mppt controller working in GRID TIE INVERTER

sujalshahsujalshah Registered Users Posts: 5 ✭✭
Hello dear friends

I am new in solar system. Kindly help me to find out the working of MPPT CONTROLLER in GRID TIE INVERTER 

I KNOW HOW MPPT CONTROLLER WORKS IN OFF GRID SOLAR SYSTEM BUT I DO NOT KNOW HOW IT WORKS IN GRID TIE INVERTER.

THANKS IN ADVANCE

REGARDS
SUJAL SHAH

Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,068 admin
    Are you trying to understand from an Engineering Design or as an installer/end user point of view?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • sujalshahsujalshah Registered Users Posts: 5 ✭✭
    BB. said:
    Are you trying to understand from an Engineering Design or as an installer/end user point of view?

    -Bill
    Dear Bill 

    I am trying to understand MPPT working in off grid and on grid inverter as a installer point of view.
  • mike95490mike95490 Solar Expert Posts: 9,022 ✭✭✭✭✭
    MPPT works by matching the Load to the Panel "impedance", so that the PV provides the maximum power at all times.

    Think of it as "dynamic impedance matching".

    There are several ways to do this, and you can research Manufacturers White Papers on the different algorithms that can be used,

    https://www.victronenergy.com/blog/2014/07/21/which-solar-charge-controller-pwm-or-mppt/
    http://www.morningstarcorp.com/white-papers/
    http://www.ti.com/analog/docs/analogtechdoc_hh.tsp?viewType=mostuseful&rootFamilyId=64&familyId=2120&docCategoryId=9




    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 ,

  • BB.BB. Super Moderators, Administrators Posts: 31,068 admin
    From the installer's point of view--The MPPT circuit does two things... One it allows the solar panel's output power to be maximized for (mostly) temperature of the solar cell. Hot cells will have their Vmp temperature drop (typically by ~20% less than Standard Rating name plate ratings on panel). If you had a PWM (pulse wave modulated, or "on/off" type solar charge controller), you will get less than optimum energy from the panel (Pmax-power=Vmax-power * Imax-power). In theory, for average conditions (not-freezing weather), you can get about zero to 10% more power from a MPPT type circuit.

    The second reason for MPPT circuitry--Most will allow you to run the solar array Vmp-array at a much higher voltage. The MPPT charge controller is (typically) a buck mode switching power supply. This allows the high input voltage/low input current from the solar array to be efficiently down converted (~95%) to the lower voltage/higher current needed to charge the battery bank (or run the AC inverter for a Grid Tied Inverter).

    More or less, this is very similar to what is done with AC circuits. Using an AC transformer to "match" high voltage/low current from an AC distribution circuit  to the low voltage/high current used inside the home.

    The MPPT circuitry/computer "tracks" the optimum Vmp and Imp of the solar panel by adjusting the down conversion ratio (again, like a variable AC transformer or "variac").

    In the end, pretty much every Grid Tied system has MPPT as part of its design (and why you can have 200 VDC to 600 VDC input and connect it to a 120/208/230/240/etc. VAC utility power panel.

    For off grid solar, MPPT circuitry adds cost (and some "extra losses") to a solar charge controller (for equivalent higher end controllers, ~$100-$200 for PWM vs ~$600 for MPPT).

    Smaller Off Grid solar charge controllers, perhaps 400 Watts or smaller, tend to be cheaper with PWM controllers and "standard" 36 cell/Vmp~18 volt panels (cheap charge controllers and more expensive solar panels);.

    For larger systems, around 800 Watts or larger, more expensive MPPT controller plus cheaper GT designed solar panels (60 or 72 cell panels) with Vmp~30-36 volts tend to be more cost effective (expensive MPPT controller + cheap GT panels).

    Also for physically larger systems, and systems with longer wire runs from solar array to charge controller/battery bank, you can run higher Vmp-array (typically for high end MPPT cotrollers) of Vmp-array~100 volts, or with a view MPPT controllers, as high as 200-400+ VDC... This can same lots of money for copper wiring (much smaller diameter copper cable) and/or allow a solar array to be mounted in an open field while the home/cabin maybe shaded by trees.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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