Where is my power going ??

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mtnmankev
mtnmankev Registered Users Posts: 7 ✭
in Advanced Solar Electric Technical Forum #1
I bought a new set of 4 US2200 batteries about six weeks ago, wired for 24 volt system, have new diodes on the positive leads at the solar panels to prevent backfeeding, had my inverter turned off, and the house was plugged into my generator. Battery chargers brought the lights on my morningstar charge controller up to yellow & green, so I decided to let it run a bit longer to bring the batteries up more. When I checked everything a bit later, I found one battery charger indicating full charge but the lights on the controller showed yellow and red. Somewhere, I am losing power. Inverter off and diodes should preclude loss back through the panels or usage from the house. Where am I losing my power?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #2
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    Re: Where is my power going ??

    Not sure were you put the diodes with the solar panels and MorningStar controller--Normally, there is no need for and end users to install blocking diodes as the charge controller prevents battery feeding back to panels at night.

    Any way, can you tell us about the solar array (Vmp/Imp, series and/or parallel array for Vmp-array, number of panels, etc.).

    I guess your batteries are 4x 6 vdc @ 232 AH wired in series for 24 volts?

    And what brand/model/size of AC inverter? How much AC loads do you have? Do you have any DC loads? Have you measured and logged the temperature specific gravity of your cells with a hydrometer?

    I would also suggest you get a DC Current Clamp meter (this AC/DC current clamp DMM is good enough and not too expensive) so you can measure the current in various parts of your system.

    You do want to get control of your batteries--If you take them to "dead" and/or do not get them sufficiently charged (or deficit charging), it can quickly kill the batteries.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
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    Re: Where is my power going ??

    Also be aware that the lights on the Morningstar indicate relative battery VOLTAGE rather than state of charge. DO get yourself a good hydrometer and use that to check your batteries state of charge. Don't be one bit surprised if you find the batteries are badly discharged, as a green light while charging only indicates your batteries are up to a certain voltage, NOT that they are charged! Even worse for the yellow & green you mentioned, far from being charged.
    Do not delay this as I'm sure your batteries are in the process of being ruined because of their discharged condition.
    And YES! GET RID of those diodes between the panels and the charge controller, they're not needed and in fact are reducing the power being delivered by the panels!
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #4
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    Re: Where is my power going ??

    Your charge controller will prevent the panels from discharging your battery bank at night (or any time).

    The idiot lights on charge controllers are less than useless. If you don't know what they mean they can help you ruin batteries.

    Read, and understand, the Battery FAQ's.

    The TS60 comes in 2 versions, one is an MPPT version one is a standard PWM version. Neither is helped by your voltage drop from the added diodes! (I would remove them, which was suggested 3 years ago when you had problems and earlier in this thread) The lights indicate the current system battery voltage. A green light likely just indicates your system voltage is above 25 volts or so, This doesn't tell you much. A system can be at 25 volts while in early stages of bulk charging, or just after sunset with a fully charged battery and a reasonable load.
    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 ✭✭✭
    #5
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    Re: Where is my power going ??

    It has to be asked: you have a 24 Volt system; do you have 24 Volt panels? It sounds like you have one of Morningstar's PWM type controllers. If the panel Vmp is only around 30 the batteries will likely never get charged from them.
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  • mtnmankev
    mtnmankev Registered Users Posts: 7 ✭
    #6
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    Re: Where is my power going ??

    The 4 panels I have are BP solar 24 volt,185 watts each, open circuit voltage is right at40 volts.
    Wired in parallel and heavy wires run the 25 feet to the battery system.

    The panels were used when I got them and had some damage that needed repairing before I could put them in service, which meant bypassing the built in blocking diodes.

    My electrical usage consists of a Direct TV box, a new 17" LCD TV, laptop computer, one LED light (36 LED's) and a small LED clock radio. I can't see where I am drawing a bunch of power. At night, the only thing on is the clock and I am almost out of battery power the next morning, even if I go to bed with a good state of charge in the batteries. I shut down the power strip for laptop and TV so there is no phantom draw when not in use.

    I'm starting to question if my charge controller has gone bad and is directing a power loss somewhere.

    My next step of testing will be to charge the batteries as much as possible during the day, and physically disconnect the controller from the bank at night, and see where I stand the next morning. If I have to, I will install a switch inside the house (with cables running to the controller) so I can make the task easier and not have to go outside and mess with battery terminals.

    When I was in the store in Flagstaff a few weeks ago, I was told the factory blocking diodes in the panels only enter the picture when there is shade, that makes no sense to me but I was pressed for time and didn't stick around to ask for an explanation.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
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    Re: Where is my power going ??

    Okay, terminology issue: blocking diodes aren't bypass diodes.

    It is normal for panels to have bypass diodes, which are in parallel with cell segments. These allow current generated by cell segments to bypass another segment which may be shaded and producing no power. Bypass diodes have no effect on normal panel operation.

    It is not normal for panels to have blocking diodes, which are in series with the whole panel and prevent reverse current flow through the panel when it is not illuminated. Blocking diodes inevitable cut down some of the Voltage the panel can supply. Usually they are Schottky types to reduce the amount of Voltage the drop.

    A panel with a Voc of 40 would probably have a Vmp around 32. Under most conditions this would work directly for a 24 Volt system. Hot operation and/or long wire runs could spoil it. I think the Voc may be wrong, however, as my 175 Watt panels have a Vmp of 35 and Voc around 44. You may have some bad cells in the panels (the need for repair is not a hopeful sign).

    Things to check:

    Actual power usage against battery capacity. I know those batteries; I use them and they are good. You should have plenty of power available from them: around 2.5 kW hours AC.

    Panel power output against actual power usage. If you use more than the panels can put out in a day you will have chronic deficit charging and your batteries are doomed. You have four 185 Watt panels. They ought to make between 5 and 6 Amps apiece or 20-24 Amps total. This should be sufficient for recharging these batteries. Power output (or "harvest") would be at best about 1.9 kW hours. As long as that exceeds usage you should have no problem.

    If the power usage is below the "harvest" and battery capacity you have to check for unexpected power drain. The charge controller may be at fault. First check to see what the SOC of the batteries is in the morning, and how it improves after charging all day.

    The idiot lights are idiotic; you need proper metering to see what is actually coming from the panels and going to the batteries.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #8
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    Re: Where is my power going ??
    mtnmankev wrote: »
    The 4 panels I have are BP solar 24 volt,185 watts each, open circuit voltage is right at40 volts.
    Wired in parallel and heavy wires run the 25 feet to the battery system.

    This may also be an issue... You really need "rated" Vmp~35+ volts minimum to properly/quickly recharge a 24 volt battery bank. On hot summer days, your Vmp~32 volts may have reduced current output.

    Plus, if you have problem panels, they may not all be outputting 100% of their available power. Do you have details on input current (you should see >~80% of rated current on clear sunny days near noon time--if the battery charger is pulling full current.

    And that DC Current Clamp Meter can be quickly clipped on one panel wire at a time--You can see if they are all producing about the same current, or if one or more are producing less.
    The panels were used when I got them and had some damage that needed repairing before I could put them in service, which meant bypassing the built in blocking diodes.

    As Marc said--these are "bypass" diodes and you cannot "bypass" them. You either remove them (clip them out--Not a good idea, panels can be damaged) or you replace the old diodes with new diodes.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #9
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    Re: Where is my power going ??
    BB. wrote: »
    ...these are "bypass" diodes and you cannot "bypass" them. You either remove them (clip them out--Not a good idea, panels can be damaged) or you replace the old diodes with new diodes.

    Other than shading issues, the diodes will have zero effect on any discharging. the Charge controller will not allow for discharge through the panels.

    Many simple things, double check that the panels are connected correctly. If you don't have a clamp meter, you could watch the battery voltage, with a simple meter, as it comes into the inverter. It would be interesting to watch, so you can see what stage the charge controller is in. In the morning the voltage should slowly rise from 24v or where ever it starts to around 28.5volts, this would be the 'bulk' charging, after a couple hours at @28.5volts(absorption stage)(I think the default for most Morningstar) it should fall to around 27 volts, this would be the Float stage...

    If your not around during the day measure the voltage while there is still sun falling strongly on the panels if you get home by 5-5:30 and you have minimal or no loads. It would be good to know if your getting out of Bulk...

    Your VOC panel rating has minor importance in charging your batteries, the number we would like to know is the VMP - Voltage Maximum Power usually about 80% of the VOC.

    If your panels are truly 32 Volts VMP with a little wire loss and some voltage loss through the charge controller, and some due to hot days... you might never be able to properly charge the batteries, and certainly never be able to equalize them properly.
    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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  • mtnmankev
    mtnmankev Registered Users Posts: 7 ✭
    #10
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    Re: Where is my power going ??

    Okay, I finally was able to find and afford a clamp on DC ammeter.

    Here are the results from my 4 panels:

    #1) 24v 0A

    #2) 0v 0A

    #3) 36v 0A

    #4) 24v 4.3A

    No wonder I don't get much power or a decent charge from them ..........

    Guess I will remove the panels and mount 4 of my 12 volt 60 watt panels, and wire them in series/parallel to keep my 24 volt system. Better than no charge.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #11
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    Re: Where is my power going ??

    only 1 panel is working?
     
    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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  • mtnmankev
    mtnmankev Registered Users Posts: 7 ✭
    #12
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    Re: Where is my power going ??
    westbranch wrote: »
    only 1 panel is working?


    Yes, and at a reduced voltage and half the rated watts.
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