Build a Solar Panel

How to Build a Solar Panel?

The ability to construct a diy solar panel is well within anyone’s reach.  In order to build a solar panel you will require some basic tools and a few hours of time.  Most people will already have the tools and you can get simple instructions right here.  Building a solar panel yourself can save you a lot of money over buying pre-built solar panels.

Basic Tools

There are a few basic tools you will need in order to build a solar panel.  For the easiest type to build, a basic wood box to hold the solar cells, you are going to need tools like a screwdriver, drill and saw.  You will need some type of adhesive to attach the cells to the back of the box.  Silicone glue is a good choice for this.  You will also need some electrical tools like soldering iron and solder, and wire cutters and strippers.  Don’t worry, you won’t have to do any delicate soldering.  All of the electrical work is pretty easy – things like soldering pretty big wires together.  You should be careful anytime you are messing around with electricity, but even if you’ve never soldered before, you should have no problems.

Where to Get Solar Cells?

Building a solar panel is basically just putting a bunch of solar cells together into a box of some kind.  First, you will have to get some solar cells.  The best place to get solar cells is Ebay.  Solar cell auctions are going on all the time.  Look for 3”x6” solar cells – each cell will generate .5 volt and about 3.5 amps.  A panel with 36 cells which will output 18v, 3.5 amps in direct sunlight, is the most common type of home build solar panel.  Search ebay for “solar cells” and you will find lots of auctions for good quality solar cells.  Most auctions are for lots of 100 or 108 cells.  108 cells will produce 3 complete panels of 36 cells each so that is a good way to go.  Be sure to check if the auction is for new, unbroken cells or “grade B” cells.  “Grade B” cells usually have cracks or broken corners.  If you can find “grade B” cells cheap, they can be a great way to save money on the cost of your home build solar panel.  These type of lesser quality cells will output a bit less energy than good quality cells, but they are usually perfectly usable.  They are discards from the major solar panel builders.  No matter whether you buy grade A or B cells, if you can, buy pre-tabbed cells.  Buying pre-tabbed cells will cost a bit more, but it will make the later wiring much easier so it is worth paying a bit more.

Constructing the Box

There are many different kinds of material you can use to build the container for your cells.  For most people, the best choice is wood.  It is easy to work with and you probably have all the tools you need for wood.  First, figure out how you want to lay out the solar cells and then determine the dimensions of the of the container you’ll need to hold the cells.   Plywood will work for the back and ¾” square will work for the sides.  It isn’t critical that you use this exact type of wood, so go with whatever you have on hand or is cheap at the store.  Now, you’ll also need some wood to go into the box to use for attaching the cells.  You’ll attach the cells to this piece of wood and put that piece inside the box.  Fiberboard works fine for this part.  Cut the piece to fit inside the box you built.  A clear cover for the box will protect the cells from the weather, while letting the sun in to generate electricity with the solar cells.  Lexan or plexiglass is a good choice for cover.  Cut it to fit on the panel container.  Now you should screw everything together and paint the wood.  You will also need to drill a hole to run the wires out of the box.

Attach The Cells

Ok, now it is time to attach the cells to the piece of fiberboard.  Silicone glue will do the job well.  Put a dot in the middle of each cell and attach the cells to the fiberboard in the pattern you selected.  Applying just enough glue in the center of the cell will allow the wood to expand and contract with heating and cooling.  Putting glue at each corner, like probably seems the best way to go, can actually cause problems when the wood expands so stick to using only as much as you need right in the center of the cell.  After the glue dries you’re ready to wire.

Wire All of the Cells

Assuming you bought pre-tabbed cells, wiring the cells together should be pretty easy.  If you didn’t buy pre-tabbed cells you will have to solder on tabs before you glue down the cells.  Most panels are 36 cells wired together in series to deliver 18 volts.  Wire all of the cells together in series and then you may want to wire in a diode.  Electricity flowing backwards can be a big problem.  Electricity basically flows from higher voltage to lower voltage.  For example, if you panels produce 18 volts of electricity, the panels will charge 12 volt batteries.  But, what happens if it’s night and the sun isn’t shining?  The panels are producing very little voltage, but the batteries are still at 12v so energy will flow backward from the batteries to the solar panel and actually suck the power out of the batteries!  Some good charge controllers include protection to stop this battery draining, but some simple charge controllers don’t.  If your charge controller doesn’t have this type of protection, putting a diode in your panel will allow electricity to flow in one direction only – out from the panel, but not back into the panel.  The final step is to run the wires out the hole you drilled and fill in the hole with some silicone caulk.  If you want, you can put a connecter on the end of the wires to make connecting and disconnecting the panel easier.

Attaching the Cover

Now you need to put on the clear cover.  Screw the cover on and you are finished with construction!

Testing the Panel

Grab a voltmeter and head out into the sun.  Connect the voltmeter to the panel and see what the reading is.  About 18 volts is perfect.  Congrats, your home build solar panel is complete!

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