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jwy224 avatar image
jwy224 asked

Using CTs to back-feed main panel have unwanted grid feed.

Hello,

I have been on quite an adventure with my new Victron setup. I purchased two Quattro 3000VA 48V inverters, the battery shunt, Cerbo, and two MPPTs—all from Victron. I have configured this as a 240V split-phase system. Initially, I purchased a Victron Energy Meter VM-3p75ct, only to realize it wouldn't fit the American grid-in cables. This was disappointing. I then purchased a Carlo Gavazzi EM 530, which works perfectly with the American grid wires. Now, I can monitor all the energy being pulled into my house, including the AC loads connected to the AC-Out of my setup. My solar system is performing well and feeding into my setup.

However, this is where the problem lies. I want to keep back-feeding power from my solar system to my main breaker box to help with loads, but I don't want to feed power back to the grid. I do not have an interconnection agreement with the power companies and don't want to send power back to them. I have searched extensively online and found others facing the same issue, but no solutions.

I am wondering if anyone has a solution or can suggest a method with the above setup to achieve the desired effect I am looking for. I am trying to avoid having to install a separate breaker panel for just the critical loads.

Thank you


victron
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6 Answers
sean avatar image
sean answered ·

Are you running ESS ?

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jwy224 avatar image
jwy224 answered ·

Yes I am running ESS

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sean avatar image
sean answered ·

Zero grid feedback and grid use is not possible, primarily due to the speed at which inverters ramp up and down in response to load changes. Grid usage and export will be minimal but will not be zero.

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jwy224 avatar image
jwy224 answered ·

Its not really minimal, over 1kw per day. I was hoping for much less.

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sharpener avatar image sharpener commented ·
Many ppl set the grid balance to 50W export as this minimises imports during the inevitable load fluctuations. This corresponds to 1.2kWh over 24 hours. Unless your supply company have a way of detecting this it is nothing to worry about.


If you set it to less you may get the aggregate down closer to zero but it may be at the expense of some level of parasitic import which will leave you no better off.



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jwy224 avatar image jwy224 sharpener commented ·

Thank you for your response. By grid balance you are referring to "Grid Set Point" correct? I understand what you are saying, this is my first month of "back feeding the grid anything" So I was a bit concerned with the 1.2kWh. I have a regular digital meter outside my house. I have noticed when I am feeding back the little bars go backwards. I guess I will find out at the end of the month if they can detect it. I would like to think not as I do pull more then my solar produces. My house uses a lot of power, around 80kWh a day. I can produce half that with solar.

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sharpener avatar image sharpener jwy224 commented ·
If there is anything that physically goes backwards I think you must have an old analogue meter. In which case you will be getting credit at the import rate for any export so you are better off than most.


Provided you continue to use twice what you produce they will not have any way of detecting it unless it is noticeably going backwards when they come to read the meter. At the worst they will change it for one that has a ratchet so it cannot do that.
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sean avatar image
sean answered ·

I assume you mean 1kWh ?

Have you adjusted the set point ?

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jwy224 answered ·

Yes 1kWh.

I have played around with many settings, including the grid set point.

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