Let's Make Robots!

Homemade Solar panels

Charges your robots batteries while its on the move

Hello everyone.

I decided on building a solar panel using solar cells to charge the batteries of my robot while its in use. (so that i have even longer run times.

 

The solar cells are fairly cheap. The ones i used for this project are 52 x 1.9mm  and 78 x 1.9mm cells that need to be tabbed and soldered before they can be used. I will be getting 840mah and 1500mah respectively

Dont worry about packaging. They were packaged in multiple layers of bubblewrapp and polystyrene sheets so they are very secure. 

You might ask yourself as to why i went through all this trouble instead of buying fully functional cells. Well i find it fun an i feel good in the end as i put something together rather than piece parts from a kit together and well its a lot cheaper than buying fully tabbed cells. The initial cost having to buy the flux pen, and tabing wire is always a problem but on the whole i spent $8.50 on tabbing wire, $6.70 on 40 pieces of 52 x 19mm panels, $10.30 on the 78 x 19mm panels. This cost is far cheaper than buying fully tabbed cells of the same specifcation voltage and current outputwise.

My fully tabbed cells. i have another 3 batches on the way from China.           

Tools and equipment.

1. Solar cell. These are available in different sizes and are available on ebay each cell is rated at 0.5v.They are availbale in lots of 40 (just type "polycrystalline solar cell" and they will come up" the 52x 19mm are are rated at 0.14w a piece. In other words 0.5v and 280ma. The 78 x 19mm are rated at 0.25w a piece, in other words 0.5v and 500ma

2. Tabbing wire. This will be used to connect cells in series. (You need this) purchased on ebay.

3. No Clean Flux pen. This will be used to enable better contact between the tabbing wire and cell. You wont be able to tab them without this!

4. Soldering iron. Now people will say that 60w is best. i have been using a 25w iron with no issues. 

5. Solder. I used 60/40 solder for this. 

6. A solid flat surface to work on. I worked on a flat piece of 4mm aluminium. you need a flat surface as these cells are fragile. they break too easily.

How to.

Wet the horizontal white strips on the back and the front to open up a connection. Once stroke on either side is enough. After that put a small dab of solder on the front side at the top of the strip. This is to anchor the tabbing tire to make it easier to solder. 

2. Attach your tabbing wire and heat up the top end to make it hold. Then start sliding the soldering iro nup and down the column until its flat. The tabbing wire should stick to the panel. Do NOT press hard on the panel or it will break!!!

3.Now the back end. Putting these in series involves putting the negative tab wire on the positive part of the 2nd cell much like connecting batteries. You need to put a dab of solder on the entire length of the strip to enable a connection (After wetting it with the flux pen.

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4. Make this into a chain keeping in mind that 1 cell = 0.5v. I am making a 6v panel so i need 12 cells. Test after every 3rd cell by putting it in the sunlight and checking the voltage. I am making a 6v 1500mah panel using 36 cells here. I am mouting it onto a double layer piece of cardboard. Its quite stiff  and light which makes it suitable.

When fully connected in sunlight. (This is at sundown)

Rear View.       Connected to Rover

             

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Thats great.

What about the charger controller?

I have decided to connect them inseries to 12v so i will get 12v 2amps i will then use a lipo battery charger that has automatic chargng when voltage falls below 4.2v per cell. The solar panels will be connected to the lipo charger to charge the batteries and it will control it automatically.