mppt

System
System Posts: 2,511 admin
in Solar Beginners Corner #1
i f i install grid tie solar do i need mmpt ?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: mppt

    gt inverters have mppt in them already.
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: mppt

    the question is y do i need mppt, isn't the mppt to control the charge to battery
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: mppt
    norml wrote: »
    the question is y do i need mppt, isn't the mppt to control the charge to battery

    Not exactly. It's Maximum Power Point Tracking. Down-converting higher array Voltage to the best output for the system.

    Battery based systems use MPPT charge controllers to optimize battery charging. Grid-tie system use MPPT to get the most power from the panels to feed the grid, so to speak. Typically a battery system will be down-converting a '48 Volt' array to charge a '24 Volt' battery, whereas the grid-tie will be down-converting 200 Volts or more to supply 120 VAC.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #5
    Re: mppt

    Like this example:
    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 ,

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  • System2
    System2 Posts: 6,290 admin
    #6
    Re: mppt

    tx for help

    could u please explain function of grid ppm
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #7
    Re: mppt
    norml wrote: »
    tx for help

    could u please explain function of grid ppm

    I don't know what Grid PPM is. Did you typo?
    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 ,

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  • System2
    System2 Posts: 6,290 admin
    #8
    Re: mppt

    i am sorry mppt
    the question is, y not set up the solar system grid tie for 120 v, like this u dont need to lower the volt, i understand u need regular inverter to change dc to ac like transformer
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,640 admin
    #9
    Re: mppt

    The output of a solar panel is not like a standard 12 volt battery bank... It is actually a current source whose maximum voltage*current=power point moves around based on amount of sun, temperature, etc...

    data sheet for a crystalline silicon panel

    So, the MPPT (Maximum Power Point Tracking) is used for both Grid Tied Inverters (no battery bank) and by MPPT Solar Charge Controllers (when charging a battery bank).

    Both types of devices are working to get the maximum amount of solar power from the solar panels...

    There are older solar charge controllers that are called PWM type (pulse width modulation--basically a simple on/off switch) that just takes the available current from the solar panels out dumps it into a battery bank. Less expensive, simple, and not too bad of efficiency if panel Vmp voltage and battery bank Vbatt-charging are matched correctly. (Vmp~Vbatt-charge+2volts).

    -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 ✭✭✭✭
    #10
    Re: mppt
    norml wrote: »
    the question is y do i need mppt, isn't the mppt to control the charge to battery

    you would want it to get the most out of those expensive pvs even if it's to go to the grid instead of a battery bank. i don't know if there is a gt system that does not use it.
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,485 ✭✭✭✭
    #11
    Re: mppt
    norml wrote: »
    the question is y do i need mppt, isn't the mppt to control the charge to battery

    You normally see MPPT term associated with battery charge controllers only because it is always included on a GT Inverter.

    As previously stated, a PV cell is an illumination based current source that is clamped by inherent diode of cell. As a current source, you get more power the higher you let the voltage get, until the inherent cell diode starts to conduct and shunts out generated current. This inherent diode capped voltage has a negative temperature coefficient so it is lower voltage at higher temps.

    An MPPT adjustment hunts for the maximum possible power point based on V*I product, which is primarily the result of temperature changes of the PV cells, and only slightly because of illumination current and wiring losses. For battery charging the more complex V*I panel output hunt can be simplified to maximizing current delivered into the battery. Beside ambient temp, the panels continuously change temp as result of going in and out of cloud overcasts and wind cooling variability .
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