help me with this

ron17571ron17571 Registered Users Posts: 19 ✭✭
So help me understand this,if i have either a solar panel or a wind gen. they can put out much juice to the batterys,but because the controller keeps the charge from over charging it would only help if you were charging a large battery setup if you have much amperage?trying to get much bang for the buck i was thinking of a small wind gen.,to help especially at other words people keep talking about putting out mega amounts of power but this is only good if you have the batterys to store it.and a mppt controller lets the charge be more than say the usual 14 volts if needed.mabe i answered my own question.


  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: help me with this

    Just to be clear:

    A solar panel will put out power as long as it is in the sun. What happens to that power depends on a number of things.(OFF GRID) First, is it can be used directly by a load,, such as a light bulb, or a pump or a radio. Second, it can charge a battery,, preferably through a controller. Third, it can send power to a diversion load, such as a space or water heater to bleed off excess capacity. (especially important for a wind genny, as the genny cannot be shut off per sey) The controller will control the voltage and the amperage to prevent damaging a battery with over charging. An mppt controller is just a more efficient way of controlling the charge.

    A well designed, balanced, PV solar system will keep a rough balance between loads, panel capacity and battery capacity.

  • BB.BB. Super Moderators, Administrators Posts: 32,092 admin
    Re: help me with this

    Charge controllers all have the same basic function... To control voltage/current to the battery to 1) charge it, 2) keep it charged without damage, and 3) to allow current to be drawn from the battery to supply other loads.

    You can place several charge controllers together on one battery bank--PV, generator, AC, wind, etc... They will all, roughly, make their own independent decisions on when the battery is charged (they will not coordinate charge states unless there is a digital communications link between controllers of the same brand).

    MPPT, PWM, etc. all do roughly the same thing. PWM tends to be cheaper and used on smaller systems no-a-days.

    MPPT just is a more efficient "Switch Mode Power Supply" that can better match a variable source (solar panels, wind turbines, etc.) and maximize power via the equation Pmaxpv=Vmp*Imp -- and do the same thing on the battery side Pmaxbatt=Vbatt*Ibat.

    MPPT controllers tend to be more expensive and have somewhat higher losses with smaller solar arrays--so they tend to be used on bigger systems.

    There are issues with wind turbines... The standard PV controller works by simply taking less current from the solar panel as the battery reaches full charge.

    A Wind Turbine (horizontal axis wind turbine--HAWT) usually cannot use this type of charge controller... The wind turbine will overspeed if there is too much wind--so the charge controllers are configured to "dump" the excess power from the battery into a resistance heater... Therefore the wind turbine speed is better kept under control.

    There are other ways of controlling wind turbine speed--but the dump controller is usually a standard part of the setup.

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