Grid tie with batteries

Discussion in 'Connecting to the Grid' started by SBecker600, Nov 10, 2012.

  1. I wanted to run an idea past you guys. My rv has 430 watts solar through a rogue tech mppt charge controller into 6 golf cart batteries and i have a chinook 200 i recenlty purchased attached to a folding bumper tower. Any way i would like to gid tie the system in the winter when the rv is not in use so i thought of attatching a c60 in diversion mode to a wind sun g 600watt with 600 watts of dump resistors. When the batteries are topped off the diversion kicks all the available power to the sun g and if the grid goes down the resistors take on the load. Any thoughts on this idea would be appreciated.
  2. leamywind1

    leamywind1 WindyNation Engineer

    Yes, that would work. I have done the same thing. I use a Mornigstar. Just make sure if the grid goes down the Sun G dump relay does not get over loaded with using the wrong dump coils. The relay is good for upto 16 amps. You may want to use a redundant relay trigger if the grid should go down to burn off the excess power along with the Sun G . I know the weak points are their dump relays at least for wind turbines:).
    Good luck
  3. Good info thanks ! I didnt know they could only handle 16 amps.
  4. Would the PWM Signal (rapid switching) of the Bump loadcontroller not harm the GTI or reduce its efficiency ?

    I would keen to know , cause this could be a nice idea in some countries in Europe to export surplus and harvest FiT payments ....

    if i use a Gti without a Dump control inbuilt , can i run a dump element in parallel , that just and only kicks in ,when Grid inverter kicks out ? What do i need

    Thanks Billi
  5. leamywind1

    leamywind1 WindyNation Engineer

    Hello Bill,
    You would need a relay that is turned on at the volatge you want to dump. I am not sure what a Bump load conroller is? Talk to Tom (forum member) as he has an external controller that dumps with his GTI's instead of using the internal GTI dump relay. I would assume you can try using a 48v dump coil in parallel and see what happens?
    You could also try using a few zener diodes to cotrol the voltage dumping? I can explain how to do that if you would like to PM on that. Some kind of PWM could be used but not a straight forward solar CC with PWM. You would have to use something more robust in handeling not only the amps but the wide volatge ranges.

    The other way is to use small betteries and tie them at 24v for a 10-30 GTI or 48v for a 22-60 GTI. The batteries could be used as a buffer but you would still need something to dump that load from when the batteries get to full.
    There are many ways to do this, your particular situtaion will dictate which way you want to go.

  6. Thanks Larry :)

    Sorry for the "bump load controller " , sh"te spelling happens , I meant Dump load controller ,

    My straight question was , "Can i attach a GTI to the Dump load controller instead of a heating element ?"

    Sure , perhaps i should try it myself
  7. TomT

    TomT WindyNation Engineer

  8. :) Thanks
  9. leamywind1

    leamywind1 WindyNation Engineer

    If you tie just the GTI to the dump load controller and the grid goes down you still need a dump coil attached to the end load or your turbine will keep spinning. This can be done if you use a wind rated GTI and hook a dump coil to the dump controller. That is what i do. I use a morningstar 45 amp CC with PWM. I have a GTI 250w (wind rated WDL) tied to it and use the dump load controler off the GTI for the dumping incase the grid goes down. I only dump about 100 watts or so at 14v and I have a 200w dump load ressistor on it. This is off my battery bank that has solar only. I need a second CC or bigger if i were to run my wind into the bank too as the 45a CC is not enough load to hold down 4 turbines at once. You have to figure out your amp draw off the GTI dump relay as it is only good for 16 amps. 16 amps at 13v is only 208 watts and that is maxing out the dump relay in the China GTI.

    As far as I can see no matter what your end result is, it (Turbine) must be protected during a grid failure with some kind of ressistive load. Even UL inverters for wind have a dump coils as the end result.

    I hope this helps:)
  10. Thanks Leamy , its not for me personal , but for others , i am helping out ,
    Many offgrid inverters have a programmable Aux relays , that could jump in , just in case the GTI fails and Dump power

    i found a interesting charge controller called "Coleman Air C440-HVM Controller" that has a feature called "Extended Diversion Mode -- EDM " , that can extend the time the GTI is running in Diversion control
  11. leamywind1

    leamywind1 WindyNation Engineer

    OK well good luck and good info. I am familuar with that CC. Not so sure it is really is going to handle 440 amps though looking at the internals. Please let use know how that one does for you.
  12. Thats true 440 Amps are not believable:rolleyes:, still , i am basically searching for a device that switches on a Grit tie inverter , when batteries are getting full , and i am not talking about small GTi with an inbuilt dump ....

    Would be great to know , if a Morningstar Tristar in Diversion load could power a say 3000 watt GTI as a Dump idea , and if the PWM signal could/will harn the GTI

    Sure , its my go now, to find out ...
  13. leamywind1

    leamywind1 WindyNation Engineer

    If you want to dump 3000 watts the you would need a a CC rated for that. I think morning star is like 60 amps max. (not sure if they have a bigger model). Outback is 80. You could check out the Outback Classic too. You may be able to do some math to get your answer then look for a CC that can do that.
    Just some quick math:
    Dumping at 14vdc would be dumping 225 amps or 3150 in watts. Dumping at 26vdc would be like 125 amps or 3120 in watts. Running at a 48vdc system and dumping at 50vdc would be like 60 amps or 3kw.
    I do not think the PWM will hurt the GTI as it's MPPT will lock on to what ever it recieves but again uncharted waters and great questions to be answered..

    Does that help?:)
  14. It does , i was thinking of 48 Volt , cause there are big WindGrit tie inverters available that start working under 50 Volt ....

    But sure , perhaps better to try and test with a small "cheapish" inverter first
  15. leamywind1

    leamywind1 WindyNation Engineer

    Hi Billi,
    Great glad to help if I can. I am not to sure there are many choices (non Chinese) for under 50VDC GT inverters, UL anyway. I know Auroa is one but i am not sure if it would yeild good watts at 50-55vdc tops condiering batery clamping. If you know of any others (that are not Chinese) please post. Ginlong (China and UL listed) says 30-750VDC but we contacted them and their 30vdc input is a bunch of BS. No power is really made until about 100 vdc for a wind turbine. UGH!! If you are speaking of bigger grid tie inverters from China then yes, you are right, there are many. A few of them actually have the displays on the front (W,V,A) and a USB coonection to your PC too.
    Good luck with your system and please keep us posted.:)

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