Introduction: My Home Made Solar Cell

how to build a copper oxide solar cell with copper, glue, water, backing soda and a CD case
activate annotation on video for more information in english. coming soon a brief tutorial
The power output is less than 1mW but is measurable, help me to improve it!
Please excuse the errors in translation


pcaspian (author)2015-08-04

i like this :)

Berserk87 (author)2009-05-02

am i looking at this correctly....70V, 70? wow. what kinda amps do you get from that?

alessiof76 (author)Berserk872009-05-02

I am sorry but are only 70mv, 100mv with sunlight . It is the first cell that I have built I hope to improve it with your help

bobtannica (author)alessiof762009-06-21

As a follow up... 70mv at what amperage? BTW, very good 'able.

Spook-rabbit (author)bobtannica2009-08-22

well the amperage would depend entirely on what you hook up to it wouldn't it?

Voltage = Amperage x Resistance, wouldn't the Voltage be constant, but reliant on the sun light?

CoolKoon (author)Spook-rabbit2009-12-18

Not exactly. Ohm's law you're quoting anticipates an ideal power source (which would supply an unlimited amount of current and no matter how much power you draw the voltage won't drop). So in this case it's 70mV to 100 mV open-circuit voltage, that is voltage you measure with your voltmeter when you don't connect anything to the source. If you'd connect any load to the cell (even a VERY small one), the voltage would drop. This happens to every real electric source (even you wall plug, but the fuses prevent you from doing this as else the lines in your wall would get too hot from the overcurrent and burn down your house). You can't test it with your 110/230V wall sockets, but with an adaptor you can. Just measure the voltage coming out of it without connecting it to any load and then connect a load. The latter will be lower.
As for amperage, there's a maximum amount of current a power source can supply. It depends on the turns of the coiling, strength of the magnet surrounding the coil, internal resistance of the wire, amount of power that can be harnessed to turn the generator (the bigger load you connect to it the harder it becomes to turn it) etc. The same applies to solar cells, just the relations are a bit different. So for solar cells they measure the maximal current it can supply by connecting the ammeter in series with the solar cell, effectively short-circuiting it (NEVER EVER do this with your wall plug unless you want to risk fire and a destroyed ammeter). This short-circuit current was probably the parameter bobtannica was asking for.

tech-king (author)alessiof762009-09-10

from what i know, you cant get much more; copper oxide cells are very inefficient.

Berserk87 (author)alessiof762009-05-03

that makes more sense, haha.

yourmy1004 (author)2009-09-09

It's cool... really 70v right.. but It's a low current. it can't working to turn on the led. you have to choice between current and voltage.

analogBob (author)2009-05-17

Hi, one other thing. I read a little about copper oxide. I think the black stuff is copper(II) oxide, and the semiconductor you keep is copper(I) oxide. Is sounds like copper(II) oxide is very, very nasty stuff. I think you should be wearing gloves for handling it, and a respirator to not breath in the little flakes. I don't want to hear you've gotten sick :)

analogBob (author)2009-05-17

Yes, I think a wire would make a much better electrode than just another copper plate. It lets most of the light past, but can come close to contacting nearly all the surface. A piece of screen might be very nice for this. I'm thinking about the kind of screen they make for rabbit cages, maybe 1cm x 1cm squares, you can get at the hardware store. The metal that it is made of is certainly more resistive than copper, but since it would be so easy to get the contact to spread over the entire cell, it might mean effectively a lower contact resistance, and would be easy to make. Anyway, I think this is a cool project. I would like to make one as well, and maybe experiment with different electrolytes. For example, how about Jello, with salt in it? If you make it thick enough, it might be a nice way to keep the anode and cathode from contacting each other.

analogBob (author)2009-05-16

This is very exciting. Do you think you could get some improvement if the copper surface was roughed-up, before heating? With a power sander and/or rasp, for example. Just wonder if this would create more surface area of copper oxide, so that you would get more electron-hole pairs, and more power. Great job.

alessiof76 (author)analogBob2009-05-16

Thanks! nice idea Ill try! I was thinking about wrap the plate of oxide with a wire of pure copper (isolated from plate) to lower internal resistance of the cell

Berserk87 (author)2009-05-14

i want to see you make 20 of these things, and put them all in series. see how much power you can get from these things.

alessiof76 (author)Berserk872009-05-16

I prefer find the optimal setup before building so many cells ;)

alessiof76 (author)2009-05-03

I have just published a instructables:

Bongmaster (author)2009-05-02

got a picture version of this ible?

stuuf (author)Bongmaster2009-05-02

Or a text version? I don't feel like watching the video right now just because you were too lazy to type anything.

Kiteman (author)stuuf2009-05-03

(There's a first - somebody on the intertubes too lazy to watch a video...)

stuuf (author)Kiteman2009-05-03

I didn't say I was too lazy to watch it; I just didn't have time to watch the whole thing and wanted to read a tiny bit of information about it other than "my home made solar cell." Maybe I'm old-fashioned, but I find the traditional text/image instructables a lot easier to use, especially when they have more than 4 or 5 steps and you have to stop and re-read something. Scrolling through a web page of text and graphics is much easier than scrubbing through a youtube video trying to find a specific passage of speech. And you can't zoom in on a youtube frame if something isn't clear enough at 480x360 pixels like you can with instructable images (the little "i" link in the corner is your best friend for large schematics or blurry camera phone photos). I'm not saying videos are bad, but they should be an augmentation of, not a substitute for, written instructions. And if you insist on hosing your video on youtube you should really think about posting a few higher resolution images somewhere else.

alessiof76 (author)stuuf2009-05-02

If you activate annotation on youtube video you will find some explanation in english

hominid (author)stuuf2009-05-02

Well, on the other hand, there was good effort in the production of the video, so it's not really laziness, in my opinion. Well done.

alessiof76 (author)Bongmaster2009-05-02

I am going to do it!

thearchitect (author)2009-05-03

Impressive stuff! Great job, thanks for sharing!.. I am looking forward to your step by step instructable! K.

alessiof76 (author)thearchitect2009-05-03

Many thank

Kiteman (author)2009-05-03

Are the chemicals used up by the process? If so, how long does the cell last before it needs refilling or refreshing? (Babelfish says;) I prodotti chimici sono consumati tramite il processo? In caso affermativo, quanto tempo la cellula dura prima che debba riempire o rinfrescare?

alessiof76 (author)Kiteman2009-05-03

i report from :
Cuprous oxide is a type of material called a semiconductor. A semiconductor is in between a conductor, where electricity can flow freely, and an insulator, where electrons are bound tightly to their atoms and do not flow freely.

In a semiconductor, there is a gap, called a bandgap between the electrons that are bound tightly to the atom, and the electrons that are farther from the atom, which can move freely and conduct electricity.

Electrons cannot stay inside the bandgap. An electron cannot gain just a little bit of energy and move away from the atom's nucleus into the bandgap. An electron must gain enough energy to move farther away from the nucleus, outside of the bandgap.

Similarly, an electron outside the bandgap cannot lose a little bit of energy and fall just a little bit closer to the nucleus. It must lose enough energy to fall past the bandgap into the area where electrons are allowed.

When sunlight hits the electrons in the cuprous oxide, some of the electrons gain enough energy from the sunlight to jump past the bandgap and become free to conduct electricity.

The free electrons move into the saltwater, then into the clean copper plate, into the wire, through the meter, and back to the cuprous oxide plate.

As the electrons move through the meter, they perform the work needed to move the needle. When a shadow falls on the solar cell, fewer electrons move through the meter, and the needle dips back down.

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