Design help with a off grid solar system.

Discussion in 'Energy' started by Lee-Mika, May 13, 2014.

  1. Lee-Mika

    Lee-Mika Active Member Premium Member

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    I'm planning an off grid solar system, but the problem is it needs to be economical maybe If I get lucky I could find some components used. But as it looks right now what I want to build is a 500- 1000 watt Pv array, with a 2000 watt inverter, Maybe a little larger. 60amp MPPT charge controller. The equipment has to be very reliable and cost effective. As this is a one shot build on a tropical Island. Not like I will have a job so I can just go out and buy new stuff or even upgrade. So does anyone have any help for on thins topic?
     
  2. stevo

    stevo Backyard Farmer Premium Member

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    I'm no expert, but i'll comment anyway :D

    Economical and cost effective aren't things that come to mind when I think about offgrid systems. What's your budget? How many batteries do you want/need?

    or what info are you after? Specific brand names or retailers?

    I think batteries are around $300 - $350 for 1 x 120AH?
    Panels, $250 for 200watts?

    So I don't think you need to spend $10,000 but you can easily spend $4000 - $7000

    The user @Scott Mac on here will have some better information
     
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  3. Lee-Mika

    Lee-Mika Active Member Premium Member

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    Hello, Stevo
    I found batteries in the Philippines, that can be gotten for about 11,000 pesos each, 200ah. The price is fair. I can also get PV panels at a fair price. But I can't get charge controllers, or inverters, at fair prices, they are 3 times higher than they should be. and to top that off the are all cheap Chinese made. which means even if they work they will not last more than a year. I figure the whole system will cost me about $3,000 dollars.

    I plan on using 4x 200ah batteries right now I may go to 6x 200ah, as we suffer long periods of rain. But I have started thinking about a water wheel, there is a stream but it does run all year. but it has been running for the last six months. from what her during the dry season it dries up, so maybe I can find a 500w permanent magnet generator, that I can hook up to a water wheel. during the rainy season to charge batteries. That may cover the power issue.
     
  4. stevo

    stevo Backyard Farmer Premium Member

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    yeah I'd get as much battery power as possible and buy them all at the same time. But on the other hand, it's a lot of money to mainly run a fridge.

    I see in your other thread you mention 85watt fridge and 45watt Tv. My new fridge varies from 100watts to 30watts when running and my little offgrid system runs it, but starts getting low after a couple of days. If you're really struggling for power, you can keep a look out for a 12v camping fridge and 12v TV. They will make a huge difference to your power consumption, even though they will cost more to start with.
     
  5. Lee-Mika

    Lee-Mika Active Member Premium Member

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    I have been wondering about this voltage issue as well. but if I buy 12v the system has to 12v. But 12x800=9,600 watts, but if I wire it 24x800= 19,200 watts So I am not so sure that 12v would be of any real help..
     
  6. stevo

    stevo Backyard Farmer Premium Member

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    I'm not sure what these calculations are...
    I think...

    If you're just using normal 110v or 240v appliances then you'd go 24v or 48v.

    If you can't make a big enough system to run your 110v/240v appliances then a small 12v system with 12v appliances might get you by.
     
    Last edited: May 16, 2014
  7. Lee-Mika

    Lee-Mika Active Member Premium Member

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    Hello Stevo
    We use 240v 60hz in the Philippines. Not sure if about running 12v on special systems it may have to happen that way. When Chinese new years comes next year I will spend time on the land and figure out where every thing has to go..
     
  8. Steve

    Steve Valued Member Premium Member

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    I'm interested in where this ends up and what the final solution is. I like the idea of a water-wheel.
    One tv show I saw once which was about Alaska they travelled to a remote part of a river to fish and they used an old washing machine converted into a water wheel as their only power. Pretty cool I thought.
     
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  9. Lee-Mika

    Lee-Mika Active Member Premium Member

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    Well the steam seems to me to run most of the year and as there are some many cloudy days. I was thinking that if could find a low RMP generator I could, create enough wattage to connect to a charge controller, allow it to charge the batteries during cloudy days. Well not need anything very big to do it. 500w 24v or 12v motor would do just prefect.
     
  10. Tim C

    Tim C Two heads are better than one Premium Member GOLD

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    The 2 wind generators I have are made from dc treadmill motors.(From the dump shop-$10 each) One is brushed and the other brushless. From memory they are 100 vdc rated at 2500rpm. This just means that for 12 or 24v you run it slower. My controller is a Coleman-air from USA. I think it was about $100AU I made the mistake of buying carbon composite wind blades. They would only turn the little gennies in a hurricane. I replaced them with plywood ceiling fan blades for a much better result.
    These dc motors could be used for a water mill. The ones I have seen are set up on floats cabled either side, so they can rise or fall with the water level. Flat, multi-ribbed belt drive would create the least resistance whilst negating slippage under load.
    A 12-24 volt dc motor would need to run at high speed, therefore have more wear/less service life.
    I hope this reply was helpful. 2012-11-26 18.37.59.jpg 2012-11-26 18.40.10.jpg
    My inverter is a sinewave 3000/6000 watt. $220AU Ebay auction. Yes Chinese-made. Yes the first one caught fire! But the warranty replacement has been fine. 2011-02-19 22.02.28.jpg
     
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