Laser Powering a Solar Cell Experiment

How much current does a simple over the counter five dollar laser produce when hitting a small solar panel?  I wasn’t sure, so I did a little experiment.

Using my handy multimeter, I determined the laser circuit was 4.5V at 25 mA.  Since W = V * A, 4.5V x 25mA is 112.5mW.  Now that’s just the internal circuit power.  There’s a sticker on the the cheap-o laser explaining the laser output is < 5mW.

I had a small photovoltaic sensor from All Electronics, that has an output of about 0.5 volts.  When placed under a lamp it produced 2mA of current.

When the laser was directed on the sensor, the current registered 4.5mA.  This means 0.5V x 4.5mA is 2.25mW.

The reading includes the background lamp light, so the power generated by the laser hitting the cell is much less.  A lot of the light was lost due to reflection, but my objective wasn’t to test the light output of the laser.  I really wanted to see how much power could be generated on the solar cell side.