mppt controller shutdown

wrongway
wrongway Registered Users Posts: 7 ✭
in Off Grid Solar & Battery Systems #1
Hi Like minded gang,
I have 5 x 200 watt 48 volt 'on grid' panels, running through a 60 amp mppt charger/ controller to 5 x 110 amp/hr 12 volt batteries.I am off the grid. Both panels & batteries are configured in parallel so i have 1000watts / 48 volts delivering to 12 volt / 550 amp hour battery setup..All good so far?
The controller shuts down constantly on hot summer clear days, giving a 'low voltage' alarm. The system works well on cloudy days, now we are getting into Autumn in Tasmania & the sun is a little lower, it's working well in the morning & afternoons mostly. It never fills my batteries, shutting down @ low battery levels is common. I believe the controller / charger settings are sound. I have to use the generator to charge the batteries on hot clear days due to lack of charging. p.s. The Charger is only powered by the panels & not by the batteries so no night time investigations can take place.. I have racked what remains of my brain but can't find a reason for the shut downs, any clues? pps mppt charge controller is 60 amp capacity i've seen 44 amps max produced before shut down. pps, charge controller is 60 amp, i've seen 44 amp produced before shutdown.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: mppt controller shutdown

    welcome to the forum.
    shutting down on hot days sounds almost like the heat is lowering the pv voltages and it's going too low to properly operate the cc at your desired voltage. you may need to give all of your specifics here like pv make and model with at least stating the vmp. what controller are you using? how about the wire size and run length as the voltage drops can be detrimental?
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #3
    Re: mppt controller shutdown

    To charge a 48V battery in summer, you'd need a Vmp rating on the panel of about 72V. What is the exact Vmp rating printed on your panel? I'm inclined to agree with neil that the most likely cause is that the heat is dragging down the voltages down.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: mppt controller shutdown

    Hi "wrongway", welcome to the forum :D
    First thought - - Oh Oh, 5 batteries in parallel - not good for the life of the batteries :cry:, but not likely your immediate problem, just problems to come due to extreme problems keeping those parallel batteries all at the same state of charge.
    Some questions:
    Make and model of your MPPT controller.
    Make and model of your solar panels.
    Is there ANY shading whatever on your panels when your system shuts down?
    Length and diameter (gauge) of those cables.
    Length and gauge of cables between controller and batteries.
    What do you have for batteries, are they "deep cycle marine"?
    How is wiring configured at the batteries to ensure the resistance and wire length/size between each battery and the controller is exactly the same?
    These answers will give us things necessary to consider in trying to come up with possible causes.
    Thanks.
    Wayne
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #5
    Re: mppt controller shutdown

    For wiring of the batteries, you can look at the Smart Gauge website for a good explanation. Improperly wired batteries can cause them not to share current well.

    Regarding:
    The Charger is only powered by the panels & not by the batteries so no night time investigations can take place.

    This does not make sense... The controller should connect both to the solar panels/array on the input side, and the battery bank bus on the controller's output side.

    Solar charge controllers are (almost always) powered by the battery bank and will not work correctly if disconnected from the battery bank (some controllers set their charging voltage 12/24/48 volts based on battery voltage. And if the battery voltage is too low (typically below 10 volts, or "dead", the controllers will not even initialize).

    Are you using a blocking diode between the battery and the solar charge controller or On/Off switch? None of that is needed and can cause problems (see above).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #6
    Re: mppt controller shutdown

    My first thought is you have 'on-grid' panels that are not producing adequate 'off-grid' charge voltage...

    Solution would be making 2 strings of 2 panels in series which would give you adequate charge voltage out of your MPPT charger. You will have 1 panel left over...
    this way at least you will not kill your batteries.
     
    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,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • wrongway
    wrongway Registered Users Posts: 7 ✭
    #7
    Re: mppt controller shutdown

    Thanks so much all for the response...i will gather all those details in the morning & post. It's a 'Stand alone' CC 60 amp, The elctrician who wired it all up said he had the cable size sorted as the distance from panels to cc was minimal, i'll get the other details in the morn. stephendv, it's a 12 volt system. 5 x 110 amp / hr 12 volt batteries in parallel, not 48 volts...that's the panels...i'm a first time forum user so forgive me while i find my legs..Niel...interesting comments...thanks...i have such a small power need, this system should work soundly. It's now 09.00 hrs & the cc is reading 39volts from the panels, multimeter is reading 39.9 volts. The cc is rated 40-120 volts...So i don't have enough volts! I guess the question now is do i replace the cc with a wider ranging one or could i series wire some panels to up the input voltage? Thanks again for all your help.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #8
    Re: mppt controller shutdown

    OK can you give us the make and model of all the hardware you have including the specific data on the back of the panels, so we can sort out just what you have going.
     
    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,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #9
    Re: mppt controller shutdown

    scratch my thoughts on not having enough voltage as i was under the impression you had a 48v battery bank. we still need the particulars to even begin to try to help you.

    but then again you say this, "The cc is rated 40-120 volts.." which i'm confused about the 40v lower point.

    "The elctrician who wired it all up said he had the cable size sorted as the distance from panels to cc was minimal,..........."

    what does this statement mean?
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  • wrongway
    wrongway Registered Users Posts: 7 ✭
    #10
    Re: mppt controller shutdown

    it means the cables were sized correctly...the cc is situated within 2 meters of the panels. i think you are right re the voltage, i think i need to increase the input voltage to the cc. Details - 5x200watt 48volt panels connected in parallel. 1x 60amp, 40-120 volt 'Stand Alone' MPPT cc. 5x 110 amp/hour 12 volt batteries, connected in parallel. i think the lower voltage point of the cc is my problem. You may want to re-scratch!
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  • wrongway
    wrongway Registered Users Posts: 7 ✭
    #11
    Re: mppt controller shutdown

    i'll have to remove a panel to get the details, that will take a few days to sort out. Thankyou!
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  • wrongway
    wrongway Registered Users Posts: 7 ✭
    #12
    Re: mppt controller shutdown

    thankyou! It does make sense 'coz that's what it is. I specifically sought a cc that shut down @ night & didn't draw power from the batteries, no point having a unit that remains on @ night! I'm not using a blocking diode. Thanks again!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
    Re: mppt controller shutdown

    Could you give brand and model on these panels and controller?
    A "48 Volt" panel is a rare thing. Most 200 Watt GT panels would be about 30 Vmp and 6.5 Imp. Almost any panel should supply sufficient Voltage for charging a 12 Volt system. Increasing the array Voltage would not offer any advantage and may make things worse. If the array Voltage is low then something is wrong with the panels or wiring.
    Your 1000 Watts should be able to "max out" a 60 Amp controller on a 12 Volt system. This should be plenty for 550 Amp hours of battery.

    The wiring from array to controller could be carrying 33 Amps @ 30 Volts and ought to be at least 12 AWG for 2 meters.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #14
    Re: mppt controller shutdown

    btw, to my knowledge there aren't many if any pvs that are 48v vmp. we need to know what equipment you have and the specs. aren't there any names stamped on the cc with a model number?

    also, find out what gauge wire the electrician used and how long it was one way. he may have sized it, but it does not mean he did it with low voltage drops in mind as many go by the standards set for utility electric which are at least 10x the voltage making a difference of at least 10x for the v drop.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #15
    Re: mppt controller shutdown
    niel wrote: »
    btw, to my knowledge there aren't many if any pvs that are 48v vmp. we need to know what equipment you have and the specs. aren't there any names stamped on the cc with a model number?

    I'm betting thin film panels, these come in higher voltages...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #16
    Re: mppt controller shutdown
    Photowhit wrote: »
    I'm betting thin film panels, these come in higher voltages...

    Oh joy. Next you'll tell me the controller is a BZ. :p
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #17
    Re: mppt controller shutdown
    Cariboocoot wrote: »
    Oh joy. Next you'll tell me the controller is a BZ. :p

    actually, that's the abbreviated name that they came up with after they kept hearing it go bzzzzzt.:p
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  • wrongway
    wrongway Registered Users Posts: 7 ✭
    #18
    Re: mppt controller shutdown

    thanks to all for your help, the issue has now been sorted. Niel your first instinct was correct, a lack of voltage from the panels caused the continuous shut downs.
    i have dropped one panel & have 2 sets of 2 panels, 2x2 in series then each set connected in parallel increasing the voltage to cc to approx 80 volts. I now need to either get rid of a panel or buy another one!
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #19
    Re: mppt controller shutdown
    wrongway wrote: »
    I now need to either get rid of a panel or buy another one!

    If you can get another, it's usually the best way to go. Most of us add loads over time.
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