0
$\begingroup$

Here on this slide on page 54:

solar cell table

Only the short-circuit current ($J_{SC}$) is given with respect to area, whereas the voltage stands without relation to area. One could calculate it, because the area is given.

I just wondered, since I never heard about a open-circuit voltage density, but a lot about short-circuit current density.

$\endgroup$
  • 3
    $\begingroup$ Could you please spell out the acronyms? $\endgroup$ – mike stone Oct 26 '20 at 18:43
  • $\begingroup$ VOC = Open-circuit voltage JSC = Short-circuit current density ISC = Short-circuit current $\endgroup$ – AskingBecauseIHaveQuestions Oct 26 '20 at 18:46
  • $\begingroup$ Again, I get downvoted for asking a question which should be understandable for everyone with basic knowledge of the field. 1 second on Google would also yield the answer. These are very common abbreviations. Not my fault. :/ $\endgroup$ – AskingBecauseIHaveQuestions Oct 26 '20 at 20:20
  • $\begingroup$ @askingbecauseihavequestions I read "Vereenigde Oostindische Compagnie". Here area few more: en.m.wikipedia.org/wiki/VOC $\endgroup$ – my2cts Oct 26 '20 at 20:29
  • $\begingroup$ Solar cells and so are are part of electrical engineering. This is a basic physics site, so most of us may know about the basics of semiconductor physics, but the language of the electrical enineering is often unfamilar. $\endgroup$ – mike stone Oct 26 '20 at 20:52
1
$\begingroup$

A solar cell generates a current by collecting photons over its surface area. But solar cells come in many different sizes, so to allow them to be compared with each other the current is normalised by the area.

The open circuit voltage is not dependent on the area, but the other properties of the diode. It does have a dependence on illumination intensity. For this reason IV curves are quoted at standardised conditions.

$\endgroup$
  • $\begingroup$ But couldn't you say that a larger solar cell will also be able to store more energy, is a "stronger capacitor" in a way? $\endgroup$ – AskingBecauseIHaveQuestions Oct 27 '20 at 9:54
  • $\begingroup$ Got to be a bit careful with terminology because they don’t store energy, it’s being converted from sunlight and flowing out as current in a finite amount of time. It’s a stretch to call that storing energy. But I get what you mean. A larger cell has more photo generated electrons but the same number of photo generated electrons per unit area as smaller (or even larger) solar cell under the same illumination. $\endgroup$ – boyfarrell Oct 27 '20 at 10:28
  • $\begingroup$ Yeah, the storage would only sustain as long as illumination would sustain and the individual electron-hole pairs (or should I say "excitons"?) recombine anyway really quickly. So, if you say they are the same with respect to unit area, why is there no VOC density (per unit area)? :/ $\endgroup$ – AskingBecauseIHaveQuestions Oct 27 '20 at 10:31
  • $\begingroup$ Think of VOC as a constant of the material being used. In truth it is related to how the device is designed also but that’s not a bad approximation. It’s not a function of area. So has little meaning. You can of course plot it and convince yourself. $\endgroup$ – boyfarrell Oct 27 '20 at 10:40
  • 1
    $\begingroup$ Yes, I often learn by having conversations, so thank you as well! $\endgroup$ – AskingBecauseIHaveQuestions Oct 27 '20 at 16:43

Not the answer you're looking for? Browse other questions tagged or ask your own question.