SMA will it ever work?

SpikeSpike Posts: 2Registered Users
Hi, I am having a dreadful experience with SMA and after nearly a year I am frankly considering returning the lot, claiming it is not fit for purpose and suing for my money back. I really don't want the hassle of this so am asking for any input you guys can give me. Application is off grid in rural Spain with the need for five hours a day of bore hole pump for irrigation. I'm using a Sunny Boy PV inverter, 3KW of panels, 290 AH Rolls AGM batteries at 48 V and a Sunny Island 6H. From day one I could not get a generator to work for more than a couple of minutes. SMA blamed the generator and its control. I tried five generators, all failed to connect. Finally SMA switched out the Sunny Island and the replacement worked with the generators no problem. Now I have two issues. The first is that state of charge never rises above 80% even though State of health is 100%. The Sunny Island seems to ignore charging current drop as a parameter to end charging instead using just time and also ignores the end of a full charge as an indication of a full battery. Without an accurate SOC I am worried about the long term health of my batteries. Secondly the AC coupling between the Sunny Boy and the Sunny Island is frequency controlled. When I turn off a load like the pump the Sunny Island bangs the frequency up with a time constant of about half a second. The Sunny Boy simply cannot respond that fast and so the frequncy hits the cut off point, the Sunny Boy switches off and then tries to connect again with the same result. I can fix this by adding a 800 W dummy load but should I really have to do this? The batteries draw 400 w or so at the state of charge this normally happens at with another 400 w going to the house. Any insight very welcome, thanks

Comments

  • westbranchwestbranch Posts: 5,084Solar Expert ✭✭✭✭
    Spike said:The first is that state of charge never rises above 80% even though State of health is 100%

    If this is for your AGMs how does the Sunny system  determine these 2 values? Is there an algorithm you can access?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SpikeSpike Posts: 2Registered Users
    Hi and thanks for the reply. For State of Charge and State of Health these are algorithms not explained and not accessible. The only programable parameter I am aware of which impacts is a C10 value. For battery charging there is float cell voltage, boost cell voltage full charge cell voltage and equalise cell voltage. The only charge cycle the user can initiate is an equalise so I have set all the equalise parameters to be identical to a boost charge. Boost charge has absorption time set to 2 hours and full charge to 3 hours. Boost charge initiated by SOC falling below 70%. Every other battery charger I have used terminates absorption on current falling to a low level and I cannot understand why the Sunny Island doesn't do this, it has shunts inside it, it knows what the current is.
  • westbranchwestbranch Posts: 5,084Solar Expert ✭✭✭✭
    What use does Rolls state for those AGMs?
    Mine are Telco purposed and I have extended the End Amps to 1 % of C-20 to max out the charge time as they were designed for Float service and it seems to work for these brutes.  Also set Absorb to the max setting for the winter as it is - 25C these days, drop it back in the summer though.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • inetdoginetdog Posts: 3,121Solar Expert ✭✭✭✭
    edited January 2017 #5
    For the system to have any chance of stability the normal running AC output of the SI must be higher than the amount of load that is suddenly shed (assuming for the moment that there is no generator involved.)
    Otherwise the SB output  alone may be greater than the total remaining load.
    The SI cannot drop its output below zero, so something has to cover the period before the SB responds to the frequency shift.
    One solution is to run your pumps off VFDs (Variable Frequency Drives) and program the VHDs to ramp the pump speed down slowly at turn off instead of just shutting the load off instantly. FWIW this kind of ramped shutdown of the pumps will also be gentler on the pipes.
    As a side benefit you will not have to supply a surge/startup load when turning a pump on. And as a further benefit, if it is one for you, you can run the pumps at reduced speed to save power if you want to operate over a longer time span.

    Use one technology to keep the operation within the parameters that another technology requires.
    SMA SB 3000, old BP panels.
  • WillbWillb Posts: 4Registered Users
    Hi, I'm running a similar setup. I'm 100% sure that your sunnboy is not set to "off grid" mode. The sunny island attempts to throttle the sunnyboy by gradually increasing the grid frequency to a maximum of 52 hz. When in off grid mode the sunny boy would respond to anything between 51 and 52 hz by gradually reducing its output in response attempting to balance the system at 51hz. But as it's not set to off grid mode, It doesn't respond, the sunny island keeps pushing the frequency up until it hits 52, then the SB disconnects completely. That explains why you never get above 80% SOC. The last 20% requites less power, tapering down to a few amps, so the SI tries to regulate the SB which doesn't respond until it shuts down completely.

    If your sunnboy is the TL series it might be Bluetooth. You can connect a laptop and use the small "sunny explorer” software to set off grid mode.

    Will
  • WillbWillb Posts: 4Registered Users
    Also, it's possible that your gen sync issues were caused by narrow margins in the gen connection parameters, although I find them to be very wide be default. You can specify the range of voltage and frequency that the gen is allowed to connect.
  • SurfpathSurfpath Posts: 357Solar Expert ✭✭✭
    You said: The first is that state of charge never rises above 80% even though State of health is 100%
    I agree.  It stinks. My neighbors who use SMA also have the same issue.  SMA seems to use a charging profile that rarely brings Battery SOC up to 100% each day even if the sun is blazing.  Their belief is that 80% SOC is fine with the rare foray up to 95-100%.

    I admit that there seems to be disagreement about the perfect FLA battery charging profile.  But I think most FLA battery manufacturers would encourage off gridders to shoot for 100% daily.

    SMA seems to be hardy and well engineered Kit, but their manuals are frustrating (perhaps the translation from German?), and they don't seem to be as well suited for off-gid application.  My 2 cents.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
  • BB.BB. Posts: 27,698Super Moderators admin
    I am not sure that bringing batteries to >>90% every day is a good thing. And SMA (I thought--And possibly the Midnite Classic) had a setting that had the State of Charge fall below 80% or so before a "full charging" cycle would be initiated--Basically deeper cycling of the battery bank between "full charges" for better battery life (lots of gassing of lead acid will form oxygen on the positive plate, causing lead oxide and corrosion of the battery plate grid--Which you can see on some failing batteries where the positive terminal is "extruded" up through the battery case).

    There is an alternative flooded cell lead acid battery operation of cycling between 80 to 50% SoC, and recharging >90% once or twice a week. And I think one vendor that suggested once every 4 weeks. As long as the battery is cycling every day, there is the suggestion that they will not sulfate if the cells are actively cycled.

    If the lead acid cells are not cycled--Then you do want to keep the battery fairly well charged to reduce sulfation.

    I am not a battery expert/engineer/chemist by any means--Just things that I have read here over the last few years.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Posts: 7,797Solar Expert ✭✭✭✭
    There have to be ways to adjust the charging profile, to allow for large/small battery banks, and AGM vs Flooded
    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
    gen: http://tinyurl.com/LMR-Lister ,

  • WillbWillb Posts: 4Registered Users
    edited January 2017 #11
    If it is set to off grid mode, perhaps the frequency range at which the sunny boy starts to throttle down it's power output is mismatched to the sunny island. It's a bit hazy but I seem to remember that there was some settings that changed the Hz Vs Power slope.
  • WillbWillb Posts: 4Registered Users
    If all the settings are correct then my guess is the battery bank is a bit small, they recommend minimum of 100 ah per kilowatt of solar. Although you are pretty close. If the batteries are empty and able to soak up the PV does the same thing happen when you switch off the pump? .....I wonder if the sunnyboy would respond quicker if the devices were communicating via serial data instead of relying on fspc.
  • BB.BB. Posts: 27,698Super Moderators admin
    Just a clarification... The recommendation (for lead acid batteries) is 100 AH per 1 kWatt of solar (or inverter/loads) @ 48 volts.

    For 24 volts, it would be 200 AH. And 12 volts would be 400 AH.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rhino 660rhino 660 Posts: 4Registered Users
    Had this hz issue on a job on an island
    The fix was to use the usb adapter in the sunny boy and tighten up the FSPC range(frequency shift power controll)
    I had it start sooner and end sooner. I think i moved it 1 hz each way
    Its a 10 kw array and would not throttle down soon enough so the sunny island would shoot up the hz and trip it off
    Now the sunny boy can hold 23 watts
    Before it was screwing up the lights,security sys and Ac thermostat
    And not charging all the way
    If you want higher SOC
    Raise the vpc. A little and lower the cycltmful
    From 14 days to 7.
    None of this i would recommend. Just letting you know how to get it to 95-98%
    100% you need to equalize

    Sunny islands are by far the best. They're not for someone that does not know what there doing.
    Find an installer that has put in and opperated 10-20 and you will need not worry.
    Off grid.
     Temporary system while i build house 
    8.5 kw pv, 70kwh's tesla model S batteries, 4548 xantrex 
    2 60A xw cc 1 80A outback cc. 25kw diesel gen 
    Looking at skybox for 20kw ac 18.5kw dc pv when done

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