Make a Solar Panel Using Diodes!

So, solar panels are made of silicon...diodes are made of silicon.  Have you ever wondered if diodes conduct current induced by light?  Sure you have, and so have I, so let's experiment and make a solar panel using 1N4148 (run-of-the-mill) diodes.   This is just a brief instructable, as the full construction is left up to you, intrepid reader, as a fun project. 

Check out the video below to see how much voltage you can get from just four diodes.

Step 1: Silicon Diode

A silicon diode is a two-lead semiconductor that gates current flow in one direction.  The symbol below shows how a diode is lined up with the schematic symbol.  The image was taken from http://www.gadgetjq.com/single_fire_tach_adapter_diode.jpg for copyright purposes.  Diodes are used in circuits that convert AC voltages to DC voltages, and also as voltage regulators, clamps, and multipliers.

Current flows in the direction of the arrow.  A few other terms of technical use are:

Forward-biased is when the anode is more positive than the cathode, and reverse-bias is the opposite:  the anode is made more negative in voltage than the cathode.

There are different kinds of diodes, too.  Pin diodes, germanium diodes, schottky diodes, rectifier diodes (p-n junction diodes) name most of them.  In this instructable we're going to work with silicon-based pin diodes, although if you're really curious I'd encourage you trying the different kinds of diodes to see how it all shakes out.

Diodes are pretty cheap.  You can pick up a pack of 50 from Radio Shack for around $3.

Step 2: Test It for Yourself

Go ahead and dig out a few diodes from your tacklebox, toolbox, bead drawer, or whatever you keep all your electronic goodies in and put them in parallel.  Connect your voltmeter to either side and take a reading in ambient light.  I get about 4-5mV in ambient light.

Next, grab your maglight and while still taking a reading shine a focused beam on the diodes and see what your voltmeter says.  In my configuration using the diodes I had at hand, I was able to get more than 100mV from four diodes.  That's not too shabby, especially if you're shuffling that voltage off to a capacitor to either save for later or to build up a larger charge to do something more useful, like light an LED (yeah, like that's more useful) or run your garbage disposal.

You don't have to worry too much about which direction the strip is facing as long as you face the strips all in the same direction.

Step 3: Get Funky

So you're generating voltage with your flashlight and a handful of diodes.....wow.  So what's next?  That's up to you.  You could cover a PCB with them and see how surface area corresponds to voltage, when you get diminishing returns, what the optimum diode to voltage ratio is, etc.   You could add in capacitors....throw in an op amp or even a charge pump and turn mV into V. 

I dropped $5 at R.S. and got two packs of 50 diodes and etched a PCB.  Your designs are endless.

Step 4: Final Thoughts

I hope I was able to share something new with you and that you now have a new-found love for green energy.  Don't get to crazy though; a rooftop of diodes will get you in trouble with your significant other.

Cheers!
-gian

Comments

[charlessenf-gm]

I found this years after you posted it here: https://www.instructables.com/Tiny-Solar-Cell/
Thought it a great idea and posted the following comment - before I discovered the link in that one to this one. So, you deserve the comment:

Out of the box thinking!

[RollandH]

This was a very informative instructable and one of the only things I could find after work on the subject. Just this morning before work I tested a green led taken from a disposable camera with my voltmeter held up near a fluorescent bulb and it produced over a third of a volt. So I've been curious all day about the potential applications. Now a bit ago I read about the p and n connections in which they basically pollute the silicon crystals with differing metals on the p and n side. So I grabbed the only tiny diode (not light emitting) that I had and tested it in the light. I got close to half a volt. Then the thought occurred to me... what if I further 'polluted' each output end of the diode with differing metals? Would that cause greater flow? So I clipped a copper tube to one end and a piece of aluminum foil to the other and tested it again in light with the voltmeter. It jumped up to slightly over a volt! So now I'm more curious than ever and am also wondering why they don't make the diodes with one kind of wire on the p side and a differing kind of wire on the n side? Perhaps some do and if so I am unaware of it but that wouldn't be surprising because I'm fairly new to electronics. Anyway, I appreciate this instructable and want to thank you for furthering my curiosity.

[charlessenf-gm]

" why they don't make the diodes with one kind of wire on the p side and a differing kind of wire on the n side?"

Your experiment is fascinating. Your question may have a simple answer "form follows function" (or Design, in this case).

That is the diode's designers were creating a diode to control the flow of electrons. You, on the other hand, are attempting to generate electrical energy from the "p n" junction.

Quite possibly, folks designing Solar Cells do employ similar techniques involving varying materials to optimize output.

Good thought - worth experimenting with! And, you might look at:
https://www.instructables.com/Tiny-Solar-Cell/?utm...

[SympanS]

useful instructable man!

[Johnk543]

I,ve got 320 mV using only 20 diodes rated 27volt .I'm going to try set them serially and parallel by using more diodes (600 ) to see what voltage and amp I can get out of them .I'll post the result after done.

[FaheemS9]

Hello

I have try this system but not work properly , i was used 130 diodes this show 12 voltage but this temporary after the some time lose voltages and totally 0 voltage why ?

[FaheemS9]

Hello

I have try this system but not work properly , i was used 130 diodes this show 12 voltage but this temporary after the some time lose voltages and totally 0 voltage why ?

[FaheemS9]

Hello

I have try this system but not work properly , i was used 130 diodes this show 12 voltage but this temporary after the some time lose voltages and totally 0 voltage why ?

[FaheemS9]

Hello

I have try this system but not work properly , i was used 130 diodes this show 12 voltage but this temporary after the some time lose voltages and totally 0 voltage why ?

[FaheemS9]

Hello

I have try this system but not work properly , i was used 130 diodes this show 12 voltage but this temporary after the some time lose voltages and totally 0 voltage why ?

[ShahmeerA1]

I have try this system but not with any circut board ,I was used 8 diode but it is not working; Does it not work without circut board.give me anwserplzzzz..........

[Yonatan24]

Ummm

Did you ever hear about perpetuum mobile?

[spinxsunyi]

I am very happy with this tutorial. Then I bought a couple of diodes and connect. Either in series or parallel both have been tried. But somehow did not happen anything. Under direct sunlight, or under lights.

8 diodes connected in series with each other, then given light. then each end connected to a voltmeter. the result is no voltage.

8 diodes connected in parallel with each other. Then given light. then each end connected to a voltmeter. the result is no voltage.

I hope you can help. thank you.

[nevdull]

Hi there,
Sorry to hear you're having problems with reading voltage from your diodes. Make sure your multi/voltmeter is set to mV or auto because you'll likely just get in the 10's to max 100's mV.
Good luck!

[kodama]

Hi, with known V/A cell, how do you determine optimum diode size and reverse/forward bias? Per panel I'd like to use for shading bypass and another to prevent backward creep from batteries overnight

[yhdesai]

u said u used 50 diode
what was voltage and ampere generated

[Razanur]

It's a nice project.
I wanted to add it here, because nobody actually wrote anything about it (and some ppl might be confused by it!):
No, this is not a cheap or convenient method of creating electric power!
The amount of silicon used in diodes is very small and it is not specialized for creating electron flow from photons. You will go way cheaper (in means of Energy per dollar) and way more efficient (in means of space, time, components) if you just use solar cells.
My theory for the seeming limit of 100mV is, that every diode has a voltage drop of 0.5V as well, so this might be a border-effect, which wears of, as soon as you reach 0.1V... Not sure about it though.

[nevdull]

Hi,

Thanks for your comments. I agree with you: diode energy harvesting can't compare to composite solar cells. This is definitely for exploring. As for the limit of 100mV, keep in mind that depending on the electron sinks and sources between the P and N junctions, you can well get diodes with voltage drops as little as 0.3 using a Germanium diode...but as far as I know, that's about it.

Thanks for the comment!

[ENG.MOAMENGABER]

value power plz

[Raymond_Yj]

its because of the light source or the heat?? Any other powerful diode that i can use besides 4148? i would appreciate if u have the complete circuit diagram for this project.