Instructables

Make a high powered solar panel from broken solar cells

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Step 1: Tools needed

To start making solar panels from broken solar cells you need a few things.
1. 15-25 watt soldering iron
2. Light duty 60/40 electronics rosin core solder (radio shack $5.00 for a roll). You can use a silver solder, but I think its too expensive, and the difference in resistance is minimal. So I just use regular old electronics solder.
3. Multimeter
4. Pencil eraser
5. Solar tabbing pre tinned ribbing (ebay 100 feet is like $20 bucks)
6. A good flat sturdy working surface ( I use a piece of glass, but whatever you have will do)




Step 2: Overview

Picture of Overview
First get some solar sells.
Solar Cell Grab Bag
Electronics goldmine Solar cellsEbay
Thats just a few examples of where you can get solar cells, but it gives you a start.

First lest discuss parallel and series wiring

Parallel wiring increases amperage and voltage stays the same. Each cell in a parallel circuit is wired positive to positive and negative to negative.

Series wiring (mostly what you will use for solar cells} increases voltage and amperage stay the same. Each cell in a series circuit is wired positive to negative, the remaining positive and negative are you leads. You'll notice batteries in flashlights installed in series.

Now that you have your batch of solar cells we can get started!
First separate the cells in approximate similar sizes.
Remember if your wiring a group of cells together in series, the smallest cell in the circuit will dictate your panels amperage. Regardless of the size of your cells, each will produce about .5 volts. The bigger the cell typically the more ampreage you will get. So you wouldn't want five 6" cells with one 1" cell in series, because you would loose the amperage of the bigger cells and only output the amperage of the 1" cell. Basically try to keep the cells around the same size.

Most solar cells ( poly and mono crystalline) the positive side is the back of the cell and the negative is the front of the cell.

Step 3: Getting started

Now that you have your batch of solar cells you must determine if each cell has tabbing on the busbar. If if does continue to the next step.

If your cell has no tabbing you must first use a pencil eraser to clean the surface of the busbar. Use a gentle hand as poly and monocrystalline cells are extremely fragile. Rubbing too hard will break the cell. Some of the dark spots on the busbar will hinder the solder from sticking so try to get these off. Don't go crazy if you can't, as long as a descent amount of solder sticks you are OK. The more you use the eraser the better.

Next you must tin your soldering iron with a nice blob of solder, and wait a few seconds until it stops smoking(some of the rosin burns off), then run it down the busbar. Don't beat yourself if you can't get every spot to stick as long as you can get a few spots you're good.

Now cut a piece of tabbing and use your soldering iron to melt the tabbing into the tinned busbar. Don't press down too hard let the soldering iron do the job. Thats why I suggest using a 25 watt minimum soldering iron so that you don't feel the need to press down on the cell so much.

Now that you tinned and tabbed your first cell continue and do the rest.

Now you must solder a lead to the back of the cell. Most polycrystalline cells have a dark area on the back, this is where you solder to. MonoCrystalline cells usually have small squares where you need to solder to. Just like before start by tinning your soldering iron with a good blob of solder and apply it to the underside of the cell directly under the busbar (makes it easier to line up the cells later). Then cut a small 1.5 inch of tabbing and melt it into the solder.

now that you have your leads soldered to the cell you are ready to move on to the next step.

Step 4: Wiring the cells in series

Now we can start wiring the cells in series. Using the tab we soldered to the back of each cell will now be used to connect to the front of the next cell.

Line them up and melt the tabbing from the underside tab on one cell to the top of the next cell. Keep doing this and you can get as many volts as you want. Remember if you don't plan on using a charge controller you will need to install a reverse flow diode on the positive side to prevent the batteries from draining during the night. You can get them at radioshack, or ebay or where ever you choose.

Thats basically all there is to it. Then all you have to do is make an enclosure of your liking, seal it all up and you have yourself a solar panel. I used a piece of painted plywood some pine peices for a frame and a piece of plexyglass all sealed together with silicone.
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snernz7 days ago

stove. HA HA

zachninme6 years ago
Wow, that's easy: thanks! How do you know positive from negative?
mattfelice (author)  zachninme6 years ago
With all mono and poly crystalline cells the bottom is positive and the top is negative. Or you could just use a multimeter.
But, how do you tell bottom from top wo/ a multimeter?
mattfelice (author)  zachninme6 years ago
When I say bottom I mean underneath or the back, the grey side, sorry about that
How many volts to amps can you expect from such an arrangement thanks Dave'

I realize this is an old thread but it still seems pertinent. If anyone is following,I am wondering if there are any current *haha threads going. And, so I don't lose the thought, could one utilize graphite as a conductor? Thanks.

Why does the tabbing need to go all the way across the top? I mean as opposed to just cleaning the end of the busbar and soldering a small tab to it? Sorry i've never seen a solar cell. Also if a shard of cell doesn't have a dark spot on the back side, is it worthless, no place to solder?
About how much money did this run you? Am I crazy to consider powering a chunk of my home using broken PV's?
johnhearty3 years ago
where can i get those materials?please because we have a project in physics
cheesphht5 years ago
The hardest thing for me to build is the protective encapsulator. Do you build it out of glass or poly? and how was it put together? Or just direct me to the site where instructions to build such an enclosure is available. I want it strong enough to sustain winds but also light enough to put on by telescope's tracking device during the day.
There is a clear silicon two part many home builders use; but it runs around 50.00 a can. It is mixed and poured on the panel while it is face down and a brush is used to spread it.
mattfelice (author)  cheesphht5 years ago
i just made a simple wood frame painted, caulked, with a plexi top
Thank you mattfelice for answers about broken cells and panels. For new guys this is a critical part of making your own panels. Yours is the best statement I have found on the web.... ps/ What's the minimum size (% of a broken/chipped cell) I should use in a panel? Does the size of a broken cell used in a panel matter? If so, what's the rule? Thanks in advance
There really is no minimum size, you just have to remember that a couple of solar cells wired in series is only as strong as their weakest link. So if you wired a piece that was producing 200 milliamps in series with some that produce 1.5 amps it's only going to produce 200 milliamps. So if you use small ones, make sure they're only in series with other small ones.
fat643 years ago
I just ordered some broken pieces to sweden for a first hands on experiment. Taking the time to document this is what generates real wealth, thanks for sharing matt. 35 Watts sounds impressive for that, where in the world do you live btw? :)
Hello,...can I charge a bank of say six battries with this?.and if so how long in good sun?..I'm old and new to all this solar bussiness,and really hoping this old dog can learn a few new things,Thanks John
lampajoo4 years ago
Could I use regular copper wire instead of the ribbon?
mattfelice (author)  lampajoo4 years ago
Sure. Copper wire should work fine
conora2b5 years ago
Hi Matt
this is a really great guide but im kind off stuck on my own project

I am running a 24V battery bank for my wind turbine and want to add solar to the same bank so far i have bought 110 3"x6" solar cells rated as follows,
0.5v x 3.5a = 1.75w each

this is what im thinking off so far please correct me if im wrong in any part of it
to get 24V i need 48 cells in series and 2 sets in parallel (94 cells in total 24V + 7a) to make the most of my cells im thinking of building a 26.5V panel (104 cells in total 26.5V+7a)

is this the right way to go about it or should i lower the volts and increase the amps going to my battery bank and if so will it still store a a 24 v charge?
blacmis5 years ago
There is a VERY informative book "build your own solar panel" by Phillip Hurley that would answer every question on this thread and more. If you really want to build a solar panel and make it easy and be confident doing it. Check the book out.
Wow, that looks kind of hard, and looks like you have to be concentrating a lot not to mess up. Nice job!
mattfelice (author)  GorillazMiko6 years ago
Yeah, what makes it hard is how thin and fragile the cells are. The first batch I got, I couldn't believe how thin they were.
hey, so the top of the cells are negative and the bottom is positive? ive seen a few being constructed and the engineer always just soldered the top two ribbons and nothing underneath. am i seeing things right? also great project, im trying to do the same but i can't believe how thin theses are. im trying to connect about 40 of theses in series but its hard to know what the best steps are to make them into one huge panel. aslo which is the best way to arrange them, parrallel or in series? thanks, Mike
How Many Volts do you need?, amps? Series gives you more volts and parallel gives you more amps. You can combine the two to make it more suited to your needs: If each panel, +{lllll]-, produces 1v and 1amp then this panel produces 5v and 4amps
solarpanel.jpg
ahh ok thanks for the reply. now i get it.
Angus066 years ago
Yeah going along with what blindsided said, how is it that you wired those all in series and managed a whopping 1.85A out of that?
mattfelice (author)  Angus065 years ago
to gain the amperage you want just wire a few in parallel to make a "single cell, then continue the series. You can see examples of this on my panel
bomberss275 years ago
What are the dimensions of the entire solar panel? Also, how do you attach this to a charge controller or alligator clips which I could use to attach to a battery?
mattfelice (author)  bomberss275 years ago
its about 4' long by 15" wide
Jalloy5 years ago
(removed by author or community request)
mattfelice (author)  Jalloy5 years ago
please do
I am looking at running a 1,000 watt heater. How many watts will this operate?
A kilowatt solar array would require (approximately) 100 square feet of solid collectors. It would only deliver its kilowatt when the unimpeded sun was shining directly straight on to the array. I'm guessing the pictured array delivers 10-15 Watts.
mattfelice (author)  geetz5 years ago
19v 1.85 amps 35 watts in partial sun
jerber265 years ago
hi, can you connect those broken pieces together so that it will look like one whole solar panel?
mattfelice (author)  jerber265 years ago
you could but it would be realy hard
I am new to this stuff. so I'm not being sceptical, but I am wondering how you use this if one does not have an inverter.
I think many of the 15.4 inch notebooks use 19 or 20 V charger. So it could be probably used to charge/power one of those. I would recommend some voltage stabilisation.
Yes, this is the voltage that a 15.4 inch notebook would use normally, but you have to remember the current on the chargers as well. Most of them are in the excess of over 65watts. This solar panel would only be able to produce around a 10 to 12 watt max power. So yes it could probably charge a laptop but after a day or so of direct sunlight. It could never power a laptop unless it is big enough for a 65 watt which would be a very big solar panel.
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