Limiting current from grid to alternate sources

Discussion in 'The Projects Forum' started by Ruben Mathew, Aug 1, 2016.

  1. Ruben Mathew

    Thread Starter New Member

    Aug 1, 2016
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    0
    Hi,
    I have been tinkering with grid-tie A/C micro inverters, and we have a huge power problem, with charges running to tens of thousands. Micro inverters require power from the grid for activation, simply to protect the line workers, so if the gird is down the micro inverter switches off. I wanted to reduce my power bill so I wanted something that could allow AC voltage to remain the same while reducing current flow to the least possible from the grid to power on the inverters.

    I have worked on a couple of solutions, but I'm not happy with the end result, one was to be totally off-grid, which requires another pure sine wave inverter to continuously work off batteries to produce the pure sine wave, and the micro inverters will add the additional power required to run application, while a charge controller with charge the batteries.

    I have about 1800w (600w x 3) micro inverters with same capacity panels. If I add a 600w pure sine wave inverter with batteries, I should get a usable 2.4kw system (1800+600, at-least in theory).

    I want to know if there is someway I could use a direct power line from the grid to be connected to the micro inverter with least amp drawn to keep it functional but draw power from the 1.8kwa produced to run local appliances without tapping from the grid ? This will mean some sort of 3 way junction, where the input grid input will be limited and maximum power required drawn first from the solar grid tie inverters and then maybe very little from grid.

    TIA for any help in this matter :)

    Best Regards,
    Ruben.
     
  2. hp1729

    Well-Known Member

    Nov 23, 2015
    1,964
    219
    Are the sine waves syncronized?
     
  3. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,041
    1,670
    Charges of what running to tens of thousands of what? o_O

    Grid tie inverters do not work with solid state power inverter sources, sine wave or otherwise.

    It's a fruitless endeavor to try and make them work together being a grid tie inverter is trying to push power back against its source and a power inverter is not able to sink power being pushed back to it. At best nothing happens at worst they fight each other until one burns the other out.

    If you need more off grid inverter power capacity you need to use a bigger power inverter. It's a 'correct tool for the job' type of thing and grid tie inverters are not designed to work as supplementary units to a dedicated power inverter. If you are lucky and the load is in an ideal condition they may work with a power inverter to some degree but largely it's just a pure luck situation.

    Also, linemen getting electrocuted by back feeding in modern times is largely a myth.

    Any properly trained and employed lineman knows to never work on a HV line without at minimal solidly grounding it to a dead short at one or more points. It's one of their top rules and so readily practiced it's not really even an arguable 'what if' scenario.
    They don't work on a downed power line until it's confirmed to be both disconnected from both ends plus grounded out period.
     
    Last edited: Aug 15, 2016
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