Now You Can Integrate SMA Devices With Modbus

This post was originally published in 2015. The tips and techniques explained may be outdated.

by Christiane Keim (guest post), , 29 Comments
Modbus

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.

 

29 Comments
  1. Gerhard says:

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

    Reply
  2. Bruno says:

    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?

    Thanks.

    Reply
    • Sarah Römsch says:

      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,
      Sarah

      Reply
    • Leonie Blume
      Leonie Blume says:

      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,
      Leonie

      Reply
  3. Edward says:

    Hi,
    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
  4. Alessandro says:

    Hello,
    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.
    Thanks,
    Ale

    Reply
    • Annika Linke
      Annika Linke says:

      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: http://files.sma.de/dl/2585/WEBBOX-MODBUS-TB-US-en-19.pdf
      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
  5. David Calvo says:

    Hi,

    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
  6. Gustave de Kok says:

    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
    • Viktoria Mai
      Viktoria Mai says:

      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,
      Viktoria

      Reply
      • Daniel says:

        Hi,

        Could you please provide the modbus register for the SMA Energy Meter.

        Thanks,

        Daniel

      • Jennifer Rößler
        Jennifer Rößler says:

        Hello Daniel,

        the SMA Energy Meter is not using Modbus protocol.
        Please have a look at our Homepage in the developer section. Scroll down to “Counter Protocol Interface”.

        There you can order information directly from our development.

        Kind regards, Jennifer

  7. Take Aanstoot says:

    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
  8. Michael says:

    Hello,
    Please clarify whether Modbus TCP communication with the Sunny Tripower requires an additional Modbus Interface component or if the Modbus interface is embedded and all that is required is to connect the Tripower to a LAN via Ethernet. Also, is there Wi-Fi support for the STP 30000?

    Reply
  9. Cedric Saveuse says:

    Thanks for posting this.
    The Modbus protocol seems quite difficult for an average user although it is widely supported, even by open source home automation systems. I have a Sunny Boy 5.0, Sunny Island 8.0 and Home Manager 2.0 power plant due to come on line in Indonesia soon. I’m looking at integrating this with Home Assistant in order to automate appliances use based on production times.
    Is there any planned solution to expose sensors via LAN with an easy interface, like a REST API? Are residential end users stuck with using Modbus, an industrial-grade protocol, or go through a cloud hosted solution like Sunny Portal?

    Reply
    • Anna Homberger
      Anna Homberger says:

      Dear Cedric,

      SMA provides the possibility to access our devices locally via Modbus. SMA opted for Modbus because it’s an established industry standard that is highly accepted in the market. Modbus information can be requested via Modbus TCP via LAN. Sensor information can also be requested provided that the device includes this information (e.g. Core1 with sensor module).

      SMA does not currently provide a public API interface in Sunny Portal for remote access.

      If you are looking for a local energy management solution, SMA already offers one such solution.
      Until this segment becomes more standardized, you can now use the full functionality of the existing SEMP (Simple Energy Management Protocol) protocol interface in Sunny Home Manager.

      Additional information on third-party interfaces is available on the SMA developer site:
      https://www.sma.de/en/products/sma-developer.html

      Sunny regards,
      Anna

      Reply
    • Carolyn Schlosser
      Carolyn Schlosser says:

      Hello Bob,

      The Modbus protocol does not include network management, like the extra SNMP does.
      It is made for data transfer between Inverters, dataloggers and customer software (SCADA-Systems).
      The Modbus protocol is available in different SMA devices. Every device has an own Modbus manual.
      Here you can find many information about Modbus:
      https://www.sma.de/en/products/sma-developer.html

      Sunny regards,
      Carolyn

      Reply
  10. Mon says:

    Hello,

    I have a Sunny Mini Central 10000 TL and a Sunny Island 6.0H v11 in my system monitored with RS485 modules with SMA Data 1.

    If I get the Speedwire module for the Sunny Island can i control it via Modbus TCP?

    Does one module replace the other one? How can i control my SMC then?

    Thankyou

    Reply
  11. Hugo says:

    Hello,

    Is it possible to communicate with STP 20000 TLEE-10 by rs485 without using webbox? Using Modbus RTU?

    Reply
    • Carolyn Schlosser
      Carolyn Schlosser says:

      Hello Hugo,

      Modbus RTU is not available in the inverter directly.
      You can change the communication module to Speedwire and use Modbus TCP for your device.

      Please ask your installer for the right module.

      Sunny regards,
      Carolyn

      Reply

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