Low wind, solar combination

ArashiArashi Registered Users Posts: 12
Hey guys, nice forum here. I just added a small wind generator to my existing 100 watt solar set up.


Today the sun is shining, and the wind is blowing at about 10mph. In this wind, the generator only puts out about 10v which isn't enough to start charging a 12v battery.

I however, have the wind charger controller and the solar charge controller attached in parallel to the battery bank. (both charge controllers have blocking diodes)

Here's where dumb question starts....

So if my solar is putting out enough volts to charge the battery (16v), will I still be getting a little bit of charging power from the wind generator also being it's only putting out 10volts? ...because it's all connected parallel to the same charging current that's hitting the battery? (hard to explain) :(

Thanks!

lowwind.jpg

Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,179 admin
    Re: Low wind, solar combination

    First, if both are standard (good quality) charge controllers--you should not need separate/external blocking diodes--they just cause a voltage drop which wastes power and (usually) makes the charging voltage to the battery about 0.5-1.0 volts too low (controller thinks it is charging the battery at 14.2 volts, but is really charging the battery at 13.2 volts--much slower and lower final state of charge).

    And, the second answer--no, the wind charger needs to meet (or exceed) the battery voltage to "put energy" into the battery...

    Double check the wind turbine specs. and make sure that yours meets the wind vs voltage and/or wind vs output power graph (for a 12 volt battery bank). Many times, a small wind turbine will need 12 MPH or higher wind speed to produce any "useful" amount of power.

    Basically, low wind speeds have very little energy content--and small turbines have difficulty in turning that into useful energy.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ArashiArashi Registered Users Posts: 12
    Re: Low wind, solar combination
    BB. wrote: »

    And, the second answer--no, the wind charger needs to meet (or exceed) the battery voltage to "put energy" into the battery...

    Many times, a small wind turbine will need 12 MPH or higher wind speed to produce any "useful" amount of power.


    -Bill


    Doh!! :cry:

    That's what I figured... I was just hoping that I could get some use out of the generator with low wind. Guess I have to wait for some wind!


    Thanks Bill!
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Low wind, solar combination

    Bill's got it right,, the wind genny needs to exceed the battery voltage to give you any benefit at all. That is one of the potential problems with small scale wind. By the time the genny begins to put out useable current,, if it is connected to a PV system as well,, the battery voltage might be ~13-14 volts. By that time the wind genny might be approaching it's cut out speed.

    Also to the neophyte, 10 mph of steady wind seems like a lot,,, it isn't.

    Tony
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