Question ! Please Help.

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System
System Posts: 2,511 admin
in General Solar Power Topics #1
I have

1.) ten 100w 24v 4.16A solar panels
2.) 24v 45A charge controller
3.) 100aH 24V battery x 3
4.) 2000W modified wave inverter

how should i connect the panels to the charge controller ? and then to the battery and then to the inverter ( the safest way ) it would suppose to be in parallel , but wouldn't that get a bit messy ?

how long can my inverter run for at half load if all 3 batteries are fully charged ?

and how long would it take for the ten 100W 24V panels to charge all 3 batteries ?

we are new in this business and we would consider any input.

Thanks.!

horizon star
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  • System2
    System2 Posts: 6,290 admin
    #2
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    Re: Question ! Please Help.

    First a question: What make and model of controller?

    Second, with 3 fully charged batteries, you could provide perhaps 300 AH, but that would kill them stone dead and ruin them. So, since they should never be discharged below 50%, that leaves you with about 150 AH to work with.

    Third, your inverter on half load, considering inefficiencies, would draw perhaps 50 Amps, which would give you 3 hours run time.

    Fourth, especially this time of year, with short days, you may well need 2 days of full sun to recharge the batteries, assuming no energy was taken from the batteries during that time.

    This is a rough estimate, using the limited information provided and my own personal experience and understanding.
    Others will surely provide more precise answers once you can provide more details on things like batteries, expected loads, average hours of sun each day, any shading as well as the direction and angle of panel installation.
    Good luck and remember what I consider a top rule- - It's far cheaper and more efficient to conserve a watt than to generate a watt. You've heard the old saying: Location, location, location, well with producing your own power, it's conserve, conserve, conserve. We've been brought up in an extremely wasteful society as far as energy use is concerned, led to believe it's the norm, so many of us have to rethink our way of life.
    All the best
    Wayne
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  • System2
    System2 Posts: 6,290 admin
    #3
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    Re: Question ! Please Help.

    my controller is a chinese made controller - theres no brand. but its pwm and 45A

    i am from hong kong and I am considered putting these in my home.

    i would want to run some small lights and appliances , nothing major, i was thinking about 500-1000W but only for night time
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #4
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    Re: Question ! Please Help.

    1.) ten 100w 24v 4.16A solar panels

    A "24 V" battery bank requires anywhere from ~28 V to ~31 V at 77 F (25 C) for correct charging and, if required, equalization. Accordingly, "24 V" PV modules and a 24 V controller may not be very effective.

    We need to know more about the PV modules. Specifically, what are the following Standard Tect Conditions (STC) values for each module:

    Voc (open circuit voltage)
    Vmp (max power voltage)
    Isc (short circuit current)
    Imp (max power current)

    More later...
    Jim / crewzer
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  • System2
    System2 Posts: 6,290 admin
    #5
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    Re: Question ! Please Help.

    Also, what appliances? When it comes to small scale solar, most appliances are a lot more major than most people realize. CF lights are one thing, appliances often quite another.
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  • System2
    System2 Posts: 6,290 admin
    #6
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    Re: Question ! Please Help.

    Voc = 28.8 v

    Vmp = 24 v

    Isc = 4.57a

    Imp = 4.16a


    I plan to only run a few LED lights ,a fan etc , i do not plan to run nothing major since its only a experimental project.

    what is equalization ?

    I can get my hands on 48v controller , but not 48v panel array. what can i do ?



    crewzer wrote: »
    A "24 V" battery bank requires anywhere from ~28 V to ~31 V at 77 F (25 C) for correct charging and, if required, equalization. Accordingly, "24 V" PV modules and a 24 V controller may not be very effective.

    We need to know more about the PV modules. Specifically, what are the following Standard Tect Conditions (STC) values for each module:

    Voc (open circuit voltage)
    Vmp (max power voltage)
    Isc (short circuit current)
    Imp (max power current)

    More later...
    Jim / crewzer
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #7
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    Re: Question ! Please Help.

    Noticed that your solar panels are rated at Vmp=24 VDC... For a 24 volt battery, you will need panels that generate ~32 volts or a bit more (maximum battery voltage + ~2 volts for controller drop). For a 48 VDC system, you are looking for a 62+ VDC solar array.

    Now, solar panels connect very well in series--so you can take 3 of them and get 72 volts for your MPPT controller.

    There are a lot of details to read about... Lead Acid Batteries require higher charging voltages as they get colder. Solar panel voltages drop with temperature. MPPT controllers have maximum input voltage and maximum current ratings. Also, there is safety--fuses/circuit breakers to prevent a short/failure somewhere causing a fire (batteries can supply amazing amounts of current--much more than your normal AC wall outlet).

    There are different types of batteries out there--but the standard wet cell lead acid storage battery--Equalization is the process where you "slightly overcharge" the battery and cause hydrogen gas to bubble out. This does several things, it makes sure that each series cell in the battery is fully charged and it also helps mix the acid (otherwise, you will have heavy, concentrated acid at the bottom of the battery and light/watery, acid at the top--over time).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
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    Re: Question ! Please Help.

    be sure the 48v controller can handle the vmp and voc of 3 of those pvs in series for you don't want to damage the controller. most 48v controllers i would imagine could handle it, but please be sure.
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