Maximum PV Array Output

dsp3930
dsp3930 Solar Expert Posts: 66 ✭✭✭✭
in General Solar Power Topics #1
I have three Sharp 224s (ND-224UC1 / +10/-5 percent rating) hooked up to my XW-MPPT-60. Today I was getting 862 watts out of them. Is a 22% increase over manufactrer rated watts normal in the winter? Measurement taken at Noon ET, 24 degrees F, full sun, and 1" of snow on the ground.

Makes me curious ... do any specific panels perform better than others in the cold and/or less sunny parts of the country?

David
· Share on Twitter

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Maximum PV Array Output

    You will see advertising that xyz panel does better in cloudy weather or qwerty does better in hot weather.

    For the most part, it is not really truthful. All silicon crystalline panels have pretty much the same output characteristics and all panels output energy proportional to the amount of sunlight hitting them.

    You can see the temperature effect on current/voltage/power in this generic spec:

    data sheet for a crystalline silicon panel

    I guess that amorphous panels may have less temperature affects--but it is not much and you need ~2x the surface area for amorphous panels vs crystalline panels.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • dlenox
    dlenox Solar Expert Posts: 42 ✭
    #3
    Re: Maximum PV Array Output

    David,

    I have four Mistubishi 180 watt panels and at about the same tod as you I was getting between 900-1000 watts. Located in WV.

    So yes.

    Dan Lenox
    · Share on Twitter
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #4
    Re: Maximum PV Array Output

    David,

    YES ! Think blending of topologies! Close to the chest here but you can figure it out!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

    · Share on Twitter
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #5
    Re: Maximum PV Array Output
    dsp3930 wrote: »
    I have three Sharp 224s (ND-224UC1 / +10/-5 percent rating) hooked up to my XW-MPPT-60. Today I was getting 862 watts out of them. Is a 22% increase over manufactrer rated watts normal in the winter?

    You can blame the magic of the MPPT controller for the extra watts.

    Cold weather ups the output voltage, a PWM just ignores it, MPPT downconverts it. Is it worth the extra money? I think so.
    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 ,

    · Share on Twitter
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #6
    Re: Maximum PV Array Output

    Thank the combination of cold Pv temps, plenty of reflection, plus some significant mppt boost. 22% is pretty good. I get that much boost fairly regularly depending on battery state of charge,

    Tony
    · Share on Twitter
  • Blayd
    Blayd Registered Users Posts: 21 ✭✭✭
    #7
    Re: Maximum PV Array Output

    I got some high readings also the last time I adjusted my PV for optimum solar imput by setting the angle to the highest reading on the MPPT.

    In my case, while the controller gave the appearance of extra output, the reality was that the voltage at the panel leads (determined by my multi-meter) multiplied by the PV amperes on the MPPT controller equaled the maximum rated output. No small feat since dust and micro-abrasion will over time degrade the output of the panel.

    Cold while slighly increase the output, heat will reduce it.

    Here in the desert mountains my system gets slammed with both extremes. 25 to110 degrees F, which isn't ideal for battery banks.:cry: My next project is to climate control the batteries.
    · Share on Twitter
  • dsp3930
    dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    #8
    Re: Maximum PV Array Output

    I may not have a full grasp of how the MPPT controller is working based on responses ...

    The watts I reported were from the input side of the controller. ("PV in Power" and not "DC out Power").
    · Share on Twitter
  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #9
    Re: Maximum PV Array Output

    What you missing to understand is PV panels are very temperature dependent on the power they produce. Panels come with a name plate rating that is at one specific temperature and irraidiance point. Increase or decease these and the power that the panel will produce changes

    If you have a 100 watt panel, its 1000 watt-meter-squared ( how bright the sun is in essence ) and a temperature of 25C ( 77F ). For each degree C colder than 25C, the panels voltage increases ~0.5%. so if your at 24F that's ~-4F. or about 29C lower than what the name plate rating is

    So your energy output could be 25 - -4 = 29 * 0.05 = ~14.5% higher using an Mppt controller.

    Then you have the reflective effect of snow, which makes the average light on the panels more that the 1000 Wms rating. This is pretty linear, but one could easily get 10-20% increase on this at certain times during the day

    It doesn't matter if your looking at the input our output values on the XW-Mppt, it reports Volts, Amps and Watts very accurately ( all other controllers on the market do not have this ability for accurate measured values ) ... the only difference between input and output is that on the input your volts will be higher and amps lower than the output readings. The Mppt converts the higher input voltage into a higher output current
    · Share on Twitter

Categories