Solar Cell response curve question

[e=mc²]

Does anybody know if the response curve of a Silicon Solar cell, such as the one RatShack is currently offering, is linear. I wish to make either an integrating amplifier or a linear amplifier so that I can calibrate it for Lumens/Candlepower. I have tons of op amps at my disposal, many quad 741's and am looking for a way to convert the current generated by the solar cell into a meaningful value from which Lumens/Candlepower can be derived.
Any tips or suggestions would be greatly appreciated.

Thanks,

e-

 

[Doug S]

For a given wavelength of incident radiation, the output curve is quite linear with the amount of incident radiation provided that you have a low enough impedence load that the cell voltage doesn't rise above about 200mV. The main problem with this type of cell is that its sensitivity curve w.r.t. wavelength is very different from the human eye and thus it is not measuring "light". In fact, these cells are usually most sensitive to wavelengths that the eye cannot even detect.

 

[MrAl]

Hello e,

I'd probably start with a nice op amp like
an OP07. Set the gain for something like
100 or so, short the solar cell with maybe
a 1 ohm resistor, and take it from there.

There's also the possiblity of placing the
cell right across the input terminals of
the op amp, if you have a lower output cell.
You could then figure the gain based on the
current. Im not sure if you can get a cell
with a rating that low or not, might have to
use a photodetector diode.

If you want to use a 741, you will probably have
to employ the offset adjustment pot.

In any case, to get good results you would
most likely have to calibrate it with a known
light meter, as the output from cells varies
quite a bit with their efficiency.

Good luck with it,
Al