Impedance Spectra of Dye-Sensitizedd Solar cells

[khaledparvez]

Can anyone tell me how can I take the impedance spectra of a dye-sensitized solar cell ? Do I need to irradiate (i.e. AM 1.5, 100 mW/cm2) the solar cell during impedance measurement? or I can measure the spectra without irradiating light ? More specifically, how can I get the comparison between Open-circuit voltages between two solar cells ??

 

[MATLABdude]

I'm unclear of what you're asking (as may others on this forum). Are you trying to determine the open-circuit voltage under:

• Varying frequency of light used to irradiate the cells?
• Varying intensity of broad-spectra light used to irradiate the cells?

Or are you seeking voltage output under varying load conditions?

EDIT: to get "Open-circuit" voltage as close as possible, just use a measurement device with very high impedance (e.g. a multimeter with 10 megaOhm input impedance). Use something which has much higher impedance (by an order of magnitude or two) than the internal impedance of whatever it is that you're attempting to measure.

 

[khaledparvez]

I'm seeking voltage output under varying load conditions...

 

[MATLABdude]

I understand. Normally, I'd advise you to work out the internal resistance of the solar cell, but this may be tricky as this probably varies based on the ambient light and load (I am not a specialist in photovoltaics).

In this case, assuming you have, say, a lamp or something which will give you near constant irradiance, you can use a decade resistor box and measure the voltage across the connections as you vary the load (I recommend the decade resistor instead of a potentiometer as it can usually dissipate more power and is more precise within decades).

Actually, I'm not sure whether or not they still make decade resistor boxes. A Google search for decade resistor box turns up many hits, so I'd assume that they still do.

EDIT: If those are two rich for your blood, or of insufficient power dissipation, I'd suggest making a guesstimate as to the power output of the panel, and then buying appropriately-sized power resistors (e.g. 10 W, 1 ohm) I doubt that it'd happen, but the worst-case scenario is that one of your resistors would start on fire (but only if it's grossly undersized: e.g. 1/4 W resistor dissipating 5 W--so do it on something that won't start on fire!)

Also, if you're at a university, ask around; someone's bound to have one (especially if you have a Physics or EE department)