Announcement

Collapse
No announcement yet.

Hoping someone could help...

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

  • #16
    Originally posted by gjohn View Post
    yeah - ...... TOTAL solar power is what is sent to meter not net. obviously, that can be done in different ways and the meter needs to see 4Kw coming in and we are good. we also dont have peak-power differentials like in California (we are in MA). I do understand the physics (simple kirchoff's law in this case) thanks for trying to help and your ideas.
    First off power is not sent, it flows to the loads. For solar power generated behind the meter the grid acts like a load. Physics determines that any solar generated will flow to the nearest load then to the grid which is what happens.The meter will only see the Net because the load is behind the same meter that the solar is behind. That load is closer than the load that the grid presents.

    Forget the transfer switch for the moment. Also, I think Kirchoffs law is confusing the issue. Do you understand why the meter only sees the net? You would have to take the load somewhere else, for example behind a separate meter, and then all your production will be seen by your main meter.

    The fundamental question is not really about how to set up a transfer switch, instead is is, how l get your utility meter to measure production without subtracting load? Is that not the issue? You as much said it when you said, "the meter needs to see 4Kw coming in and we are good."

    If one can not do it with a simple circuit behind the meter, a transfer switch will not make it happen. I have no need to convince you if you do not want to see it that way. My comments are intended to be informative to the thousands of lurkers that may gain something from this conversation. I hope someone else chimes in with a point of view that clarifies it better than I have been able.
    Last edited by Ampster; 12-29-2019, 10:40 PM.
    9 kW solar, 42kWh LFP storage. EV owner since 2012

    Comment


    • #17
      Not sure if this helps but I am in MA also, have a StorEdge, a LG Chem battery which I use only for backup, and a subpanel for critical loads fed when the grid goes down by the battery. The transfer switch is standard with the basic StorEdge unit and SE inverter. There are two Eversource installed meters. One for netmetering, and a separate one measuring total output that is used to calculate MA SMART credits. Here's a link to some photos which show the configuration (there is also a combiner box before the total output meter for some panels with microinverters separate from the Storedge/SE which you can ignore): https://1drv.ms/a/s!AurfEsR2BLA4geVLqD6qLmCZeEEYPw
      Last edited by willow1; 12-30-2019, 01:11 PM.

      Comment


      • #18
        Originally posted by willow1 View Post
        Not sure if this helps but I am in MA also, have a StorEdge, a LG Chem battery which I use only for backup, and a subpanel for critical loads fed when the grid goes down by the battery. The transfer switch is standard with the basic StorEdge unit and SE inverter. There are two Eversource installed meters. One for netmetering, and a separate one measuring total output that is used to calculate MA SMART credits. Here's a link to some photos which show the configuration (there is also a combiner box before the total output meter for some panels with microinverters separate from the Storedge/SE which you can ignore): https://1drv.ms/a/s!AurfEsR2BLA4geVLqD6qLmCZeEEYPw
        Yes that helps. Perhaps that is what the OP means when he says he gets credits. You are probably talking about SREC credits and apparently your utility or whomever you sell the SRECs to (presumably Eversource) installs their own meters, one for production and one for net metering. I think the OP needs to get another meter installed or determine if the revenue grade meter in the StorEdge will suffice. The operative answer most likely will come from his power company not from this board.
        9 kW solar, 42kWh LFP storage. EV owner since 2012

        Comment


        • #19
          Originally posted by willow1 View Post
          Not sure if this helps but I am in MA also, have a StorEdge, a LG Chem battery which I use only for backup, and a subpanel for critical loads fed when the grid goes down by the battery.
          @Willow1 - your experience in this case is immensely helpful. Thank you very much for making the effort to send those pictures too. I do recognize the inbuilt transfer switch for battery kick-on purposes. Looking at your wiring it looks like it may be possible that my electrician did not wire the way yours is, which may be putting me in this predicament ( but not yet sure). There is a small possibility that you might also have the same issue i have (see #3 below) ? Could you please help me figure out a few things:
          1. which of the meter is the total solar measurement -i assume the grey NOT the black? and is that meter installed before the connections go to solar edge? I assume it is after.
          2. on your StoreEdge picture, which line is the critical load and which one is the main panel load?
          3. On a monthly basis does the reading from your TOTAL meter approximately equals what is reported by Solaredge? If not, could you please quote some numbers for one or two months, if possible?
          4. is your crtical load panel put on a seperate fuze box that is only powered by Solaredge? ie there is only one incoming connection to that panel, and that is from Solaredge.
          thank you very much.

          Comment


          • #20
            gjohn, see below:
            1. which of the meter is the total solar measurement -i assume the grey NOT the black? and is that meter installed before the connections go to solar edge? I assume it is after.
            Yes, the meter second box from the left is the total output measurement. It is after the SE which feeds the combiner box (third from left) along with the the AC output from the Enphase microinverters.
            2. on your StoreEdge picture, which line is the critical load and which one is the main panel load?
            The critical load feed is the one on the right of the picture (lower of the two feeds to the right). The main panel AC feed is the feed on the left which then goes to the right of the picture on the top.
            3. On a monthly basis does the reading from your TOTAL meter approximately equals what is reported by Solaredge? If not, could you please quote some numbers for one or two months, if possible?
            Its a bit complicated given that that I have to add together the output from the SE monitoring as well as the output from the Enphase Envoy monitoring. In total though, they are roughly what is reported on the total output meter. There is a two month delay in the Eversource SMART billing / credits, but they do approximate what the SE and Envoy monitoring apps each report.
            4. is your crtical load panel put on a seperate fuze box that is only powered by Solaredge? ie there is only one incoming connection to that panel, and that is from Solaredge.
            The critical load sub panel and breakers are powered only by SE (from the battery) when the grid is down. If the grid is up, AC power is used from the PV or from the grid if not generating PV at the time. Here's a link to photos of the main / subpanel with the subpanel cover open and closed.
            https://1drv.ms/a/s!AurfEsR2BLA4geVO_2xvXBmoEdicEg
            Last edited by willow1; 12-30-2019, 05:59 PM.

            Comment


            • #21
              @Willow - that was superhelpful. So the grey meter, despite it being on the main panel load which ONLY supports the non-critical load (because you confirmed the subpanel supporting critical load is only supported by solaredge) is able to calculate the total production power. @Ampster /anyone: do you know how that happens ? In my mind that meter is only seeing the current (i) and meter-resistance(R) in that line of non-critical load and then using the "equivalent" of i*i*R to calculate power but is then ignoring the other subcircuit with the critical load from a physics standpoint.
              Originally posted by Ampster View Post

              Forget the transfer switch for the moment. Also, I think Kirchoffs law is confusing the issue. Do you understand why the meter only sees the net? You would have to take the load somewhere else, for example behind a separate meter, and then all your production will be seen by your main meter.

              .

              Comment


              • #22
                gjohn, think the critical loads are only fed from SE and the battery when the grid is down. When the grid is up, the main load or grid feeds these circuits (otherwise there would be no power to these circuits when there is no power being generated by the inverter, and the output to the main load would be reduced as well).

                Comment


                • #23
                  @willow -You could be right, and you may have indeed solved the problem that no one else so far did! - ie solaredge is normally allowing the grid powering the to power the critical-load subpanel fully, and hence the production meter will indeed calculate the power generated in full. I have not find any documentation yet on this front. I thought solaredge was splitting the PV to both critical and no-critical lines under normal circumstances. Anyone else has a different opinion? If not, i will tag this as solved. Thanks again Willow, that is indeed a fantastic pointer, which makes an ATS unnecessary for that reason in MA for solaredge (hope someone can confirm this for sure).

                  Comment


                  • #24
                    Originally posted by gjohn View Post
                    ..... @Ampster /anyone: do you know how that happens ? In my mind that meter is only seeing the current (i) and meter-resistance(R) in that line of non-critical load and then using the "equivalent" of i*i*R to calculate power but is then ignoring the other subcircuit with the critical load from a physics standpoint.

                    It is all about where the CTs are placed hat measure the current. SolarEdge uses internal CTs but it may also be able to use external CTs like my Outback Skybox can. I am glad the discussion has moved from whether a transfer switch will work to a discussion about how best to measure production.
                    Last edited by Ampster; 12-31-2019, 01:00 PM.
                    9 kW solar, 42kWh LFP storage. EV owner since 2012

                    Comment


                    • #25
                      Originally posted by gjohn View Post
                      @willow -You could be right, and you may have indeed solved the problem that no one else so far did! - ie solaredge is normally allowing the grid powering the to power the critical-load subpanel fully, and hence the production meter will indeed calculate the power generated in full. I have not find any documentation yet on this front. I thought solaredge was splitting the PV to both critical and no-critical lines under normal circumstances. Anyone else has a different opinion?
                      You were correct that the power from the SolarEdge was being split. It was not the SolarEdge that was splitting the current, rather the loads that were splitting the current. In the situation where there is generation that exceeds the load the grid presents as a load and the current from the inverter is split between the grid and the other loads behind the meter.That was being done after it leaves the SolarEdge inverter.
                      If you want to document it you can perform this simple test. Place a current clamp on the output from the SolarEdge and you will see that it should be the same as the production meter on the SolarEdge. Place the clamp on the legs after the meter and you will see that the result is Production less Consumption. In other words, the Net result of production less consumption.

                      I regret that I was able to articulate it as clearly as @willow but at least you are off the tangent of trying to solve the problem with a transfer switch..
                      9 kW solar, 42kWh LFP storage. EV owner since 2012

                      Comment


                      • #26
                        Originally posted by Ampster View Post
                        Place a current clamp on the output from the SolarEdge and you will see that it should be the same as the production meter on the SolarEdge.
                        ..
                        Thanks for that insight. which output? i assume the line from solar edge that goes to main panel? - remember there are two accessible "outputs" from solar edge: one that runs to main panel and another that runs to the sub-panel with critical load as Willow showed using his installation.

                        Comment


                        • #27
                          Either one. One should be your subpanel consumption, which might not be active unless you are on backup power. The other should be production. You could also try it on your service entrance and see net production.
                          Last edited by Ampster; 12-31-2019, 01:27 PM.
                          9 kW solar, 42kWh LFP storage. EV owner since 2012

                          Comment


                          • #28
                            Originally posted by Ampster View Post
                            Either one. One should be your subpanel consumption, which might not be active unless you are on backup power. The other should be production.
                            I dont see how your phrasing in this post is correct. If you look at what Willow sent, the subpanel is always active from solaredge because that is the critical load that has no other line connection to get power other than from one of the two output lines from solaredge, while the other non-critical circuit panel is directly connected to solaredge and the utility connection. And finally if the current in both the lines are the same, the power (I*V) in those lines also will be the same because the voltage is standard 120/240 and that means when the solar is producing just enough for all the house loads, that equates to the same amount of power utilized by both critical and no-critical loads which is absurd. the only explanation that is so far seem to make sense (your's is not yet making sense to me) is from willow who thinks the critical load subpanel is purely powerd by grid.


                            Comment


                            • #29
                              What did you find out when you put the clamps on? The point of my post was for you to observe the power coming from the SolarEdge inverter and compare that to the SolarEdge . Also observing the power going to the sub panel should give you some insight Don"t expect the load on the critical loads subpanel to be balanced. Each leg could be different, whereas the output of the SolarEdge should be balanced.

                              I may not understand your wiring. The only one I have seen is your hypothetical one withe the hypothetical transfer switch. I couldn't open the other one.
                              Last edited by Ampster; 12-31-2019, 06:26 PM.
                              9 kW solar, 42kWh LFP storage. EV owner since 2012

                              Comment


                              • #30
                                Originally posted by Ampster View Post
                                I may not understand your wiring. The only one I have seen is your hypothetical one withe the hypothetical transfer switch. I couldn't open
                                the other one.
                                this is the wiring diagram for Storeedge, that both me and willow have. in willow's case there is a production meter on the line going to load. What i still dont have total confirmation from this forum is if the critical load is fully powered by the grid or if the solaredge is combining the power from grid and PV and then realllocating the power to the critical load (backed-up) and noncritical load
                                https://www.solaredge.com/us/solutions/grid-backup#/. if the former, it is clear why the production meter will faithfully capture the total solar output. if the latter, no one has explained yet why the production meter will see the full PV output.

                                Comment

                                Working...
                                X