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Panels and power loss during slight amount of shade

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  • Panels and power loss during slight amount of shade

    I haven't been on here for a couple of years and looking to add a few more panels so I'm wanting to know what to look for. I've been using 3 45 watt sets I bought at Harbor freight about 15 years ago. They still work perfectly well and they only lose partial output when a power line throws a shadow across the panels. Two years ago I bought 4 100w panels from HQST. They put out fine also but lose approximately 50% output with the same line shadowing them. These are monocrystalline and I believe the origional panels are also. Two questions, what do I look for to match the performance of my origional panels and also what causes the newer panels to lose so much output?

  • #2
    panels loose output from shade lines, depending on how the cells are wired/oriented.

    And go buy yourself a lottery ticket, old HF panels still working = lucky man
    Powerfab top of pole PV mount (2) | 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

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    • #3
      That was my assumption being the way the panels are wired internally and lucky maybe or possibly these old panels were just a good quality. They were expensive, even purchased on sale I paid 390.00 plus tax for a 135w total combing 9 15w panels. At the time we had power outtage issues often and being self employed I needed to be able to run a few lights, drill, grinder ect. while the power was out. Now that much of the surrounding farm land has what looks like million dollar homes everywhere we rarely have grid failure but still do ocassionally. What do I look for when I search for well performing panels? I could easily go to 24v but would have to replace my inverters.

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      • #4
        Maybe I should rephrase my Question. I do understand that all panels will loose a certain amount of output when a small amount of shade crosses them but what do I look for to get the least amount of loss in a panel before I purchase more panels?

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        • #5
          Originally posted by kg993 View Post
          Maybe I should rephrase my Question. I do understand that all panels will loose a certain amount of output when a small amount of shade crosses them but what do I look for to get the least amount of loss in a panel before I purchase more panels?
          icy cold, bright, windy winter days

          IMHO, only NASA engineers need to worry if a panel fades 1% or 1.2% from heat. The difference might matter for a mountain top radio repeater.
          Powerfab top of pole PV mount (2) | 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

          Comment


          • #6
            As Mike wrote, panels are separated into subpanels and wired together with bypass diodes. For best shade output, you want a panel that is separated into as many subpanels as possible. Common panels are divided into 3 subpanels. Half-cut panels are divided into 6 subpanels. I think that's where terms like "duo" in the model name come from. Another tipoff that a panel is half-cut is that the junction box is centered on the panel, rather than on one end. A large panel supplier like AltE or Renvu will be able to tell you which of their panels are half-cut.
            7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

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            • #7
              Thank you very much bob-n, I knew there was a reason for the my issue. Now I know what to look for and believe or not you really brightened my day this morning. I asked the same question on here 2 years ago and no one could help.
              And I've known all along about heat and power loss. Several years ago I bought some panels and pulling them out of the boxes I saw the black border trim and just put them back in the boxes thinking how ignorant can a manufacturer be.

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