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  • Zero feed into grid with Enphase?

    I will be installing solar power at my house in Spain later this year. I am as yet notfully decided on what system I will use. String or micro inverters.
    My Question is about Micro inverters specifically.
    The requirement in Spain is that there is to be no feed from household solar power into the grid system.
    So I require a zero export device. I assume this is possible with micro inverters?
    I have gained a little information regarding Enphase micro inverters (specifically the S series).
    I assume i would be using the Enphase envoy to achieve zero export to the grid?
    Anyway, if anyone has some information regarding any manufacturer of micro inverters that facilitates zero export to the grid, I would appreciate it.
    I have found loads of information regarding string inverters with facility for zero grid export.

    C.R.J.

  • #2
    Originally posted by C.R.J. View Post
    I will be installing solar power at my house in Spain later this year. I am as yet notfully decided on what system I will use. String or micro inverters.
    My Question is about Micro inverters specifically.
    The requirement in Spain is that there is to be no feed from household solar power into the grid system.
    So I require a zero export device. I assume this is possible with micro inverters?
    I have gained a little information regarding Enphase micro inverters (specifically the S series).
    I assume i would be using the Enphase envoy to achieve zero export to the grid?
    Anyway, if anyone has some information regarding any manufacturer of micro inverters that facilitates zero export to the grid, I would appreciate it.
    I have found loads of information regarding string inverters with facility for zero grid export.

    C.R.J.
    When using micro inverters, a zero export setting requires that there be an interface point between the house (loads plus generation) and the grid which can detect the direction and magnitude of power flow. For a string inverter that requires a power measuring interface located somewhere other than at the string inverter itself.
    A hybrid string inverter can do this easily since its off grid mode requires that the house loads be supplied through a transfer switch build into the inverter. A pure grid tie inverter will need an additional piece of hardware.
    But for micro inverters it requires an extra piece of hardware as well as a management platform that can send power throttling commands to all of the micro inverters and coordinate them.
    I do not know of any such system at the moment.
    If you have a good reason for not wanting to use a pure string inverter, then a string inverter plus optimizer integrated system like SolarEdge may be your next choice.
    Or a string inverter with zero backfeed capability and independent optimizers on the panels.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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    • #3
      My situation is exactly the same as C.R.J.'s, even the location: Spain. Where the sun shines always, but the government makes it very difficult for solar people.

      I'd prefer a system made up of Enphase M250 inverters; the newer ones (IQ and S280) are not yet certified for Europe.

      I have also tried to find out what Enphase's Envoy-S (standard version and the metered version) can do, but the online documentation is not that extensive. I assumed too that the Envoy is capable of controlling the power output of your system, but I now think it cannot do that. It's just for monitoring. I mailed Enphase with an enquiry a week ago, but still no reply.

      Zero feedback to the grid should be very easy with these micro inverters: you don't need to exactly control the actual output of each inverter, you could simply switch them off one by one, so per 250W, if you produce more power than you use. If you're using less than 250W the last inverter is switched off, and you'd use the grid.

      If the Envoy cannot do this for you it could be that it is not difficult to achieve with some diy: these inverters are very good at detecting if the grid is still there, and do a (very) quick shutdown if it is not. So why not hook each of them them up with a controllable net-switch-relay per inverter, and monitor production and power usage with a bit of hardware, and switch off inverters that you don't need? (I can program Arduino..)

      Enphase has an API (see https://developer.enphase.com ) so perhaps the Envoy can already get you the information on power generation and usage. (Studying that now.)

      I really like these micro-inverters too. It enables me to start small, and extend... And, they live longer than a string inverter too.

      Problem here in Spain could be to get a system like this registered and certified.

      rick
      Last edited by rickj; 07-01-2017, 10:15 AM.

      Comment


      • #4
        Originally posted by rickj View Post
        Enphase has an API (see https://developer.enphase.com ) so perhaps the Envoy can already get you the information on power generation and usage. (Studying that now.)
        Indeed you can access information in your local Envoy. It's even in the manual (https://enphase.com/sites/default/fi...al_US_EN_2.pdf).
        Connection with a web browser to your local Envoy-S is described in page 31.

        On page 6 it says "When used with Enphase devices, the Envoy-S can control grid management functions and monitor PV production and site consumption. When used with non-Enphase PV systems, it can collect production and consumption data, but does not control grid management functions." - implying that there are grid management functions, in addition to monitoring production and consumption.

        Anyone with information on those management functions?

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        • #5
          Originally posted by inetdog View Post

          ...But for micro inverters it requires an extra piece of hardware as well as a management platform that can send power throttling commands to all of the micro inverters and coordinate them.
          I do not know of any such system at the moment.
          To be a bit more explicit: Enphase has the Envoy system. A metered version to measure production and consumption with current transformers, and an unmetered version. From the documentation I think it is implied that the Envoy can throttle production. The docs also speak of "grid profiles" that are different for each country/region. Don't know yet if they can do a zero feedback profile for Spain.

          What else but Envoy adapts production if panels are shaded, which is a an Enphase feature? Or does the micro-inverter detect that itself, and shuts itself down?

          rick
          Last edited by rickj; 07-02-2017, 04:22 AM. Reason: Small textual change.

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          • #6
            Enphase - Zero Export using S-Series MicroInverters and Envoy-S Metered Gateway
            Hawaii, USA currently prohibits new PV Export into the Grid, too.
            It is called CSS - Consumer Self Support.
            If you create a tremendous amount of excess PV energy then maybe recharge Enphase AC Battery during the day and discharge at night?

            https://enphase.com/sites/default/fi...pply-EN-US.pdf
            Last edited by NEOH; 07-03-2017, 12:08 AM.

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            • #7
              Solar Edge - Zero Export

              https://www.solaredge.com/sites/defa...ation_note.pdf
              Last edited by NEOH; 07-03-2017, 12:08 AM.

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              • #8
                ZED - Zero Export Device ...

                http://www.zeroexportdevices.com/residential

                http://www.zeroexportdevices.com/wp-...e-2016-A4F.pdf
                Last edited by NEOH; 07-02-2017, 11:59 PM.

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                • #9
                  Fronius - Zero Export feature ...

                  https://www3.fronius.com/cps/rde/xbc...8_snapshot.pdf

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                  • #10
                    Originally posted by NEOH View Post
                    Enphase - Zero Export using S-Series MicroInverters and Envoy-S Metered Gateway
                    Hawaii, USA currently prohibits new PV Export into the Grid, too.
                    It is called CSS - Consumer Self Support.
                    If you create a tremendous amount of excess PV energy then maybe recharge Enphase AC Battery during the day and discharge at night?

                    https://enphase.com/sites/default/fi...pply-EN-US.pdf
                    Thank you for that info! Do you know if the "intelligence" to do this is in the Envoy-S or in the micro-inverters? The S280 is not available in Europe, there only is a 60Hz version for the USA market. Though in Australia, and only there, there is an S270: https://enphase.com/sites/default/fi...DS-EN-AU_0.pdf

                    If the intelligence is in the Envoy-S this can work with M250 too.

                    (Funny, in the tech brief pdf you linked they show a 240V grid

                    Comment


                    • #11
                      Thank you for your responses, inetdog, rickj, NEOH,
                      The S series micro inverters with the envoy metered gateway look as thought they fulfill the requirements for zero export if I install a solar system with micro inverters.
                      I currently cannot source them, or support for them, in Spain. However I have found a supplier in Germany if I go that route.

                      NEOH. I did look at that exact Fronius system. That is what I am considering using, if i do not go the micro inverter route.
                      One of the reasons for looking at installing micro inverters was because my roof is flat and easily accessible. Therefore changing micro inverters or maintenance, should i need to do so, is straightforward.
                      The standard string inverter would be difficult to place in a cool area near to both the panels and the main power panel for my house.
                      I will not have shading issues on my roof, but there is only space for 7 panels. (which is ok for now). However when I extend the system, i need to use a different location for the extra panels, and there will be shading issues. With the micro inverters, 90% of the equipment will be on the roof out of sight. I also prefer running A.C. around my property and not high voltage D.C.
                      The only thing putting me off micro inverters is the Envoy metered. It is over complicated for what I want. Way too many options. I want to know what power I am producing day to day, is the net zero functioning correctly, and are the panels being efficient. I want to install the system, get it working, and then more or less forget about it. ( I do realise its not an ideal world!). That's it. All my wife wants to know while i am away is, is it working!
                      Going to do some pricing now and see how the systems compare.
                      Also going to hope that the 'sun tax' charges, that the previous Spanish government introduced, will be cancelled in the near future as promised by the new coalition government. ( I have heard however that politicians lie!).

                      C.R.J.

                      Comment


                      • #12
                        There is no sun tax in Spain for systems under 10kW. You do need to register it though.

                        @C.R.J.: Does your supplier in Germany deliver S type inverters for 50Hz? Note that the S280 is 60Hz only!
                        The S270 Enphase delivers in Australia (Oz), 230V/50Hz, see above, sounds perfect, but, apparently only available there.

                        The only thing that really baffles me is that Enphase has all these nice inverters, beyond S280 there now is IQ6 and IQ6+, but not available in Europe??
                        And they don't reply to customer enquiries. Which quite p*sses me off.

                        I am in touch with a solar supplier who says that the intelligence is in the Envoy, not in the micro-inverters, so if this zero-feed works with the S280 it should too with the M250. Though the tech brief states that they require an S series inverter. (Hello? Enphase? Are you listening?)

                        I really want these micro-inverters because they are supposed to live longer (25 years), and are flexible. With a grid inverter I need to know in advance the sort of power range I want to produce, as there's a minimum and a maximum that they can convert. I'm still pondering what to do about cooking: gas or electric. If we decide it's going to be electric then we'll go for quite a large system. If not, it's going to be about 3kW smaller.

                        And, micro-inverters are suited for diy. They won't go on a roof here, but just on the ground.

                        @C.R.J.: Why does the Envoy put you off? Also with other inverters you will need (external) metering to make sure you don't export power to the grid.
                        To me it sounds as a pretty sleek and straightforward system.. You can access the local device for data, no need to go with Enlighten.

                        rick
                        Last edited by rickj; 07-03-2017, 11:53 AM.

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                        • #13
                          The Envoy-S measures the production watts and consumption watts using C/T''s and it controls the micro-inverters via power-line communications.

                          Enphase Family compatibility matrix
                          https://enphase.com/en-us/products-a...s/envoy/family

                          Envoy-S 50Hz
                          https://enphase.com/en-au/node/44349

                          Enphase Distributors in France, none in Spain
                          https://enphase.com/en-us/global-partner-directory

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                          • #14
                            The Envoy-S measures the production watts and consumption watts using C/T''s and it controls the micro-inverters via power-line communications.

                            Enphase Family compatibility matrix
                            https://enphase.com/en-us/products-a...s/envoy/family


                            Last edited by NEOH; 07-03-2017, 02:31 PM.

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                            • #15
                              Envoy-S 50Hz
                              https://enphase.com/en-au/node/44349

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