Re: How can I make a simple solar cell?

There is no easy or safe way to construct a new solar cell. The materials used, silicon in particular, can give off poison fumes when melted.

I recommend "re-engineering" a cheap solar calculator. Open up the calculator and find the solar cell wires. Try to leave as much length of the wires as you can when you cut or un-solder.

With the appropriate amount of light the solar cell will act just like a battery. For more information on how solar cells work try Mad Sci Search using the key word photovoltaic.

I would use a simple circuit peg board (a teacher may be able to provide one of these) and a small flash light bulb. The bottom flat surface of the light bulb is typically used as the positive connection and the ring of metal is the negative. You can reverse this and see what happens -- this is perfectly safe with a light bulb. A regular light bulb will probably be too dim to see because it will have a higher initial resistance that reduces the energy that actually produces light.

A schematic drawing of the light bulb is shown in Figure 1. You then can construct the simple circuit shown in Figure 2.

If you have access to a voltmeter (or better a digitial multi-meter - DMM) you hook it up around the solar cell or the bulb to see how much voltage is generated or used as a function of light on the cell. Light bulbs are inherently non-Ohmic (non-linear) devices. Figure 3 shows the voltmeter hooked up to measure the voltage at the solar cell.

If you are allowed use commerically available merchanise, you might be able to find an electronic science kit that has solar cell and light bulb in it.

Sincerely,

Tom "Solar Salesman" Cull

Figure 1:

        positive end    {x||O   bulb
                           ^
                           |
                           | 
                           negative edge 


                       
Figure 2:


                                          Light Bulb 

         ----- solar cell -----------------{x||O
         |                                    |
         |                                    |
         |                                    |
         |------------------------------------|


Figure 3:

[V] represents the voltmeter.


             ----[V]-------               Light Bulb 
             |            |
         ----| solar cell |----------------{x||O
         |                                    |
         |                                    |
         |                                    |
         |------------------------------------|