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Buying A grade solar cells

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  • #16
    Everbright is where I ordered my cells from. (off ebay). I ordered 80, received 88 and only had 1 cracked cell. All others put out the correct power as indicated.

    Hope that helps.

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    • #17
      Grade A cells put out over 95% of theoretical rated voltage under "Solar Test Lamp" light testing (not actual sunlight). They also Produce over 90% of theoretical Rated Open Circuit and Loaded Circuit current under the same "Rated Test Lamp" Testing.
      ...
      How do they determine theoretical rating? By the surface area, cell Wafer composition and manufacturing quality. A given square of any given photovaic cell material has a given electrical property. The only variable is the ability to laser etch the conductive channels (a production process, and one that every cell production plant holds under lock and key).
      ..
      Yes Grade A cells do not exhibit a lot of Micro Cracking/Fractures. This is tested under a microscope. But micro cracking in itself is a natural flaw in ingot production. The presence of micro cracks is not a reason for downgrading a cells quality to "B" instead of "A". But a certain amount of overall micro cracking in the wafer (determined by the manufacturing or receiving plant's Quality Control Standards - which vary some what from one company to the next) could result in a batch of cells being down graded to "B".
      ...
      No! They do not test each and every cell, they do random sampling. Yes, it is conceivable that you could get some "A" Type cells in a few batches of "B" Grade cells - but not too likely. Look at it this way. A Silicon Ingot is sliced (like you would slice balogna or Ham) on a slicer. So if there is a twig embedded in the balogna - then all the slices that were done the length of the twig would have the same flaw (a twig...). So the slices before the imperfection could be "A" Grade and the slices after the imperfection could also be "A" Grade. But the slices containing the imperfection would all be "B" or even "C" Grade. Given the fact that they get hundreds of slices off any one ingot - it stands to reason that they only do in depth testing analysis on so many out of so many total slices. This results is a predictable analysis of the over all batch of wafer slices.
      ...
      Yes - Grade A cells are scarfed up by the Solar Cell Fabricators. Yes - Surplus cells are generally "B" Grade Cells, some have even resorted to selling "C" Grade cells on eBay. "B" Grade cells once encapsulated have a high degree of reliability as compared to "A" Grade cells. Their weakness is in stresses encountered prior to encapsulation. "C" Grade cells are extremely fragile and tend to break under the stress of soldering and laminating. "C" Grade cells will also most likely fail under daily thermal shock encountered in their intended operational environment. So panels built with "C" Grade cells would probably not last 10-25 years, but would most likely fail withing the first 1-3 years.
      ...
      The largest quality variation in PV cells is between the "B" Grade and "C"Grade cells.
      But if you are experimenting and practicing - "C" Grade cells "are a whole lot less of an expense. Why waste good cells in practice.
      ...
      Dave
      dataman19

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      • #18
        Grade A solar cells can be bought from the manufacturers, however MOQ's apply. They won't easily sell a couple of hundred pieces, unless it's a sample order..

        As Grade B solar cells are supposed to have similar power output as Grade A, but visually deviate, the only way to distinguish is to identify their visual defects.

        Need photo examples of different grade solar cells? Find here a complete overview of Solar Cell Grading (A, B, C, D Grade solar cells) with Photo examples:

        Cheers,

        Peter

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        • #19
          Originally posted by rollandelliott View Post
          look up user mlsun
          Got mine from that seller and was very pleased.
          The cells measured exactly what was quoted or better.

          Originally posted by rollandelliott View Post
          it's not that economical
          This is also true, similarly rated ready-made panels work out cheaper.
          Dem

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          • #20
            Don't overlook ARC Coating with crap cells!

            Also don't forget that when a manufacturer does the flash test, and find that the cells do not meet the GRADE A status, NO ARC Anti-Reflective-Coating IS APPLIED!

            Lack of an ARC coating because the cells are not grade-a is a major problem from losing effectiveness at off-angles of sunlight.

            I can also go into business calling my loose cells any grade I want, and to my knowledge, there is no regulation or oversight to be accurate! Talk about caveat emptor.

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            • #21
              Originally posted by PeterGr View Post
              Grade A solar cells can be bought from the manufacturers, however MOQ's apply. They won't easily sell a couple of hundred pieces, unless it's a sample order..

              As Grade B solar cells are supposed to have similar power output as Grade A, but visually deviate, the only way to distinguish is to identify their visual defects.

              Need photo examples of different grade solar cells? Find here a complete overview of Solar Cell Grading (A, B, C, D Grade solar cells) with Photo examples:

              Cheers,

              Peter
              Ban this Chi-Com idiot. Geez digging up a 4 year old thread.
              MSEE, PE

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              • #22
                Originally posted by Sunking View Post
                Ban this Chi-Com idiot. Geez digging up a 4 year old thread.
                Since the linked site appears to be non-commercial, I think I will just warn everyone that any information there should be taken with a grain of salt, as they would for any internet site that they do not know the history and reliability of. Even information on this forum will vary in quality depending on the poster.

                I agree that piggybacking onto a dead thread is not polite behavior.
                But please refrain from personal name calling attacks on members. Attack the post, not the poster.
                SunnyBoy 3000 US, 18 BP Solar 175B panels.

                Comment


                • #23
                  Old Threads

                  Originally posted by Sunking View Post
                  Ban this Chi-Com idiot. Geez digging up a 4 year old thread.
                  Ya know.......I could never understand this knocking of old threads.

                  I mean.....has the knowledge revealed by reading the thread become passe' or something.

                  Does the fact that knowledge was posted a long time ago somehow make that knowledge invalid or wrong?

                  I for one learned a lot from this thread.

                  Perhaps it makes a lot more sense to keep threads going instead of starting new threads every few months or so and repeating the same knowledge in multiple threads.

                  And fwiw, I came here through Google..........and by gosh this thread is good enough for Google......no matter how old it is......and if it's good enough for Google......well then it's good enough for me.

                  Maybe we should kill all the old people while we're at it........I mean.....they're OLD......and what could they possibly contribute?

                  And finally........commenting on how old a thread is seems to me to be trollish behaviour at best........and if that was the intent.....well....ya got me......lol

                  PS. That link is still valid and provides a perfectly good explanation on the grading of cells.
                  z

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                  • #24
                    Now I have a question on broken cells.

                    How do solar cells work anyway........my assumption is that as long as there are trace bars on the piece that are spanning the broken piece, then that piece will still generate voltage and current. Is that correct?

                    And if you had 2 broken pieces that when hooked in parallel would provide the same amperage...or close enough..to an unbroken cell.........well, could you put it in the line and not have any degrading of overall performance of the panel?

                    I'm thinking of making a panel out of broken cells.......so the question of having room on the board for a 2 piece 'cell' would be irrelevant.

                    Also......let's say you had a whole cell and you broke it into 2.....or a crack separated it into 2 pieces....as long as the traces were still intact....would that cell still operate as before? .....or would it depend on which direction and position the crack occurred?

                    z

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                    • #25
                      cells go through an annealing process after they are diced to size. Any cells that crack after that process, will develop microcracks throughout, and will cease to function well.

                      If you are making knickacks and garden art, it's fine, and they will last a few years, but if you want panels to power your house and fridge, buy factory made panels and sleep easy.
                      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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                      • #26
                        Originally posted by Mike90250 View Post
                        cells go through an annealing process after they are diced to size. Any cells that crack after that process, will develop microcracks throughout, and will cease to function well.

                        Thank you.

                        If you are making knickacks and garden art, it's fine, and they will last a few years, but if you want panels to power your house and fridge, buy factory made panels and sleep easy.
                        So let's say a cell cracks in half. Then on both pieces micro cracks will develop along where the cell cracked. Is that what you are saying? What if the cell was encapsulated in a high quality solar epoxy liquid.

                        z

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                        • #27
                          Originally posted by Zardiw View Post
                          So let's say a cell cracks in half. Then on both pieces micro cracks will develop along where the cell cracked. Is that what you are saying? What if the cell was encapsulated in a high quality solar epoxy liquid.

                          z
                          Once a cell has cracked it is no longer anywhere close to being a grade A. It has now become "scrap".

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                          • #28
                            I bought 'A' grade cells from that seller, they all tested the same (up to spec). The panel they made is still working well, but I think the Sylgard 184 has a lot to do with that...
                            Dem

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                            • #29
                              Total joke - as has been mentioned before, there are no solar police to ensure that "grade a" cells, are in fact grade-A before shipment. Actually there are - manufacturers get the true grade-a cells that pass the test - you don't.

                              I have some loose defective cells from 1978. I think I'll put them online, and call them "Grade AAAA++++".

                              There are many unseen manufacturing defects, such as micro-cracks, and quite often the ARC-coating that normally goes on cells that pass the test is not applied to those that don't, before they are passed on to unsuspecting DIY'ers.

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                              • #30
                                If you look hard enough and put in the right "key" search words, you can find just about anything on the web. You will have to buy in bulk though. Try this website or maybe this one....

                                I went to google and this was my search = "solar cells for sale direct bulk grade"
                                Last edited by solar pete; 12-07-2015, 11:31 PM. Reason: no alibarber or aliexpress links please

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