PV Gap

Kathleen Said:

Can i make a solar cell from many small signal diodes like in this picture?

We Answered:

Yes.

Those are the same diodes I told you that you could use in your previous question.

Arlene Said:

Whats the difference between Solar cell and a photo diode?

We Answered:

The photodiode is like a switch: light it up and electricity can flow through it. But that electricity is supplied externally.
A solar cell, using essentially the same photo-electric principle, is intended to generate electricity.

So, one is used as a sensor. The other as an energy producer. Different application.

Greg Said:

I am trying to make a solar cell from small signal diodes...?

We Answered:

0.04v is 40 mV first of all.

Voltmeters read voltage, not current.

When you have only one lead of the meter connected, the meter is picking up random signals from the air, such as RF or 60 Hz energy. Touching it with your finger increases that pick up of signals from the air as you body is now acting as an antenna. These readings are meaningless. You can get that by just letting the leads dangle.

A diode with no voltage applied is a very high impedance, so it will pick up noise from the air, just like the leads do, or your finger does. Put a resistor (10k perhaps) across the diode. This will shunt out most of the noise, and you will see if you get any voltage from the diode acting as a solar cell.

Shine a bright light on it and turn if off and on and see if the voltage changes.

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