Solar panels are very expensive to buy but with this instructable it’s much cheaper.

you can make one larger panel or several little ones. The larger the panel, the more watt you get.

Supplies

-materials :

-electronics:

I have bought a diy kit https://www.mrwatt.eu/en/shop/diy-solar-photovoltaic-cells-kits/polycrystalline- photovoltaic-solar-diy-kits/diy-70w-solar-kit-composed-by-36-poly-solar-cells-3x6-inches-76x156-mm-a-grade-provided-with-cmp12-and-welding-assembly-kit.html, but you can also buy them separately

polycrystaline solar cells
tab wire
a flux pen
a converter
a diode
stranded wire (not in the kit)

-other materials:

a plywood panel (41.2 cm x 48 cm x 0.8 cm / 16.22 in x 18.9 in x 0.32 in )
spruce bar (35 mm x 18 mm x 1712 mm / 1.38 in x 0.71 in x 67.4 in
4 washers + small screws for the washers
8 screws
white paint
plexiglass

-tools:

a 60-80 watt soldering iron
tin solder wire
a paint brush
a saw
sandpaper
a pencil
a drill
2 bores for the screws
a folding/roll meter (something to measure)

Step 1: Measure, Saw and Sand

Firstly, measure and mark off the pieces corresponding to the first photo from the spruce bar. After that, sand all the pieces, but try to sand it off as little as possible. Only the splinters have to come off. Make sure you don't round the corners too hard. Sand also the plywood panel off as little as possible.

Step 2: Drilling and Hang Together

Bore one hole in each corner of the two 41,2 cm / 16.22 in pieces. After that you take the 8 screws and you screw the fives into the pre-drilled holes. Make sure you become a rectangle as shown in the pictures.

Step 3: Painting

It is best to use white paint because it makes the solar panel heat up less. You must paint the just made rectangle and the plywood panel. It is best to paint everything 2 or 3 times, I have paint everything 3 times. between you paint you must sand of as little as possible.

Step 4: Soldering

Now it’s time to do the most important thing of the solar panel, namely the soldering of the solar panels. You must sold on the thick lines of the solar panels. To connect the solar panels you use tab wire. Cut 4 pieces of tab wire (look to the first picture for the length). You have to connect the thick lines on the back side with the front side of the next solar panel with the tab wire. Look to the pictures for clarification. in my panel, I connected 2 times 5 panels in a row. At the 2 extremes you must solder tab wire ( look to the last picture for the length.)

Step 5: Paste and Solder

Draw the lines as in the first picture on the white painted plywood panel, the yellow lines are the most important. Cut 2 times a piece of tab wire with the length of 15.6 cm / 6.14 in and 1 time a piece of tab wire with the length of 33.2 cm / 13.07 in. Paste the 33.2 cm / 13.07 in long piece on one side and the 2 15.6 cm / 6.14 in long pieces on the other side like picture 7 and 8 with wood glue. After that you take the 2 rows of five solar cells and you paste them in the yellow rectangles with wood glue. Then you solder the excellent tab wire on the glued tab wire. Like that, you connect the 2 rows together( picture 12, 13 and 14 ).

Step 6: Glue, Drill and Connect

Take the wooden rectangular frame and paste it on the plywood panel. Let it dry. You drill 1 hole in the middle of the frame on the side where you stuck 2 pieces of tab wire. After that you cut of 3 pieces of stranded wire: 2 black pieces and 1 red piece. Connect 1 piece of black stranded wire with the negatieve pole of the solar panel and 1 red piece with the positieve pole (You must solder it). Then you take the 2 pieces of black stranded wire and the diode. After that you test witch is the + and - pole of the diode(https://www.fluke.com/en-us/learn/blog/digital-multimeters/how-to-test-diodes). You must connect the black stranded wire that hangs on the panel with the + pole of the diode and the other piece of black stranded wire you must connect with the - pole of the diode. Take the converter and hang the red wire on the + pole and the black wire on the - pole of the converter.

Step 7: Cut, Drill and Attach

Now you take the plexiglass and cut a rectangle from 41.2 cm x 48 cm / 16.22 in x 18.90 in . After that you lay the plexiglass on the solar panel and you drill 4 holes (not to big ) and you turn the screws with the washers into the holes. Normally the plexiglass hang solid on the solar panel. The last step is to kit of the edges of the plexiglass so that your solar panel is waterproof.