Now You Can Integrate SMA Devices With Modbus

From Christiane Keim (guest post) on April 14, 2015 in Category Technology with 17 Comments

SMA is opening its doors to third-party suppliers and will equip inverters with the Modbus protocol interface, starting immediately. SMA Product Manager Falko Schmidt oversaw the introduction of Modbus at SMA.


Modbus_ENFalko, briefly for newcomers: What does Modbus do, and what are its advantages?

Modbus is a simple, commonly used protocol structure with obvious advantages. This industry standard makes it possible to flexibly connect SMA devices to non-SMA systems using TCP (Transmission Control Protocol).


Why did SMA wait until now to offer Modbus?

The Modbus interface is nothing new to SMA. We have been using it for years in our data loggers, such as the Sunny WebBox and the SMA Cluster Controller, as an interface to third-party suppliers. In commercial PV systems, Modbus is currently the solution for such things as connecting to a SCADA (Supervisory Control and Data Acquisition System) operations management, with an SMA data logger serving as a concentrator.


For a PV system operator, what are the advantages of a direct Modbus interface compared to the interface in the SMA data logger?

If it is necessary to implement third-party monitoring, SCADA or data logging systems, Modbus provides a direct and open system interface to the inverter.


Do solutions with Modbus communication replace data loggers, such as the SMA Cluster Controller?

No, when the Cluster Controller is combined with the SMA Speedwire Communication to the SMA inverters, it basically offers a wide range of integrated system, service and interface functions that are ideally geared to market requirements. In addition, there is an option to implement sustainable, innovative system solutions, as it is possible to access the SMA inverter’s entire volume of data. In contrast to direct system communication via Modbus, where the main focus is on system monitoring and easy system management, a system based on SMA Speedwire offers the following advantages: extremely fast reactions to measurement signals thanks to quick data exchange, upgradable system components, systems with regulatory requirements, direct interface to the Portal, with expanded service, monitoring, analysis, alarm and reporting functions and simplified SMA service with regard to the overall system.


Why does SMA need to have a Modbus connection to inverters for third-party suppliers? What about RS485 and SMA Data 1?

Up until now, our RS485 interface with the publicly disclosed SMA Data 1 protocol has served as a connection for third-party suppliers; this connection has been well-established in the market for years and has proven itself again and again. However, market requirements change, and the issue of PV system controllability is becoming ever more prominent.

For example, we need a certain speed in communication in order to activate an emergency shutdown. That is also why we rely on Speedwire (SMA Ethernet) for the SMA Cluster Controller. Ethernet gives us precisely the amount of power we need in the lines leading directly to the inverter. In addition, switching to Modbus TCP reduces system costs for integrators and customers. If they have previously connected their SMA inverters to their preferred system exclusively through RS 485, they can now save the cost of an RS485 interface.


However, there are already suppliers in the market that support SMA Data 2 Plus via Speedwire (SMA Ethernet) in their data loggers. Why is SMA now also offering Modbus and SunSpec?

SMA Data 2 Plus is not publicly disclosed for various reasons. The suppliers that already offer this “compatible” solution have only “re-engineered” the SMA protocol: They interpret the values that are transmitted via Speedwire. This means, in turn, that these manufacturers are also vulnerable to every future change that we make to our products. In addition, there is a danger that SMA inverters could be damaged due to faulty communication and improper handling. SMA cannot and will not accept any liability in regard to our devices for this kind of fault where a protocol is used that does not follow our specifications.


SunSpec has now come up a number of times. What is it?

SunSpec is a standardized, Modbus-based communication protocol of SunSpec Alliance. A data point mapping similar to a translation table, SunSpec is integrated into SMA devices.


What exactly is SunSpec Alliance?

SunSpec Alliance is an association of manufacturers from the photovoltaic industry. As a member of SunSpec Alliance, SMA supports the goal of standardizing data and channels of communication for photovoltaic systems, regardless of the manufacturer. This enables SMA to ensure that we will always be compatible and up to date for our customers.


Why is standardized communication for PV systems so important?

For customers, this means that they can install devices without referring to the manufacturer. They can build their systems without restrictions, regardless of the PV components that have been used. But manufacturers also profit from standardized systems. Products can simply be taken from the warehouse shelf to be integrated into a system solution.


Thanks, Falko, for the interview.


More information on Modbus can be found on our product page.


4.33 avg. rating (88% score) - 3 votes

The Author

Christiane Keim (guest author)

Christiane works at SMA Germany as a copywriter in the Department of Product Communications.


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  • avatar

    Take Aanstoot

    March 11, 2017 at 14:35

    SMA STP9000TL-20

    We manage to get modbus working over the ethernet interface of this product, but not over the extra RS-485 addon we got recommended to speak directly to our SCADA system. How do we activate Modbus-RTU?

    Reply »
  • avatar

    Gustave de Kok

    March 5, 2017 at 03:30

    Bizarre changes have happened. For years I was able to see the current on each string of a TriPower through Webbox TCP Modbus. e.g. 31793 String current, string 1 (A) [A1.Ms.Amp] . After a (forced by SMA support) firmware upgrade, addresses 31793-31803 are not available any more. This is a major problem as I can’t see if anything is wrong on the 54 strings we have in our system.

    As usual, SMA support never replies to emails to solve this. Perhaps you have an answer?

    Reply »
    • avatar

      Viktoria Mai

      March 8, 2017 at 14:27

      Hello Gustave,

      this is a specific problem, which we can not solve here. Please contact our service line (the appropriate number can be found here by selecting a country).

      Kind regards,

      Reply »
  • avatar

    David Calvo

    September 27, 2016 at 12:37


    I am trying to read dat from a sunny sensorbox with a RS485 bus, directly from a third party system, so I need to know the protocol to communicate. I understand it is Modbus-RTU.
    Do you have any example of a data frame (in hex format) I have to send to read a register?

    Thanks in advance.

    Reply »
  • avatar


    September 1, 2016 at 16:19

    I’m interfacing via Modbus/Tcp (read input register) a SunnyWebbox with a few Sunny Tripower 17000TL-10 inverters attached thru your proprietary RS485 bus.
    I can properly read every info (including Energy Total Yield at address 30513) from the Inverters but I can’t read Energy Daily Yield.
    I’ve found many different modbus tables and have tested many addresses (30517, 40210, and so on) but without result.
    At which address is this info located ?
    I understand you have this info available, the sunny webbox webserver shows it when you select the attached inverter.

    Reply »
    • avatar

      Annika Linke

      September 2, 2016 at 11:44

      Hi Ale,
      We regret to tell you that register 30517 is not supported by the STP 17000TL-10. Please follow the link below to be redirected to the current technical descriptions for the Sunny Webbox MODBUS interface:
      In the table for the device family STP nn000TL-10, the measured values and parameters supported by the STP nn000TL-10 device family are listed.
      Kind regards, Annika

      Reply »
  • avatar


    May 11, 2016 at 08:46

    Is it possible to access modbus data from WebConnect / SpeedWire?

    We would like to connect an external outdoor Display Unit to the Inverter to display PV production (Current Performance, Total Production, C02 Reduction).

    The Display Unit support SO/RS485/RS232/LAN interfaces.

    If Web Connect supports modbus, we may be able to use LAN interface.

    Reply »
  • avatar


    March 19, 2016 at 01:12

    Is STP5000TL-20 support modbus RS485 interface by adding RS485 modbule?

    Reply »
    • avatar

      Leonie Blume

      March 21, 2016 at 14:32

      Hey Henry,
      The STP5000TL-20 can be upgraded with a RS485 board. To get modbus data from this device you need a gateway.
      If you still have a Sunny WebBox, this will be possible. Unfortunately the WebBox is discontinued.

      Another possibility is to use the factory installed Speedwire/Webconnect function.
      In this case a gateway is needed, too. The SMA Cluster Controller would be the right choice.

      Best regards,

      Reply »
  • avatar

    Hernalsteen Tim

    November 26, 2015 at 19:00

    Hi Leonie,

    any idea if this can be integrated in a Loxone domotics concept ?



    Reply »
    • avatar

      Julia Stunz

      December 3, 2015 at 15:09

      Hello Tim,
      Unfortunately we are not able to proof 3rd-party software applications for compatibility with our devices.
      Please have a look to our new information page for developers, hopefully you will find additional information for your request:

      Please note that, except for the information contained in the link above, we cannot provide you with any additional technical support in the integration of our products.

      Kind regards,

      Reply »
  • avatar


    September 16, 2015 at 12:07

    This looks like a great feature!

    I’m also interested to find the exaustive list of SMA inverters that are supported (I’m not sure about the excel file you’re talking about in your comments).

    In particular, is the STP10000TL-20 inverter supported?
    If not, is there any chance it will be supported in the near future?


    Reply »
    • avatar

      Sarah Römsch

      September 21, 2015 at 16:10

      Hi Bruno,
      I’m sorry for the late reply.
      Thank you very much. Unfortunately, your inverter doesn’t support Modbus and won’t do it in the future. I’m sorry for that.
      An alterntaive would be the interface RS485.

      Best regards,

      Reply »
  • avatar


    May 8, 2015 at 07:46

    Any idea when this will be available in South Africa and which model inverters will support modbus?

    Reply »
    • avatar

      Leonie Blume

      May 8, 2015 at 09:23

      Hi Gerhard,

      thanks for your question. It doesn’t depend on where you are but which inverters you use.
      Here you find the list of inverters with Modbus:

      Best regards

      Reply »
      • avatar


        May 8, 2015 at 11:33

        Thanks, Leonie

        The datasheet only shows the Sunny Tripower, is that correct?


      • avatar

        Leonie Blume

        May 8, 2015 at 13:06

        Oh, I’m sorry, the link wasn’t clearly indicated. No, I meant the technical information below. It’s an excel file with different tabs for each product.
        Best regards

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