Announcement

Collapse
No announcement yet.

Can a grid tied Skybox supply power to the main panel without export?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Can a grid tied Skybox supply power to the main panel without export?

    I posted this over on the Outback power user forums but didn't get a response. I guess its not too active over there.


    I have been reading a little about this but I haven't found a clear answer.

    I don't want to export because it is not cost effective with my electric coop as they charge $30 just to do net metering, plus I'll have to get a $1m liability policy for probably another $50/month.

    Most of my circuits are in my critical loads subpanel, but altogether they only draw about 500 watts during most of the day, usually less. So my 5kw of panels are only going to supply 2-4kwh during the day. So until I get some batteries installed I will be wasting a lot of excess production unless I can supply some of the loads in my main panel.

    My AC unit, electric dryer, and hot water heater are all that is in the main panel but they are most of our usage.

    When I ordered the skybox the applications engineer told me I could definitely support the additional main panel loads with Skybox, but he didn't tell me I'd probably have to use CT's to set that up.

    So my question is, can it be done this way, and how do I set it up? I planned on ordering the outback power CT's to set it up. I know the documentation says that if the CTs are installed you can use it for export control. "Many AC profiles allow the SkyBox to support the main panel (non-backup) loads (F to C) without selling power" But I'm not sure exactly which AC profile to use and how to set it up yet.

    I did just order the Outback 200 amp CT today.


    Thanks for any help!

  • #2
    I posted an answer there and a link to a tech support person. You can PM them on that forum. I did notice that someone else had posted and I also linked to another thread which might specifically answer part of your question.
    9 kW solar. Driving EVs since 2012

    Comment


    • #3
      If you are in the US and have 240v, your power company will probably detect back feed on one the legs. you might be pulling 2 amps on one leg and back feeding 2 amps on the other leg. perhaps a auto transformer would balance this. with the old style mechanical meters you could get away with this.

      Comment


      • #4
        Originally posted by RottenMutt View Post
        If you are in the US and have 240v, your power company will probably detect back feed on one the legs. you might be pulling 2 amps on one leg and back feeding 2 amps on the other leg..
        What would cause a split phase inverter like a Skybox to export unbalanced production when it was configured for zero export?
        I am not sure why the example you gave would be an issue since I am not aware of any smart meters that report data for each leg separately.
        Last edited by Ampster; 02-27-2021, 09:48 PM.
        9 kW solar. Driving EVs since 2012

        Comment


        • #5
          Originally posted by RottenMutt View Post
          If you are in the US and have 240v, your power company will probably detect back feed on one the legs. you might be pulling 2 amps on one leg and back feeding 2 amps on the other leg. perhaps a auto transformer would balance this. with the old style mechanical meters you could get away with this.
          I would hope not. That would be a safety issue I would think. Although I assume it would have protection built in like other grid tie inverters when the grid goes down.

          I have talked to the poco engineer and he told me as long as I didn’t export I didn’t need an agreement with them. Their agreement is not good, they require a $30/month fee just to net meter. And $1m liability insurance.

          Comment


          • #6
            Originally posted by df0rster View Post
            I would hope not. That would be a safety issue I would think. Although I assume it would have protection built in like other grid tie inverters when the grid goes down.
            ............
            I am sure it is not a problem, especially when the grid goes down because the relay on the AC in opens for air gap isolation. I can hear it click when I drop the grid for a test.
            I completely understand and agree with your decision about the economics. Did you notice the thread on the Outback Forum where the tech talked about the slosh between the grid? I have noticed the same thing and it is only for a few seconds and varies from small import to equally small export. The Skybox algorithm is much faster than the typical measuring periods of most Power Company accounting systems. To even detect anything they would have to come out and attach very sensitive test equipment.
            9 kW solar. Driving EVs since 2012

            Comment


            • #7
              My meter detects back feed and notifies my utility. I set by enphase Profile to not export and the meter did detect it!
              Last edited by RottenMutt; 03-01-2021, 06:41 PM.

              Comment


              • #8
                Originally posted by RottenMutt View Post
                My meter detects back feed and notifies my utility. I set by enphase Profile to not export and the meter did detect it!
                What did your utility say when they were notified? Did you get charged? What utility and what location? What did the meter detect after you set the Enphase to non export?
                Last edited by Ampster; 03-02-2021, 08:16 AM.
                9 kW solar. Driving EVs since 2012

                Comment


                • #9
                  Originally posted by RottenMutt View Post
                  My meter detects back feed and notifies my utility. I set by enphase Profile to not export and the meter did detect it!
                  I’m interested to know more details as well. I spoke directly with the poco engineer and he said as long as you don’t export it wouldn’t be a problem not to have an agreement. But I don’t know if they consider tiny back feed fluctuations exporting.

                  Is there a setting on grid tie inverters where you could not only restrict export, but specify some small amount of power is always flowing from the grid. Maybe your enphase inverters are causing your meter to stop which is triggering some alert with your poco.

                  Comment


                  • #10
                    I called on status of my application and they asked me to turn off my system. Ive since turned my system back on during freezageton and saw a code pop up on the meter (CBFD current back feed detected). They had me revise my application to add the output of my power walls as well, and congratulated my on being there largest system, 240 amps.
                    try-county electric is my utility. My electricity provider, Brazos, claimed bankruptcy yesterday after getting 1.9 billion bill from ERCOT.
                    Last edited by RottenMutt; 03-02-2021, 06:31 PM.

                    Comment

                    Working...
                    X