Energy How fast do solar panels degrade?

Discussion in 'Off Grid Living' started by Zimmy, Apr 17, 2018.

  1. Zimmy

    Zimmy Wait, I'm not ready! Site Supporter++

    I have an opportunity to buy some panels that have been in service 9 years in Texas.

    Everything degrades.....but there seems to be a lot of conflicting data out there for me to mine. I've seen 0.8%-10% per year in use. That's a huge range for 9-year-old panels.

    Is there a short and sweet answer? Please share it.
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  2. Altoidfishfins

    Altoidfishfins Monkey+++ Site Supporter+

    Most panels I've seen claim no more than 10% or so reduced output in 25 years. I may have to correct myself later.
  3. Out in the woods

    Out in the woods off-grid in-the-forest beekeeper

    Anyone who says a specific answer is guessing.

    It depends on the techniques used during manufacturing.

    One of my neighbors installed his system in the mid-1980s, his system is still producing roughly 90% of the rated amounts.
  4. ochit

    ochit Monkey+

  5. TnAndy

    TnAndy Senior Member Founding Member

    I think most have a 25 year warranty to still produce 80% at that time. That would seem to indicate less than 1%/yr, assuming it's linear.

    I do know we tested some Arco panels in class I took in 2008. Made by Shell Oil back in the early 80's, and in continuous service since, that looked like crap..faded, looked like something bled over under the glass, etc, and they were putting out over 90% of their rated power.

    But given how cheap panels are now, unless you're getting a steal, I'd buy new.
  6. Zimmy

    Zimmy Wait, I'm not ready! Site Supporter++

    My price point is $1/Watt. I don't know if they will take it or not
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  7. oil pan 4

    oil pan 4 Monkey+++

    You should be able to get new panels from a near by solar installer who buys them by the shipping container for close to $1 per watt.
    That's what I'm going to do. Lubbock and abq solar installers have pretty good deals on them.
    But they're almost always big 200w and up 30ish volt panels, typical of what they use in grid tie solar installs.
  8. T. Riley

    T. Riley Monkey+++ Site Supporter++

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  9. techsar

    techsar Monkey+++

    As long as I do my part keeping them clean, I haven't seen mine drop below rated specs in over five years. Of course they were putting out roughly 105-110% new. So that's less than 0.5 percent per year. Your mileage will vary.
    Before shipping, some of my panels were less than fifty cents per watt...down from two per watt for earlier purchases. If you're close enough to pick them up from the warehouse, savings could be substantial.
    Personally I wouldn't give more than 0.50/watt for used panels...

    Eta: ... I would say stay away from the used ones completely if they are of Chinese origin.
  10. TnAndy

    TnAndy Senior Member Founding Member

    You can buy brand new made in USA Solarworld 285w panels for 75 cents/watt. My best offer on used ones wouldn't even be 50 cents.

    Solar Panels - Prices
  11. Zimmy

    Zimmy Wait, I'm not ready! Site Supporter++

    Thanks. Good info.

    Money is super tight right now but I was gonna find a way when I thought it was a deal. I’m eating my preps now. (perfect time for rotation but spotlights my early preponderance of beans and rice)

    It’s nice to know I have a little room to breathe.
  12. Altoidfishfins

    Altoidfishfins Monkey+++ Site Supporter+

    DM Solar - Solar Panels, Grid Tie Solar Power Systems and Photovoltaic Cells!

    • Solartec 335 Monocrystalline Solar Panel as low as $0.65/w
    • Hyundai 270w Monocrystalline Solar Panel as low as $0.9/w
    • Hyundai 250w Polyocrystalline Solar Panel as low as $0.9/w
    • DM 158w Monocrystalline Solar Panel as low as $0.85/w

    I bought the 158w panels for powering my Travel Trailer about three or four years ago. These particular panels come in sets of two and are monocrystalline. They claim an efficiency of 18%.

    Six of them run my travel trailer, (recharging the batteries and powering the trailer) including the microwave. I use a 1500w inverter on a 24 volt system, which is separate from the TT. It won't run the air conditioner. For as often as that's needed, I can fire up a genset. I may get two more panels.
    Last edited: Apr 17, 2018
  13. Cruisin Sloth

    Cruisin Sloth Special & Slow

    So true , It's HEAT that degrades the crystal , so same panel but different install , one is right on the roof and no air gap underside , while the second same panel is mounted on a tin roof with a 3" air space underside & runs much cooler , that one degrades less.

    % wise I have NO idea

    Them are the panels to acquire ^^^ Get yur head around 12Vdc & move into the 2020 area . Were MPPT and the higher the battery / base voltage system to collect harvested more WATTS !!
    So many run 30ish panels in 3 series to have 120Vdc and then MPPT controller down to 96Vdc bank (like here) or 48Vdc also like here .
    Most solar story's / tales from PRE 2010 are out of date . We have many types of panels & cell structure and amounts .
    I run 72 cell type .

    Ask many questions , but on the correct forums :
    A Forum run by Enthusiasts of MidNite Solar - Index
    OutBack Power Technologies User Forum • Index page
    Northern Arizona Wind & Sun Solar Forum
    MidNite Solar Inc. Renewable Energy System Electrical Components and E-Panels
    Solar Electric Power Systems For On & Off Grid | Panels and More | NAWS
    OutBack Power Inc - Customers

    Here are some links .
    Edit add
    Sign yur name Sloth Dumas
  14. arleigh

    arleigh Goophy monkey

    I started off buying used ARCO panels and still have them working . some of them well over 40 years old . each of my panels is on a switch and to meters for testing .
    Far as I'm concerned, any panel that has a voltage rise above battery voltage is a contributor .
    Something is better than nothing .
    About the only time I replace a weaker panel is if I have something stronger to put in it's place but that does not condemn the panel . It's still handy for putting on the tractor while not in use or other equipment that only needs a bit of a trickle while not being used .
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  15. BenP

    BenP Monkey++ Site Supporter+

    I bought a pallet of new ones on eBay for 50 cents per watt with free shipping.
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  16. techsar

    techsar Monkey+++

    Got some monocrystaline panels many years ago from eBay....never again. Lifespan of about three years before water intrusion caused issues.

    Buy quality once and be done with it!
    Cruisin Sloth likes this.
  17. Cruisin Sloth

    Cruisin Sloth Special & Slow

    well this depends on connection , And if in series , the weaker panel rules the power it can pass .

    Thats the WAY ! I bought a SEACAN 40 foot & filled it with Canada Solar Pallets double stacked ,out of china to Boeing /Paine airsort.
    There I split loaded & the yanks came & got there's or they shipped them to them . 24 units or 12 , 24 was the same shipping cost.
    That is how it is done .

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