Please help!! Sma sunny boy

adam1984
adam1984 Solar Expert Posts: 72 ✭✭✭✭
in General Solar Power Topics #1
So i have a PMA wired in to a Sunny Boy 4000US. The output of the PMA is 440V. This allows optimum performance. Here is the dilemma. Since the SMA inverter has MPP tracking, it keeps trying to change the voltage. However, the PMA runs very rough when it tries to lower the RPMs. It keeps lowering the voltage, and what i want to know is how i can stabilize the voltage at 440V. The PMA doesnt run well at 350Vdc where the inverter is trying to take it. The input can be anywhere from 280-480, but i dont want it shifting the voltage. Any suggestions to stabilize the voltage at 440 and prevent the inverter from MPP tracking? Thanks in advance.
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  • adam1984
    adam1984 Solar Expert Posts: 72 ✭✭✭✭
    #2
    Re: Please help!! Sma sunny boy

    Also, the inverter is functioning great regardless, but the PMA really struggles below 440. However, even changing the RPM's to lower it to around 360 still makes it run roughly, so the preference is to keep the voltage at 440.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
    Re: Please help!! Sma sunny boy

    Can you define what PMA is ? I've understood it to be a Perm Magnet Alternator. They generally have no regulation, and are designed to produce a certain voltage at a specific speed. Change speed and the voltage and frequency changes.

    Maybe give us a bigger view of what's happening.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: Please help!! Sma sunny boy

    I am thinking you need to contact SMA directly and see if you can program the mppt to a specific voltage.

    The only other thing I can think to do is use a transformer (or three) to drop it to around 220 volts or whatever the mppt floor is for your unit. Probably not practical for your system.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • NEOH
    NEOH Solar Expert Posts: 74 ✭✭
    #5
    Re: Please help!! Sma sunny boy

    Did SMA confirm that their Sunny Boy 4000U would work with a wind driven PMA instead of a Solar Panel? Typically, an Inverter will need to be custom programmed to the Power Curve of the PMA. A standard Grid Tie MPPT Solar Inverter will not work well directly connected to a wind driven PMA. Programming the Power Curve is not simple or easy. You definately need to contact SMA for help. Some Inverter companies will not even give you a warranty on the Inverter if you do not use their Inverter + PMA combo. I just read an article re: GINLOG brand having a "good' Inverter and PMA combo.

    Did you consider a WindyBoy instead of a SunnyBoy ???

    Make sure you have proper PMA Over-Voltage protection, too.
    With a small load the Volts will get very high.
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  • adam1984
    adam1984 Solar Expert Posts: 72 ✭✭✭✭
    #6
    Re: Please help!! Sma sunny boy

    Thanks for the post guys. So it looks like i will have to contact SMA. It isnt a wind turbine persay. It needs 120Vac to start rotation, and once it does, it self produces the voltage. I probably should have looked into the windy boy, however the Sunny boy appeared to work since i didnt see the difference between panels and PMA's as they are both DC voltage. I just didnt know if there was a way without programming. Perhaps a device to wire between the PMA and the inverter that would hold or stabilize a certain voltage. It runs perfect at 440, and the SMA operates great at 440, but once it tried to shift voltage to 360 it runs very rough.
    Thanks again guys.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #7
    Re: Please help!! Sma sunny boy
    adam1984 wrote: »
    Thanks for the post guys. So it looks like i will have to contact SMA. It isnt a wind turbine persay. It needs 120Vac to start rotation, and once it does, it self produces the voltage. I probably should have looked into the windy boy, however the Sunny boy appeared to work since i didnt see the difference between panels and PMA's as they are both DC voltage.
    Well, yes, but the SB is going to keep changing the DC load looking for the optimum MPP for what it assumes are solar modules driving the DC bus. What is that going to do to your machine and to the inverter? You may have already voided the warranty on the SB by using it for other than what it was designed for.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #8
    Re: Please help!! Sma sunny boy

    You could try setting the Operational Mode to "V-Const" instead of "Mpp-Operation". And then define "Vconst-Setpoint" with the fixed voltage you want to use.

    Pages 11 and 14 here: http://download.sma.de/smaprosa/dateien/1348/SB_SMC_WB_Par-TEN102640.pdf
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  • adam1984
    adam1984 Solar Expert Posts: 72 ✭✭✭✭
    #9
    Re: Please help!! Sma sunny boy

    stephendv: Thank you very much
    So this is what it looks like im going to have to do:
    1- Purchase a webbox and RS-485 card and some cat 5 cable to connect to the inverter.
    2- Apparently through HTTP interface, you are able to program in the Vconst and change the operating mode and set the parameters to change from mpp to vconst, which then allows you to input the voltage. Probably should have used the windy boy, but this is what i have right now.
    3- It isnt good for the device to lower the rpms and drop the voltage. First, it destroyed the belt i had in there. Second, it sounds like a dying goat (or some farm animal) when the rpms are lower.
    Thanks again for all your help. Ill let you know how it turns out.
    Adam
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #10
    Re: Please help!! Sma sunny boy

    Hi Adam,

    The webbox is a rather expensive (cough, overpriced, cough) bit of hardware if all you really want to do is change the parameters.
    Double check with the SMA guys, but I think the simplest way is to use the free Sunny Data Control software installed on a PC: http://www.sma.de/en/products/software/sunny-data-control.html
    Then you can either use the USB service interface to connect to the PC or the RS485 piggyback and corresponding RS485-USB adapter for your PC.

    RS485 is the recommended route if you want a permanent monitoring solution whereas the USB service interface will be easier if you just want to make occasional config changes.
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  • adam1984
    adam1984 Solar Expert Posts: 72 ✭✭✭✭
    #11
    Re: Please help!! Sma sunny boy

    GUYS. THANKS FOR ALL YOUR HELP! So i got it working and changed the value to vconst at 440V. For whatever reason, it was outputting 3kW on MPPT, but now that it is at 440Vconst, it is only producing 11W. Clearly there is an issue. Any suggestions?
    Please see attachment for parameter settings. I believe the issue is somewhere in there.
    Thanks
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  • adam1984
    adam1984 Solar Expert Posts: 72 ✭✭✭✭
    #12
    Re: Please help!! Sma sunny boy

    Also i am changing the parameters via sunny data control, a free service.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #13
    Re: Please help!! Sma sunny boy

    I would just drop the voltage down in ~10% steps and see what happens...

    It is possible that the reported voltage vs the voltage setting is not "the same units"... I.e., you might be reading 440 Volts DC peak, and here you are setting 440 VAC or ~1.4x higher (sqr root of 2 conversion from VDC to VAC sine wave) than VDC...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #14
    Re: Please help!! Sma sunny boy

    Now that Bill has mentioned AC, what exactly is being fed into the SB?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #15
    Re: Please help!! Sma sunny boy

    My guess is rectified DC... Could be single or 3 phase (3 phase being a much smoother wave form).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • adam1984
    adam1984 Solar Expert Posts: 72 ✭✭✭✭
    #16
    Re: Please help!! Sma sunny boy

    It is a PMA being fed into the sunny boy. MPPT mode worked great, and it was cranking. However, the PMA ran very rough when it tried to drop the voltage, so i changed it to a constant voltage, however now it appears there is no output. 3kw MPP, 11W Vconstant. Obviously some issue with the parameters.
    Bill, when you say change the voltage around 10% each, do you mean Vconst or other parameters? The start voltage may also need to be changed, i assume? Thanks.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #17
    Re: Please help!! Sma sunny boy

    Is it single phase or 3 phase? do you have a rectifier between the PMA and sunny boy?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #18
    Re: Please help!! Sma sunny boy

    Purely guessing... Vconst, just drop it by ~10% (x0.9) at a time and see the results.

    From an engineering point of view, typically "scaling" (multiplication/division) parameter changes make more sense than absolute changes (i.e., 10% drop of 400 volts would be 360 volts, and 10% drop of 40 volts is 36 volts--Vs telling you to drop xx volts at a time). More or less a guess that the MPPT internal numbers/external readings may be "constructed" differently than Vconst settings/readings... Moving my 10% at a time, you may stubble on the "optimum" Vconst setting.

    You can play with other settings (Vstart) and such--but I have zero knowledge about these inverters--So take what I say with a grain of salt.

    Asking the vendor how Vconst vs MPPT function readings would probably be a big help--They might even find a programming error.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • NEOH
    NEOH Solar Expert Posts: 74 ✭✭
    #19
    Re: Please help!! Sma sunny boy

    You are trying to use Sunny Boy (ie Solar Controller) in Constant Voltage Mode (ie Fixed Vmp) with a Wind Turbine that wants to have a varying Voltage with varying RPM. Typically, a Windy Boy will have a different optimal Voltage + Current combination for different Wind Speeds. The Windy Boy uses a non-linear function to obtain maximum power from a Wind Turbine. I do not understand how the Fixed Voltage mode of a Sunny Boy can be a good (useable) setting for a Wind Turbine.
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