Can panels actually get better?

solar_dave
solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
in Grid Tie and Grid Interactive Systems #1
So it is only mid March, today temps are cool here in the low 60's, we got some nice clean rain yesterday, my panels are hitting the max output on my inverters at 11AM today. Granted the conditions are pretty ideal today, panel temps are right at 70F.

I have never seen this before, could the panels actually be improving in output? The output is actually about 10% above what PVwatts predicts.
· Share on Twitter

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,639 admin
    #2
    Re: Can panels actually get better?

    No--However, cool weather with very clear skies--and even skies with some light haze have made my system produce more.

    I have seen different models/revisions of GT inverters produce more/less power... The later Xantrex GT series seems to produce better than the 5-7 year old versions (unless they just say they perform better--Solar Guppy said the original GT inverters had accurate logging--presume the newer versions still do too).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #3
    Re: Can panels actually get better?
    solar_dave wrote: »
    I have never seen this before, could the panels actually be improving in output? The output is actually about 10% above what PVwatts predicts.
    PVWatts is actually a bit pessimistic if you use the default derating.
    · Share on Twitter
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #4
    Re: Can panels actually get better?

    I just waded through the hourly data and saw an hour @ 10200 watts when derated to 0.81. So I guess it is not far off.
    · Share on Twitter
  • Juram
    Juram Solar Expert Posts: 36 ✭
    #5
    Re: Can panels actually get better?
    ggunn wrote: »
    PVWatts is actually a bit pessimistic if you use the default derating.



    This. PV Watts generally underrates production by 10-15% if not sometimes more.
    · Share on Twitter
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #6
    Re: Can panels actually get better?
    Juram wrote: »
    This. PV Watts generally underrates production by 10-15% if not sometimes more.
    Of course, by putzing around with the derate factor you can make PVWatts say just about anything.
    · Share on Twitter
  • phred01
    phred01 Solar Expert Posts: 35 ✭
    #7
    Re: Can panels actually get better?

    Solar panels (mono's otr poly's) o/p are rated @ 25 degC. As a rule o/p falls off approx 0.5% per deg increase of cell temperature. Below 25 degC o/p increases by this figure. If the panels are are on tilt frames with a cool wind blowing The cell temperature could drop below ambient
    · Share on Twitter
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #8
    Re: Can panels actually get better?
    phred01 wrote: »
    Solar panels (mono's otr poly's) o/p are rated @ 25 degC. As a rule o/p falls off approx 0.5% per deg increase of cell temperature. Below 25 degC o/p increases by this figure. If the panels are are on tilt frames with a cool wind blowing The cell temperature could drop below ambient

    I suspect this is exactly what is happening. Sun angle optimal in relation to mounting angle, temps cool, like today system peaked at 10,200 watts, previously it peaked the inverter max at 10,400.
    · Share on Twitter
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #9
    Re: Can panels actually get better?
    phred01 wrote: »
    If the panels are are on tilt frames with a cool wind blowing The cell temperature could drop below ambient
    That doesn't make sense to me, unless you've got some sort of evaporative cooling going on
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
    · Share on Twitter

Categories