Sunny Boy parameter change eases grid tied battery backup process

Good news to off-grid installers: SMA is happy to announce that starting this month, all approved Sunny Boy inverters will be shipped with the Backup Mode parameter installed to the “On_all” setting.

In a grid tied battery backup application, the relationship between a Sunny Boy and a Sunny Island is like nothing else. Each inverter is in tune with the other and responds precisely when the other makes a request. However, advanced communication protocol is only available when a specific parameter is set within the Sunny Boy.

Previously, the default Backup Mode parameter had been set to “off.” Changing this setting at the factory will simplify installations since installers will not need a communication device to change the parameter setting when installing and commissioning AC coupled systems. One less concern for installers and one more step closer to commissioning and making clean, renewable power.

How it works
A Sunny Boy configured to receive commands from its "master" Sunny Island. Photo: USA Solar.

A Sunny Boy configured to receive commands from its “master” Sunny Island. Photo: USA Solar.

In a battery backup AC coupled application, the Sunny Island will increase its bus frequency to reduce the output power of the Sunny Boy. The Sunny Island performs this frequency shift to prevent the excess PV from overcharging batteries and only increases the frequency when these three conditions exist:

  1. The grid is out
  2. All batteries are fully charged
  3. There is no demand on the protected loads panel

When the Backup Mode parameter is set to “On_All,” the Sunny Boy will respond to the Sunny Island command to enter into “backup mode” when the grid goes down. Once in Backup Mode, the Sunny Boy will open various voltage and frequency windows that are wider than the limits which the inverter is normally constrained to. However, with the Sunny Island as the gatekeeper to the grid, no PV will back feed when the grid is down—the Sunny Boy can operate in this UL approved mode all it wants!

Communication is the key

It’s important to note that the Sunny Boy will only open these windows when the Sunny Island gives the command and it will return to the original default values when the Sunny Island sends a command to go back to the original values once grid is operational. These commands are sent via RS485 wiring that must be installed with the system.

The communication abilities between the Sunny Island and Sunny Boy via RS485 are crucial to the system’s success. Without it, the Sunny Boy would not be able to switch to Backup Mode when the Sunny Island sent its commands. Since the Sunny Boy wouldn’t open its voltage and frequency windows it’s still restricted to the preset frequency limits of 59.3 to 60.5Hz. When the Sunny Island increases its frequency the Sunny Boy will trip off just like a regular grid tied scenario with a bad grid. This same reaction would occur in a system using a non-SMA inverter in an AC coupled application.

To view a list of approved SMA inverters that can ship with Backup Mode enabled, click here.

  1. Noah
    Noah says:

    Hi, I have a Sunny Boy 10000TLUS-12 (circa 2015) coupled to 10.35 kWp of PV in Rhode Island USA. Is the Secure Power Supply retrofittable to this inverter? Is SPS a separate inverter than my existing Sunny Boy or is it an output of my existing Sunny Boy? If it’s a retrofit what is changed on the SB?

    Where can I get pricing for SPS, Sunny Island, and any other options available for emergency backup power in my area?


  2. Nosiru
    Nosiru says:

    Please, My inverter is written F605, and F710. Which the support group instructions is to Run QCG. Please what is QCG and how can I run it so that I can reset my system.


  3. Pasha
    Pasha says:

    System Configuration:
    – Sunny Boy 7.7-US
    – Sunny Boy 3.8-US
    – Pair of SUNNY ISLAND 6048-US-10 inverters
    – Grid-tied installation with 3 BMZ batteries.
    – Located in California, US.

    I am looking for a solution to avoid frequency shift as the control mechanism between SunnyIsland and SunnyBoys, since it impacts frequency-sensitive electronics at the customer residence during grid-fault operation. Is it possible to disable frequency-shift control and have it done over RS485?

  4. jm
    jm says:

    Hello Mike,

    i am having an issue with my sunny island, on the remote screen, it says “no valid grid” and its displays frequency is 50.2 Hz and voltage is 40.7 volts, but the grid feed on the AC2 port is 220 volts!!
    Please help

  5. Veena Vijayan
    Veena Vijayan says:

    I have a Sunny boy 5000tl and a Sunny island 8.0h
    I have 5kw PV modules
    I want to configure my sunny boy as a grid tie inverter alone feeding into the grid. I want my sunny island to charge from the grid alone. Is it possible to configure my inverters in this combination.please help

  6. Ari
    Ari says:

    I have a customer with a PV-Powered inverter (3.5kw), a SB6000 and a SI5048.

    While in off-grid (or back-up mode), sometimes the SI will lower the frequency below 59.3 hz to 58.9 hz. I can guess it is to let the SB to produce as much as it can.

    The issue is that this produces a fault on the PV-Powered Inverter. Therefore, even in low light situations (overcast and mornig/evenings) the PVPowered production is lost when most needed.

    Is there a parameter to limit the low frequency on the Sunny Island?

  7. Blind Zelupoa
    Blind Zelupoa says:

    I am using a SMA Sunny Island 5048 and am facing two issue with my system:

    1. system always shut down on over temperature
    2. display screen on inverter shows 100% SOC at all time (day and night) even with the load on (load connected)

    Please advise. Thank you.

  8. Bj
    Bj says:

    Question about when the grid is up.
    Does the SI pull the power from the battery bank to the loads when the grid is up? Or does the SI take the power from the SB and give it directly to the loads, charges the batteries if needed and then sends excess power back to the grid?
    The reason I ask is my battery grid tie back up system has a cycle (when the grid is up), where the battery bank slowly drains from 95% down to the 70% then goes into boost charging. This cycle consistently repeats every 18 hrs. Please advise. Thank you.

  9. Fabian
    Fabian says:

    Hello. Good day. I have looked at the specs of Sunny inverter series and they are great. I want to install a PV grid tied system with battery backup. What are the complete set of equipment I need to get. I am designing for 10kw PV.

  10. Sven Lindström
    Sven Lindström says:

    “To view a list of approved SMA inverters that can ship with Backup Mode enabled, click here.”

    The link under “here” above did not work? Which inverters from SMA will work in a completely off-grid system with Sunny Island?

  11. Taku MUnemo
    Taku MUnemo says:

    I need to configure a Sunny Boy 4000TL and 5000TL for Botswana. Would you kindly guide me through the step by step process. I do have my SMA Grid Guard Code.

    Please help on the changes I need to make before commissioning.

  12. Lynne Bannen
    Lynne Bannen says:

    Hi Justin,

    I am installing 2 Sunny Islands adding to my current system of 2500 watts w/2500 Sunnyboy on L1 and 2000 watts w/2500 Sunnyboy on L2 on load panel in splt series. Just want to make sure I am reading manual right. For my battery bank I just need to hook up the DC battery to the Master? It is unclear if you need to run positive to Master and Negative to slave. From my take the master runs it all, right? It has been 9 years since I have installed a system so want to make sure I have it right. With the old Sunnyboys they need to each be on the load panel and will come on line when grid goes down, right? I am in USA, Indiana

  13. ganjar
    ganjar says:

    hi, i have one question

    for your information , I am using the Inverter SMA Sunny Island 5048 , and I had to change some parameters to get the setting that suits my purposes

    the problem is, now I want to restore my custom settings back to the default/ factory setting , how do I do that?


  14. azi
    azi says:

    Hi, I’ve a question, may you answer it as a professional in inverters.
    I’m looking for a grid tied inverter with this option: if there is no longer grid for the moment, we can activate Islanding feature and use the output for local purposes in grid pv farm?! Can you help me, if there is a something in the market for this reason? I appreciate.

  15. Joseph Savage
    Joseph Savage says:

    Ok. Understand the ATS concept but doubt locals would accept non UL 1741, then again they might not get it, but anyway my integrity would not allow it.

    Thank you for your time.


  16. Joseph Savage
    Joseph Savage says:

    Correction to previous email. I must have had my thinking cap on sideways, both systems would have to be non Multi cluster.

    The only solution I visualized would be two separate systems, a stand alone non Multi cluster SB set of inverters to back feed the utility and a smaller non Multi cluster SB SI system for backup.

    The maximum size of backup system as non Multi cluster I could build would be 18,000 watts SI as a 120/208 3 phase backup and still be able to back feed as Grid Tie.

    I was thinking of larger backup with the ability to back feed Grid Tie to recoup system cost.

    JD Savage

  17. Joseph Savage
    Joseph Savage says:

    Good Day

    Can you clarify a point for me. I have been thinking about a SB SI MULTI CLUSTER system in Florida but in reading the SI operation manual I found section 16.10 states that a multi cluster system is not certified for GRID TIE OPERATION, is this correct?

    I assume the issue is possible communication errors between clusters and insuring a non-islanding condition.

    If so the only work around I’ve dreamed up would be two separate systems, a SB Multi Cluster GRID TIE system to backfeed to the utility and a smaller seperate non Multi cluster SB SI system as backup.

    This would not be a very desirable situation.

    Thank you for your time.

    JD Savage

  18. James Vaca
    James Vaca says:

    Having issues with Sunny Island and Sunny Boy shutting down. twice in 12 days. after a 25 mins the Sunny Island display screen shows “to start press enter” then system resets itself. second time the display showed T- Batt high. i assume this means battery temperature. Checked outside of temperature of batteries, between 76 -79 degrees depending on the location in cabinet.

    is there service in Jackson, New Hampshire?

    Sunny Island – Ser. # 125500163 Type – S14248 U
    Sunny Boy – Ser. # 2000084863 SB6000U
    Acme Transformer Cat.# T-3-53545-S Style SR

  19. Gerhard Kotze
    Gerhard Kotze says:

    I need to change the backup mode parameter on my Sunny Boy urgently. I’ve requested a Grid Guard code and have been waiting for weeks, in the mean time my batteries aren’t charging properly. Please help!

  20. Mike Messick
    Mike Messick says:

    Great article. This is exactly what I was looking for !
    What is the design process? Is this something you can assist me with?

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