Clean Energy Series: project solar cells

Solar Energy

This post acted as a scientific journal into my research and attempt to generate clean energy from solar cells.

Introduction:

The solar cell has been around for centuries ever since the discovery of the Photo-Electric Effect by Albert Einstein, which won him the noble pieces prize. To put it in a normal term, the Photo-Electric Effect explained that light is a particle and it can knock the electron off an atom. As a result, silicon, a semiconductor on the solar cell, can produce a potential difference when it is exposed to light. However, it can also work in reverse. Such that, when it is given potential difference, it will give off light (not very bright Light). So, we say that solar cell is an LED and LED is a solar cell. It just a matter of efficiency in its function.

A single solar cell does not produce a very high voltage ( I'm using 0.4v cell ), so you might need to connect a bunch of them in series (to add up the voltage) and parallel (to add up the current). As a result, you have a solar panel like the commercial one. That is not it, you will need a solar controller (pwm, mppt...), Batteries, a power inverter, and other components (cable, fuse, breaker...).

A solar panel can be quite expensive depending on its work done, but solar cells are not. Apparently, Chines companies are able to mass-produce them at a very low price for us sciences geek. So, my attempt is to create solar panels and build the system. However, I will buy other necessary parts(the solar cell, solar controller, battery, the power inverter...) locally and online. 

Solar Cell:

The most difficult yet exiting part. When soldering the cell together, we have to modify and plane the connection first. In series, the cell will stack up voltages while keeping the current the same. Then, In a parallel connection, the cell will accumulate the current instant. With this in mind, I go with the highest voltage with the available space. Resulting in 7v and 0.06mA for one panel.  

Practices:

The soldering technique requires no experience. Well, we will need flux, bus wire, and solder. We cut a two-cells length bus wire and solder it to each cell on the blue side. after that, we connect them to each other back. 

Moving is a little bit tricky. the cells are placed on board (mainly the front glass of the panel). Testing is done to make sure no part is disconnected. Then, we mix epoxy resin according to the instruction and pure it on to the edges. at that same time, we place the back panel and press to even out the epoxy for several minutes.

Analysis:

Normally, It works but sometimes it doesn't. About two or three mounts of using three DIY solar panels, two of them are down. The acrylic glass deformed under the intense heat of the sun. A future improvement would be:

Use a thicker acrylic or use an actual glass(which will cost more). 

Strategic 1 (first Attempt)

  I  Instruments :

        1. Solar cell: (52 * 26mm) 0.5v and 0.45A in sunny condition.

        2. Bus wire: (1.8x0.16mm) for connecting the cells.

        3. Flux: for better soldering.

        4. Soldering station: including solder and lead.

        5. (Opt) Fiberglass or acrylic glass: it is the case of the solar panel

        6. Epoxy: to seal the panel while letting light pass through.

  II Layout and design:

        The solar cell has a positive terminal on the white side and a negative terminal on the gray side. The maximum output of each cell is 0.5v and 0.45A ( under direct sunlight). If we connect the cell in series, the voltage will accumulate while leaving the current the same. However, if we connect them in parallel, the voltage will remain the same while the current accumulate. 

        My design of the solar panel is based on the size of the acrylic that I have and trying to prioritize maximizing the voltage. 

        I will connect 14 cells in series to create 4 sets of 7v 0.45A. After that, I will connect them in parallel to obtain 7v 1.8A ( in theory ).

  II  Procedure: 

• Step one :

You will need to cut the bus wire into a small length of two cells so that we can solder the positive side of one cell to the negative side of another cell. After that, we are ready to solder the bus wires to the white side of the cell (-).

• Step Two:

Now, Apply flux to the (-) side of the cell. Use the soldering iron to gently push and stroke the bus to the cell. It is wise to use weight to hold the bus wire down on the other end as you working on soldering.

• Step Three:

After you have finished with all the cells, arrange the cells into a row of 14 with the gray part and bus wire on top. It is good to put it on the acrylic glass so you don't have to move it later. Apply flux to the white stripe, and solder them together. Continue with to get 4 sets of 14 cells.

• Step Four:

You will get 4 sets of 14 cells that have the same terminal facing the same way. Then using the bus wire connect the same terminal together and left them with a long strand at the end. In my case, I just used a bigger bus wire, but the small bus wire still works the same.

• Step Five:

I used epoxy resin to seal both acrylic glasses together because they provide a good seal. If you have more, you should apply it entirely. In my case, I did not have enough epoxy, so I just spread it around the corner.

    IV. Result

The solar panel that I made was not a good or efficient type. It lacks the power to generate or charge a battery. Moreover, It needed to be in direct contact with sunlight all the time. 

But It works. I was able to power a small motor and LEDs, but not at the same time.

For more info contact:

lychheang008@gmail.com