FX80 observations

adas
adas Solar Expert Posts: 136 ✭✭✭✭✭
in Advanced Solar Electric Technical Forum #1
Aloha, I recorded the following voltage and amperage:

IN Volts 79V @ 26Amps = 2054W

Out Volts 26 @ 72 Amps = 1872W


Does this mean since the input wattage is 2054 and output wattage is 1872 that the loss in the controller is 2054 * 8.9% loss = 1872?

thanks
frank
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #2
    Re: FX80 observations

    Yes, you are correct--within the accuracy of the equipment measuring the voltage/current...

    Just playing games here, but assuming that there is some slop in accuracy and displayed digits--lets just assume that the Out/In voltage and current reading were a few tenths of a volt/amp the other direction:

    IN Volts 78.6V @ 25.6Amps = 2,012 W
    Out Volts 26.4v @ 72.4 Amps = 1,911 W

    Out/In=95% efficiency...

    Well withing the margin of error of the digits you supplied (assuming 1 volt / 1 amp accuracy).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #3
    Re: FX80 observations

    Frank,

    The calculated efficiency (~91%) looks low. The FM80’s published efficiency spec for an 83 V array at 2,000 W in is a bit over 95% (manual page 61).

    As Bill suggests, higher resolution data values would be helpful. Also note that the FM80 meters are not lab grade devices, and they’re intended to provide a general indication of operational state. I believe the array input current value is calculated rather than measured (I need to verify this), and the controller’s battery voltmeter may need to be calibrated.

    As an example of the above, I once used my old MX60’s display to calculate its indicated low-power efficiency at 88.2%. However, when I used external shunts, I found the efficiency to be 92.2%.

    See: http://www.outbackpower.com/forum/viewtopic.php?f=18&t=952&hilit=shunt

    HTH,
    Jim Goodnight
    “crewzer”
    OutBack Power Systems
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  • adas
    adas Solar Expert Posts: 136 ✭✭✭✭✭
    #4
    Re: FX80 observations

    Aloha, Jim. yes they are not accurate at all. One FX80 says 28.2 and the other says 28.4....both on the same buss. also I told the measurments while the led was in motion and as you know the FX80 moves around much more than the MX60, so by the time I recorded in my mind the incoming voltage and amps, after I shift my eyes to the outgoing to get a mental picture of the reading it already changed.

    ***** so need two people to read symultaneously.

    Frank
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  • boB
    boB Solar Expert Posts: 1,030 ✭✭✭✭
    #5
    Re: FX80 observations
    adas wrote: »
    Aloha, Jim. ....after I shift my eyes to the outgoing to get a mental picture of the reading it already changed.
    ***** so need two people to read symultaneously.
    Frank

    Use a digital camera to take a picture of both displays and then you can get a simultaneous reading .

    boB :D
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