Introduction: DIY Solar Cell From Scratch
Third Prize in the
MAKE ENERGY: A US-Mexico Innovation Challenge
Third Prize in the
Explore Science Contest
Hello! In this instructable I will be showing you how to create a solar cell! I must warn you, the end product does not have any esthetic appeal whatsoever and is far from an professionally produced solar cell, but it works! This instructable will cover everything from gathering materials to measuring the output of your newly created solar cell.
According to Wikipedia a solar cell or photovoltaic cell is “an electrical device that converts the energy of light directly into electricity by the photovoltaic effect. It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as current, voltage, or resistance, vary when exposed to light. Solar cells are the building blocks of photovoltaic modules, otherwise known as solar panels.”
The photovoltaic effect the creation of voltage or electric current in a material upon exposure to light.
Step 1: Gathering Materials
Like any project there is a shopping list, most of these items are household items or tools, and you will most likely already have them. I recommend vendors on eBay for items like the glass plates and titanium dioxide.
- Titanium Dioxide (white powder, often used in make-up)
- 2 Binder clips (to hold the plates together)
- Acetone or rubbing alcohol
- Glass plates*
- Graphite powder/pencil/lubricant stick
- Syringe (not a must, just handy)
- Multi meter
- Cotton pads/swabs
- Alligator clips
- Aluminum profile (or something straight, non-porous like a piece of hard plastic)
- 2 dishes, both shallow
- Demi water (de-mineralized water)
- Raspberry, blueberry or blackberry juice (has to be made directly from the fruit! no processed juices!)
- Iodide solution
The total cost of this project was about 30 dollars for me, as I had quite a lot of the items on the list already.
*These glass plates need to be covered (on one side) in tin oxide (SnO2) this makes the plates conductive which is important. Searching “conductive glass“ on eBay gives some good results.
Step 2: Cleaning the Plates
After you have collected all the items for the solar cell you can start building!
Find a clean surface to work on.
Put some acetone on one of the cotton pads and clean both sides of the first plate. After both sides are cleaned only pick up the plates by the sides! Place the plate on the cotton pad and pull out the multi meter; you want the dial on a setting that detects short circuit. Test the plate for conductivity on the top slide, if the top is conductive place it somewhere clean. If it’s not conductive flip it over and try again, this time you should have the conductive side.
For the other glass plate just repeat the process, clean it on both sides and test it for conductivity. This time you want the conductive side down so it stays as clean as possible. Place this plate to the side as well and put the first plate (conductive side up) back in front of you.
Step 3: Titanium Dioxide
For now you can leave the conductive side down plate to the side, we won’t be needing it until the end.
The conductive side up plate however Is going to be coated in titanium dioxide. First take one of the dishes and pour in a little water. Next, start adding a little titanium dioxide to the water, frequently stirring. You want to remove all the lumps from the titanium dioxide. You will know you have the right consistency when the liquid turn into almost a goo.
Once you have made this titanium dioxide “goo” take a little out of the bowl with the spoon and place it on the plate, try to spread it out a bit but don’t get to close to the edges.
Now we want to equally cover the entire surface. We are going to achieve this by place 2 items slightly taller than the plate on either side of the plate (I used 2 stacked plates) and going over it with the aluminum profile or whatever you chose as your “straight, non-porous material. Doing this we cover the entire surface in an equal layer. If it spills a bit over don’t worry about it.
Once the plate is covered, we need to “bake” the titanium dioxide to the plate. Carefully move you plate to your cooktop or hotplate. Slowly warm it up so the glass has no chance of breaking. When it’s up to temperature leave it for a few hours so it has the chance to bake onto the plate.
Step 4: Finishing Up the Plates
Once the titanium dioxide is baked on we are only about 15 minutes away from a solar cell.
Take the berry juice and put it in the other shallow dish. Put the plate in with it so the juice covers the titanium dioxide. Leave this to soak for about 10 minutes. The berry juice/titanium dioxide is what produces the electrical current, When light hits the juice it creates a negative electron and a positive "hole" and normally speaking these would just bind to become neutral again. Instead of binding the titanium dioxide transports the electron to the terminal (alligator clip) which transports it further to the rest of the circuit.
In the meantime go back to the plate that was put aside (conductive side down). Flip it over and clean the surface one last time with a cotton swab and acetone. Now take the graphite pencil/lubricant and cover the enite surface of the CONDUCTIVE side with graphite.
Go back to the titanium dioxide plate, take it out of the juice and rinse it with demi water. To get all the liquids off DAB it with a cotton pad. I was so stupid as to wipe the plate; most of the titanium dioxide came off my plate. Don’t make the same mistake!
Note: This step is not really well documented with pictures. The picture shows the “graphite plate” covered in graphite powder. This is not how you want you slide, you need to spread it out and rub it into the plate.
Step 5: Putting It All Together
After the last step the plates are ready to be put together. Place the plates on each other but leave about half a centimeter on both plates exposed so you can attach it to the alligator clips (see first and second picture).
Hold the plates together with the binder clips; place them on the sides. There is one last thing we need to do to get good conductivity between the plates. Take off one of the binder clips again and put a few drops of the iodide solution on the sides of your creation so it gets between the plates, this will successfully electrically bond the plates. Absorb any iodide solution that did not go in between the plates with a cotton swab.
Congratulations! You have now created a solar cell!
You can measure the output of the cell by attaching alligator clips to both of the exposed parts of the plate and to the leads of the voltmeter (dial now set to millivolts). mine generates about 25 millivolts when exposed directly to sunlight (simulated with a lamp)
You have now created a working solar cell!
be the start of something bigger, one individual cell does not produce a lot of electricity but if you were to make multiple larger versions of these it could really produce quite some electricity. Use your imagination!
Feel free to leave any suggestions in the comment section!
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