How to build your own solar panel

[jerrymrc]

There is nothing hard about building your own panel. When I started I even bought an on line book. Having built a few we are going to build a basic 35 watt panel and show you some options along the way.

Items on the shopping list.

Solar Cells
1/4" hard board
Connecting strips
Small soldering iron (20-25 watt please)
Solder
Wire
Caulking
3/32 glass

These are the basics that will get you going.

All solar cells are about .5 volts each. Now if you break the cell in half each half will still have .5 volts. In order to charge a 12V system you need to start with about 18V or 36 cells wired in series. The back of the cell is + and the front is -

The bigger the cell (for the most part) the the more current (amps) or power (watts) it will make. Also understand that as you lose the sun the voltage will drop and this is why you start with 18V. A good panel will still make power on a somewhat overcast day.

The 35 watt panel we are building is 14x33" It uses 1.5"X 6" cells. I get my cells from member Fred480v on Ebay. 1.5"X 6" or 3" X3" are $50 I have purchased more than one batch at a time from him for $40 each bundle of 36 and that made the shipping free.

These cells are not perfect but at the cost per watt we are not going to complain. To buy panels you are looking at $5-$7 a watt. We can build for $2 a watt.

First up. The cells. you see the front and back. That white pad on the back is our + terminal and the white stripes on the front are our - terminal.

 

[Wil-C]

Absolutely keep this going, I definitely want to learn how to do this. Any source other than ebay for basic cells? $2 a watt, that makes it so much more affordable. This will be a 12V system I guess?

 

[jerrymrc]

Now you must tin both the front and back and our connecting strips. You can buy the strips or since I had some copper foil around that is what I used. I cut it into 1/8" X 2" and tin it. I have already cut my hard board to 14"X 33" I have painted one side with paint and I would suggest that you use white or silver since the panel will get warm and any area that does not have a cell on it is in direct sunlight.

One thing about size. You can make your panel as big as you want but one thing I keep in mind is that I buy the glass at Home Depot and the sizes offered determine my panel size. I do cut my glass to fit but it starts out as 18"X 36"

The cells are very thin and very brittle handle with care. I have a small piece of MDF that is flat to put on the work bench. Tinned leads.

Pics to follow since the server is having issues. Stay tuned.

 

[0007]

I must be missing something here. I see 36 cells @$40/cell(best price). That equals $1440 in cell costs. Divided by the 35 watt output and we have $41/watt. That's a very long way from the estimated cost of $2.00/watt that was in the orginal post.
I'm sure I have missed something somewhere. Unless you mean you are buying enough to do one panel at that price.

Got it, thanks. Ifigured that's where you were going, but my brain wasn't processing the data.

 

[jerrymrc]

I must be missing something here. I see 36 cells @$40/cell(best price). That equals $1440 in cell costs. Divided by the 35 watt output and we have $41/watt. That's a very long way from the estimated cost of $2.00/watt that was in the orginal post.
I'm sure I have missed something somewhere. Unless you mean you are buying enough to do one panel at that price.

I have edited my post to reflect that the $40 is for a bundle of 36. Sorry for the confusion.

This will be for a 12V system. I have no other source at this time for cells.

 

[jerrymrc]

OK back to the panel. We need to tin the cells and attach our strips. I work in pairs of cells. I solder 2 together and attach to the board. Now we are doing a series circuit. + to - to + to - This means we need to go from the top of on to the bottom of the other.

When building this 18X18 cell panel one side will start with a + at the top and the other wth a - at the top. You will see in a few posts. OK tinned wire.

 

[jerrymrc]

Cells that are tinned and with leads attached. I must stress that when you are soldering on the cells to be very light and very quick. This is why some of my soldering does not look the best. I do not want to put allot of heat into the cell as this may damage it.

 

[jerrymrc]

Now lets put the two together. I turn them over and place them about a 1/4 inch apart. Next I put a small crimp in the leads so as to not have the leads pull apart when the sun hits it and it expands. You just need a little slack between the cells.

I use a drill bit or jewelers screwdriver to lift the lead up and then push it down to get my slack. The two cells soldered together and ready to mount on the board. Remember bottom to top to bottom.

 

[jerrymrc]

Time to mount them on the board. I mark the center and just start at the top. I lay the cells on the board and mark the corners. Then remove and lay an 1/8" bead of caulk. I run the bead around just inside the edge and then a zig-zag in the center. This gives the cell some support and a cushion.

Lay the two cells back on the caulk and gently set into the caulk and position.

 

[jerrymrc]

with the cells set into the caulk and ready to be soldered into the panel. Also notice that the top cell has no tabs sticking out of it. That means that the top of that row is Negative. The next row that we place WILL have the leads sticking out of it to mate up with the other side.

You can start any row any way you wish but you just turn your completed 2 cell group upside down for the next row. This will be clearer in a few posts.

 

[jerrymrc]

Now we need to connect the two pairs together. just tin and solder. This is the slow part of building. I do about 3-4 pairs in a night and take a break. Do not forget to put your crimp in.

 

[jerrymrc]

I like to check my work every couple of cells. If you check under the lights in house or garage you will only see Millivolts and if you know what your looking for that is fine. I like to check in the sunlight because it makes it so much easier.

4 cells at .5 volts apiece = 2 volts Yep. Any $5 Voltmeter from Harbor Frieght will do.

 

[jerrymrc]

Now at the top of the panel you have two rows of 18 cells and you need to hook them together. We make a buss to connect the two sides. You can use lead strips or wire but if you use wire you must attach it to the board.

Here are my two sides showing one side has leads on the top and one on the bottom with the strip that will connect them.

 

[jerrymrc]

All soldered up. Also notice that one side starts out + to - and the other is - to +

When you get to the end of each row you will have one side with the leads sticking out of the bottom and one with the leads on the top. It will be a couple of days before we continue so I can finish this part and answer any questions.

 

[jerrymrc]

Just about ready to continue this. Need a couple more days and this will pick back up again. I had a issue I had to attend to the last few days.

 

[AndyC]

Fascinating - I've always been curious about this, but never done it. Please continue when you can, Jerry :bow:

 

[jerrymrc]

Tomorrow we will finish the electrical connections, Install the gasket, cut the glass and seal it up. Here is where we are at.

 

[jerrymrc]

So now we have a bunch of cells mounted on a piece of wood. Fire the electric company and kick back.....:uhoh: Yea...Right. Let's see how we did. 36 cells at .5V each says 18V. Meter says we have a few more than that.

I did an Amp check and into a slightly discharged battery and was showing 1.85 amps and that is a little more than our 35 watt target.

 

[jerrymrc]

Now let us hook up the lower buss. I have attached the two sides and ready to hook it all up.

 

[rochte]

Great thread... Thanks for sharing and please, keep telling us more!

I'm curious to know how the cost per watt of these cells (and the completed panel) compares to the amorphous panels at Harbour Freight.

On sale, their 14"x3" (or so) panel can be purchased for $15 - it had enough juice to run a DC/DC converter, GPS and APRS tracker in full sun (the smallest shadow, though, knocked it out). Not sure the actual ratings of the panel.

 

[jerrymrc]

At this point I drill a hole, tin and solder my leads to the buss. I just use a few feet of wire but you could mount a box with connections on the other side if you wish. A twin banana plug would be nice or just a set of speaker terminals would work.

 

[jerrymrc]

Gasket time. I use 1/8" rubber gasket and give it about 1/8 gap from the sides. This works very well to cushion the glass that is coming next.

 

[jerrymrc]

Gasket in place. having adhesive on one side makes it a snap and one package will do 2 of our panels.

 

[jerrymrc]

close-up of the gasket and buss.

 

[jerrymrc]

Now for more fun and games. I get my glass at Home Depot and it is about $9 for the piece. I like glass allot better than acrylic but to each his own. More in awhile stay tuned.....