Enter Zipcode

Results 1 to 6 of 6

Thread: Low Amperage with Solar Cells

  1. #1

    Default Low Amperage with Solar Cells

    Hello,

    I have recently purchased 108 3"X6" solar cells from ebay. I have tabbed the negative (front) side of every cell and made 4 columns of 9 cells in series so far. The voltage always comes out to approximately 0.5V/cell (varying light and temperature) and 0.03A (30mA)/cell.

    The cells are rated as 0.5V and 3.6A , so I am wondering why my amperage has been reduced by a factor of about 100?

    Originally I thought The columns of cells could have a problem with them but then I started testing individual cells and got the same current reading.

    I have emailed the manufacturer and he asked about the quality of my multimeter, but I ahve tried both a fluke and radioshack multimeter to measure the current and there was no deviation in the value. The seller has very high positive feedback and seems legitimate ( fred480v). Does anyone else have any experience with cells from this buyer?

    When I soldered the cells I made sure there was a good connection on all of them through visual inspection and a light tensile test, being careful not to damage the cells, but I did use high heat (570-630F), could this be destroying the cells?

    When I measured the cells, I connected one wire from positive( back) and one from negative( front) to the multimeter. I also took readings with the two front wires connected at a node and the two back as a node because it seems as if this is the way they are wired in the end, but I obtained the same value.

    Is this the right way to measure the current?

    Thank you for your time and assistance.

  2. #2
    Solar Fanatic
    Join Date
    May 2012
    Location
    Placerville, CA. In the Sierra Foothills, around 2000 ft. altitude, occasional snow.
    Posts
    5,034

    Default

    Quote Originally Posted by mikeconnor5353 View Post
    Hello,

    I have recently purchased 108 3"X6" solar cells from ebay. I have tabbed the negative (front) side of every cell and made 4 columns of 9 cells in series so far. The voltage always comes out to approximately 0.5V/cell (varying light and temperature) and 0.03A (30mA)/cell.

    The cells are rated as 0.5V and 3.6A , so I am wondering why my amperage has been reduced by a factor of about 100?

    Originally I thought The columns of cells could have a problem with them but then I started testing individual cells and got the same current reading.
    How much light was hitting the cells during your test? Ideally you should be testing outdoors, in full noon sunlight and with the cells aimed directly at the sun.
    The voltage will be independent of the light, as you noticed, but the current will be directly proportional, and any amount of indoor light will give you a lower current than full sunlight.

    How are you connecting the meter to measure current, and what meter range are you using?
    You can also measure current before tabbing the cells (if you have any left untabbed) to rule out heat as an issue.
    A good practice is to try tabbing on just one cell to confirm that you are not doing obvious damage to it before going on to do the rest as a batch.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

  3. #3

    Default

    When I hook the multimeter up to the panel, I hook the negative lead to one of the tabbing wires on the front or negative side and the positive lead goes to one of the white squares on the back. Should I be contacting both tabbing wires on the front and all white squares on the back when measuring current?

    Also, I have no more cells to test that have not been tabbed, but that is a very good idea. Do you think that 570-630F would damage the cell while saughtering? What temperature ( or if you dont know the temperature, what wattage) do most people use when tabbing cells?

    Thank you for your response

  4. #4
    Solar Fanatic
    Join Date
    Aug 2012
    Location
    Wisconsin, USA
    Posts
    419

    Default

    You should test each cell before stringing them together, because one bad cell will bring down the amps of the whole string. What I do is use a 60 Watt lamp about a foot above the test area and test each cell. You don't get the full rated amperage (far from it actually) but you figure out what number you should be getting, then the bad cells will show up as much lower. With the B Grade EBay cells you WILL have some bad cells, you want to find them and not use them.

  5. #5
    Solar Fanatic
    Join Date
    May 2012
    Location
    Placerville, CA. In the Sierra Foothills, around 2000 ft. altitude, occasional snow.
    Posts
    5,034

    Default

    Quote Originally Posted by mikeconnor5353 View Post
    Do you think that 570-630F would damage the cell while saughtering? What temperature ( or if you dont know the temperature, what wattage) do most people use when tabbing cells?
    So called "low temperature" solders melt at less than 180C, which would be 350F.
    Inexpensive lead-free solders may melt as high as 480F. If you need to go to 630F, you are using the wrong kind of solder and you do risk damaging the cells. But I would not expect all of them to be affected equally.
    The wattage of the iron does not make nearly as much difference as the heat capacity of the tip, since the time of contact should be short (~1 second or less) if you are doing it right.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

  6. #6
    Junior Member
    Join Date
    Jan 2012
    Posts
    4

    Default Fred

    Quote Originally Posted by mikeconnor5353 View Post
    Hello,

    I have recently purchased 108 3"X6" solar cells from ebay. I have tabbed the negative (front) side of every cell and made 4 columns of 9 cells in series so far. The voltage always comes out to approximately 0.5V/cell (varying light and temperature) and 0.03A (30mA)/cell.

    The cells are rated as 0.5V and 3.6A , so I am wondering why my amperage has been reduced by a factor of about 100?

    Originally I thought The columns of cells could have a problem with them but then I started testing individual cells and got the same current reading.

    I have emailed the manufacturer and he asked about the quality of my multimeter, but I ahve tried both a fluke and radioshack multimeter to measure the current and there was no deviation in the value. The seller has very high positive feedback and seems legitimate ( fred480v). Does anyone else have any experience with cells from this buyer?

    When I soldered the cells I made sure there was a good connection on all of them through visual inspection and a light tensile test, being careful not to damage the cells, but I did use high heat (570-630F), could this be destroying the cells?




    When I measured the cells, I connected one wire from positive( back) and one from negative( front) to the multimeter. I also took readings with the two front wires connected at a node and the two back as a node because it seems as if this is the way they are wired in the end, but I obtained the same value.

    Is this the right way to measure the current?
    Thank you for your time and assistance.

    Have traded with Fred along time. I even have multiple packs as you have described. Remember its either higher current or Higher voltage you cant have both..So your array should be reading about 19 Volts+ but your current will remain the exact same as it reads on a single cell. or you can have an array of .5 volts an higher current. Also note if there is a bad cell, the entire array will only show that cells maximum AMP for the entire array. Depending on your mulitmeter getting accurate current reading is somewhat difficult without being under load. How are you going to seal your cells, liquid or EVA. I suggest eva, a hair dryer is what I have used works really well. Took me 2 panels unfortunately to get my desired effect. Attached is my first failure working on my new design.
    Attached Images Attached Images

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •