New Hydro Electric Project

Discussion in 'The Projects Forum' started by anav686, Mar 27, 2009.

  1. anav686

    Thread Starter New Member

    Mar 27, 2009
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    I have a source of water on my property that is going to spin 4 water wheels at high RPM (approx 1000 RPM). I want to attach 8 car alternators to these wheels. All alternators will be identical and should spin in unison. Here are my questions:

    Can I connect all 8 alternators in parallel (approx current would be 12VDC at 800 amps) and then run that current into two pure sine DC/AC 4000 watt inverters?

    What are the problems associated with connecting DC alternators in parallel?

    As an alternative, should I individually connect all 8 alternators to 8 inverters and if so, how do I connect the inverters together? Any help I can get with this I really appreciate. Thanks.
     
  2. mack2k

    New Member

    Mar 26, 2009
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    I don't know about the hookup, but I was wondering why you don't use one big wheel to turn a big generator? there are some need setups on utube..
     
  3. recca02

    Senior Member

    Apr 2, 2007
    1,211
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    I think this is a better idea. However voltages of each generators should be same. Thus if they are of the same type, speed of rotation should be same. Make sure you get the polarities right ( positive connected to positive and negative to negative).

    How do you plan to use to inverters after connecting the generators in parallel?

    My advice would be to go with AC generators instead of DC ones.
     
  4. anav686

    Thread Starter New Member

    Mar 27, 2009
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    I don't have a lot of flexability with the physical design. I am stuck with 4 wheels turning fast giving me a free source of mechanical energy that I want to harness. AC generators are too big for what I am doing. Car alternators are just the right size.

    I want to power my 2500 sqft house with the power and tie it into the grid. The alternators need to be tied together and then the final leads go to the two inverters. Those two inverters will be tied together and connected to my sub-panel in my house.

    Can I parallel these identical alternators together if they are all spinning at the same RPM? I would like to parallel 4 alternators to one inverter and 4 alternators to another inverter. Then tie both inverters to get one stream of 8kw 120VAC power into my sub-panel.

    Is this feasable?

    Or do I need to get eight 1000 watt, pure sine inverters and connect all eight 12 VDC / 100 Amp alternators to each individual inverter, then connect all the inverters together?
     
  5. recca02

    Senior Member

    Apr 2, 2007
    1,211
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    Paralleling of inverters is what I'm more concerned about, as frequency and phase differences come into play. I'm also not sure if they can be manipulated(easily) for synchronization . Can you not go with one inverter?
     
  6. b.shahvir

    Active Member

    Jan 6, 2009
    444
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    :) Hi, car alternators are AC generators which use diode rectifier to convert o/p AC voltage to DC. Disconnect the rectifier ckt. and connect the alternators in parallel.....this way you can elliminate the need of an inverter. (a very ambitious project i must say!! ;))
     
  7. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    Check with your local inspectors to be sure, but you will need to connect the grid-tie inverter output (via disconnect) to the service entrance conductors (instead of to any sub-panel).

    Yes.

    I'm not certain two grid-tie inverters will play nice together. During the first five minutes of operation, the grid tie inverters are required to insure grid power is stable. They will attempt to pull the line frequency (making it nearly impossible to fool them with a generator). If they both start pulling different ways at the same time, they just might shut each other down. Use one single grid-tie inverter instead. (Yes, it will require more searching on your part to find a big one. You'll need to send e-mails to manufacturers instead of relying on search engines or shopping bots.)

    Depends on your flow, your head, your turbines, and your alternators. Do you have numbers for any of those?

    One thing you have not considered:

    Grid-tie inverters must drop out if the grid goes offline. (Bimodal inverters are an exception, but based on what you've said I don't think you are using those.) Alternators must have a load at all times. How will you load your alternators during a grid outage?
     
  8. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    They want to tie to the grid. Do we know what frequency those alternators will run at? 2 or 3 times crankshaft speed is typical. Most automotive alternaters are three phase.

    A listed inverter is needed if one wants to tie to the grid.
     
    Last edited: Mar 29, 2009
  9. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    In my opinon this is not a good DIY project, especially the part about tying to your utilities grid. If you were just generating DC power to heat water or power your local lighting requirements that is one thing you could play with just like a lot of the DIY wind generators projects.

    Once you wish to tie to the utilities grid I suspect it has to be done with preapproved and inspected equipment and subject to a lot of different local utility and goverment regulations. I'm sure there must be more speciality forums that could give you better specific recommendations about what works, what doesn't and what is practical.

    Lefty
     
  10. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    Absolutely! The best source of advice and help in matters of this nature is the friendly local electrical inspector. Those folk really like it when they get called with questions before a project. They enjoy helping people be safe.
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    My earlier assessment was in error. I have learned that grid tie inverters are very sophisticated indeed. They are able to recognize other grid-tie inverters. Grid-tie inverters can indeed be used in parallel - they don't even have to be from the same manufacturer.
     
  12. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    What is the cost of a grid-tie inverter compared to a single dwelling inverter?

    8kW isn't that much, and could take an extremely long ltime to pay for itself. Especially considering the cost of alternator rebuilds/replacements from running 24/7 on full load (typical car alternator has a lifetime of about 2,500 hrs).
     
  13. anav686

    Thread Starter New Member

    Mar 27, 2009
    3
    0
    Thanks for all the help guys. This has been enlightening.
     
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