curveture of cells

[pmitch1400]

has anyone got an answer as how to prevent solar cell curveture whilst soldering on tab wires, the cells i am useing have three tab wires . i have tried putting light weights on the cells while soldering and also on a cool surface all to no avail . any ideas out there would be much appreciated


thanks

[Mike90250]

it's differential thermal expansion. Try small dabs of solder, as little heat as possible.......

[pmitch1400]

cell curveture

it's differential thermal expansion. Try small dabs of solder, as little heat as possible.......

does the tab wire not have to be soldered all the way accross the cell, i understood that you had to heat the tab wire the full laegth of the cell.

thanks Mike for the response to my post

[Mike90250]

Well, there is the issue of making contact to the cell over a large enough area, that you have low resistance. Factorys use IR reflow with controlled heat up and cool down, to limit the distortion, with a hand iron, you have to split the difference, use low temp solder, and hope for the best.
2 or 3 soldered dots on the cell, may be enough to handle the power, and not so much to curve the cell. keep the tab wire taut, so no wrinkles develop to crack the cells.

[pmitch1400]

curveture of cells

Well, there is the issue of making contact to the cell over a large enough area, that you have low resistance. Factorys use IR reflow with controlled heat up and cool down, to limit the distortion, with a hand iron, you have to split the difference, use low temp solder, and hope for the best.
2 or 3 soldered dots on the cell, may be enough to handle the power, and not so much to curve the cell. keep the tab wire taut, so no wrinkles develop to crack the cells.

thanks Mike i will try that with my next batch of cells as i have used all that i have right now , i will be getting more when i am in AZ for winter and will start assembling in the spring when we come home again.


thanks