Typical panel degradation?

System
System Posts: 2,511 admin
in General Solar Power Topics #1
Does anybody have any typical numbers for how much power PV panels lose per year? I know it depends on the type of panel and conditions etc. I'm looking for some ballpark numbers for some spreadsheets I am doing on breakeven. Thanks!

P.S. I'm a new member in Texas and doing my first system, a small off-grid system using a few Kyocera 135s.

-Rob
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #2
    Re: Typical panel degradation?

    All Si panels are warranty for 25 years to 80% ... I'm in the group that thinks there is no life limit for Si panels ( the cells themselfs anyways )

    Nothing else on the planet a consumer can buy has warrantys of this many years

    Asi is another story ..
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: Typical panel degradation?

    I agree that a 25 year guarantee is amazing. If the manufacturers guarantee the panels to put out at least 80 percent of the original power, then the average annual degradation would be less than 0.9%. ((1 - 0.09) to the power of 25) is 0.80.

    My question is about what happens in the real world? Do people see a reduction in power like this? I understand that it is hard to isolate this variable. I also understand that 20 years of data does not exist for the latest designs.

    In one scenario, this creates a difference between 19.5 years and 21 years for payback. Maybe I am making this too complicated!

    Thanks.

    -Rob
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
    Re: Typical panel degradation?

    My panel configuration is ~ 15 years old. I have no specific data to answer your question, but anecdotal evidence is that they put put the same amperage now as they ever have, given equal conditions. I recently doubled my capacity, but the amperage numbers remain just double.

    Icarus

    PS. I think you are making it too complicated. In the real world I agree with SG that barring damage from outside source (hail, lightning, fire etc) they should perform long after your gone.
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  • System2
    System2 Posts: 6,290 admin
    #5
    Re: Typical panel degradation?

    Sage, sounds like you're trying to figure out how many years they will run before you have to replace them.
    I'm with Icarus, they'll still be operating fine - - long after we're no longer in need of them.
    Wayne
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  • System2
    System2 Posts: 6,290 admin
    #6
    Re: Typical panel degradation?

    Hi. No, I'm not worried about replacement life. I was playing with a spreadsheet looking at breakeven time. The biggest unknown seems to be the future price of electricity that is being replaced by solar. A quick look says one scenario would have a 30 year breakeven at today's price and a 19.5 year payback if electricity cost increases 4% per year.

    FYI, I looked at some US DOE numbers and found that the 2002-2006 increase for residential electric customers was 5.4% per year, that same period in Texas was 12.4%. http://www.eia.doe.gov/cneaf/electricity/epa/epa_sprdshts.html

    So I got to thinking about the degradation of the solar panels and wondered if it was a significant factor. If you plug in 80% at 25 years then payback goes from 19.5 years to 21 years in my example. But this is based on the minimum guarantee and not actual performance, so it seems to be worst case.

    But if Icarus says that he does not see any degradation in 15 years, then I am inclined to drop this factor from my analysis. As a newbie, I don't mind looking into some things only to find they are not important for first-order calculations. Thanks!

    -Rob
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #7
    Re: Typical panel degradation?

    Wayne,

    When are you planning on being no longer in need? I'd like your panels then if you please!

    Tony
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  • System2
    System2 Posts: 6,290 admin
    #8
    Re: Typical panel degradation?

    Haha, no plans, just facing reality, I'm not here forever, just dust in the wind, or on someones panels. LOL :p
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