A solar cell, in itself, is of little value in our energy consumptive world, but when you combine many cells and hook them all together into a full panel you can realize a great deal of energy. Indeed, many homeowners have managed to run their whole house on solar power. Most households use between 500 to 1000 kwh per month. One solar panel produces about 100 to 150 kw of power.
Here’s a quick glimpse of what to expect, in terms of power needs, if you use 500kwh of power in a month…you’ll need 3800 Watts of power (thirty-eight – 100 Watt solar panels or twenty-six 150 Watt panels) and roughly twenty 12VDC, 100Ah deep cycle batteries (batteries incase you plan to use electricity when the sun is not shining).
Here’s a basic spec sheet of the materials needed to build a solar panel using a collection of solar cells.
One 48 x 48 x 1/8 inch Acrylite UV stabilized transparent sheet; this is used in place of the glass top sheet. Lexan could also be used.
One 48 x 48 x 3/16 inch ABS white sheet.
Four 72 x 1/4 x 1/4 inch clear extruded acrylic bars.
Adhesive glue.
Silicone sealant/adhesive.
Two Eight ounce Rosin core solders.
ERC81S-004 40V, 5A Schottky Barrier Diode.
Five .060 x .002 inch by 25 feet solar cell PV tinned interconnection ribbon.
36 Monocrystalline 6 inch (156mm) solar cell rated at .5VDC, 6 Amp Peak.
Four-position dual row barrier strip.
Sixteen #8 insulated ring tongue terminals.
Twelve gauge hookup wire black insulator and twelve guage hookup wire red insulator.
One or more 3 x 2 x 1 inch project enclosure box.
Crimping tool.
40-Watt soldering iron.
-Optional-
About any DC voltage measuring capable multimeter will suffice.
Variable temperature heat gun.
28 square feet of .018 inch thick Ethylene Vinyl Acetate (EVA) sheet -OR- UV resistant Surlyn sheet. NOTE: EVA sheet shrinks as it is heated; hence 28 square feet is recommended versus 20 square feet.
One of the big reasons more and more people are adopting solar power is to “go green” or reduce their carbon footprint since studies have been conducted revealing that buildings, houses (or residences) contribute something in the neighborhood of 20,000 pounds of carbon dioxide per year each (you may not have a carbon dioxide generator where you live, but if you consume electricity, natural gas, water, sewer service and so on then those “services” create carbon dioxide as a byproduct of what you are consuming). Others may be adopting solar power because they have no choice (maybe you live on an island, for instance, where there is no power).
Building It:
Step 1:
Grab a multimeter capable of measuring fractions of DC voltage and your collection of solar cells.
Position a light source near your collection of solar cells; this will enable to you get a consistent measurement of voltage output of each one of your solar cells.
Step 2:
Set the multimeter to measure DC voltage.
Place the negative test lead (usually black) on the side of the solar cell which indicates negative voltage (usually the front).
Place the positive test lead (usually red) on the side of the solar cell which indicates positive voltage (usually the back).
Observe what the maximum voltage output is. Don’t move the solar cell around to try to get a higher reading since you will be grouping the solar cells together according to how much voltage they generate at the same position from your light source.
Separate your solar cells into groupings of .05 volt increments as you are taking voltage measurements.
This will allow you to take maximum advantage of solar cell output by grouping solar cells together (each group would be a solar panel). For example, if you had 35 solar cells which had an output of .45 volts and you had one which had an output of .35 volts, the output of your solar panel will suffer.
Step 3:
We need to connect our solar cells together with tinned interconnection wire. In order to do this, we’ll need to take the spool of interconnection wire and cut it into 10.5 inch lengths for the six inch solar cells.
Step 4:
Each length of tinned interconnection wire must have solder added to it. This is done by adding solder to 5.25 inches of the wire starting at one end. Then flip the wire length over and add solder to 5.25 inches of the wire starting at the opposite end.
Step 5:
Solder a length of the interconnection wire to each connection strip that is on the front of each solar cell
Step 6:
Connecting solar cells together in series using the Powermax six inch solar cells uses a unique approach where all of the solar cells are soldered together in a zig-zag pattern to minimize the amount of interconnection wire used.
Step 7:
In order to solder the solar cells together, one will be placed face-down.
Step 8:
Take another solar cell, face down, and place the interconnection wires on top of the previous solar cell (leave approximately 1/16 inch space between the solar cells) and solder those interconnection wires to the previous solar cell.
Step 9:
Now that you’ve seen how to solder solar cells together, you’ll need to know the sequence of soldering the 36 solar cells together into a compact form.
Step 10:
While it is not required, it is recommended that you sandwich the soldered solar cells inside of a protective thermoplastic material such as ethylene vinyl acetate (EVA) sheet or UV resistant Surlyn sheet. Over time, if there is oxygen or other contaminants inside the solar panel, your solar cells will degrade prematurely. If you have one of those types of sheet, place the sheet over the solar cells you’ve just soldered together and use the heat gun on the sheet so that it adheres to the solar cells.
Place the solar cells on top of white paper and then solder them together in advance of heating EVA sheet onto them. The reason for this is that the EVA sheet is a very adhesive material when heated (it also becomes approximately 100% transparent after heating). When flipping over the solar panel in a cardboard frame (so that the other side can have EVA sheet applied to it), the paper can be easily removed; without the paper between the solar panel and the cardboard it would be necessary to peel the inverted EVA sheet and solar panel from the rigid cardboard causing damage to individual solar cells.
You will want to over cut the sheet since it will shrink as it is heated.
Step 11:
Carefully turn the sheet of solar cells over, place the sheet over the top of the solar cells and use the heat gun on the sheet so that it adheres to the solar cells and the sheet.
Step 12:
Take the 48 x 48 x 3/16 inch ABS white sheet and, using a cutting tool, cut it down to a 38 5/16 x 38 5/16 x 3/16 inch sheet. Then drill a 5/16 inch hole through the sheet six inches from the right-top edge and one inch down from the right-top edge.
Step 13:
Solder approximately 3 inches of the color-coded wire to the appropriate positive and negative interconnection wire on the #1 and #36 solar cells. Push the other end of the wires through the 5/16 inch drilled hole.
Step 14:
Solder approximately 3 inches of the color-coded wire to the appropriate positive and negative interconnection wire on the #1 and #36 solar cells. Push the other end of the wires through the 5/16 inch drilled hole.
Step 15:
Cut two 72 x 1/4 x 1/4 inch clear extruded acrylic bars to a length of 38.3125 inch. Cut the remaining two 72 x 1/4 x 1/4 inch clear extruded acrylic bars to a length of 37.8125 inch.
Step 16:
Glue one 38.3125 inch clear extruded acrylic bar to the top of the ABS white sheet, lining the bar up with the edge of the ABS white sheet. Allow the glue to dry. Then take the second 38.3125 inch clear extruded acrylic bar to the bottom of the ABS white sheet, lining the bar up with the edge of the ABS white sheet. Allow the glue to dry.
Step 17:
Cut the remaining clear extruded acrylic bar into 1 x 1/4 x 1/4 inch blocks. Glue each block, centered, in between each solar cell in an alternating pattern (this will provide strength to the solar panel).
Step 18:
Take the 48 x 48 x 1/8 inch Acrylite UV stabilized transparent sheet and, using a cutting tool, cut it down to a 38 5/16 x 38 5/16 x 3/16 inch sheet. Place glue along the top of the four acrylic bars which were glued to the ABS white sheet. Place glue on top of each of the 1 x 1/4 x 1/4 inch blocks. Line up the Acrylite sheet with the edges of the four acrylic bars and place it firmly on top. Allow the glue to dry.
You’re done. Optionally you may want to protect your panel from reverse current as this can damage the cells. Assuming you don’t have a charge controller, you’ll need to add a rectifier diode to one of the wires coming out of your solar panel to block reverse current. This section will focus on adding the rectifier diode to the back of the solar panel.
Drill one 5/16 inch hole in the bottom of the 3 x 2 x 1 inch project enclosure box. Drill another 5/16 inch hole into the side of the box. Apply glue to the back of the box. Feed the wire, sticking out of the back of the solar panel, through the bottom hole of the box. Seat the box firmly onto the back of the panel and allow it to dry.
Assemble the junction block with wire and the diode.
Finally, apply enough of the Silicone sealant/adhesive to fill in the hole in the bottom and side of the enclosure box. Allow the sealant/adhesive to dry.
