size and half the cost at guess of $30 per metre.
    Shop around for anything like this but thats what i found online.

    Then there are switches and fuses and stuff, 100 amp switches are easily availible from shops like jaycar or ebay but at 12 volts this is only 1200 watts so your using the washing machine and someone turns on the television and the switch melts - at 24 volts the 100 amp switch is good for up to 2400 watts which will do just about anything.

    The reason i said 12 volts is good for a holiday house is because in a worse case scenario when you arrive and batteries are flat and there is no power then you can hook your house up to your car and charge things up - in a larger permanent residence you might want another contingency plan (small generator, etc).

    To power down with access to loads of fire wood you don't need a lot of stuff - but with kids, job, new house with no established gardens and limited firewood supply i am thinking of something a bit bigger - it's not bad, it's just the way things are. If i were to try and live the simple life then things would get very simple... after the wife left and took the kids! It's all a journey so ask your journey people and work with their expectations of the whole permaculture/alternative/power down/sustainable experience - i've convinced the wife to use a hair straightener (120 watts) instead of a hairdryer (1700 watts) because larger inverters are more inefficient.

    I agree with Pebble - make a list of things to stay and what can go and start from there - good luck.
     
  10. hardworkinghippy

    hardworkinghippy Junior Member

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    If you're starting from scratch with a new home you have a wonderful opportunity to design an appropriate system !

    My first tip is - as Len says a dual system ie. Wind (If your site has wind) and solar - plus a water turbine if you're really lucky.

    My second tip is to position your panels somewhere where you can get at them to wipe the snow off !

    [​IMG]

    Sorry I'm not posting much but with the winter solstice and the snow we don't have much spare energy ! ;-)
     

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