Introduction: Octanis 1: How to Make Solar Panels

Octanis 1 will fly to Antarctica and land a satellite controlled rover. To do this, it needs lots of power and it will get it from the sun! Here's a guide on how to make Octanis' solar panels.

Find out more about the rover mission: http://octanis.org/

Step 1: Cut Your Cells

Cutting solar cells is the trickiest bit and this step depends on the type of solar cell and cutting device you use.

We used Sunpower C50 cells, that can be cut with a diamond glass cutter. It's enough to score the cell with precise force and then snap it carefully, hoping it will snap along the cut line. The yield for this is about 50%, so make sure you order enough cells!

Step 2: Clean Them

Use a sonicator bath to clean the cells. Make sure they don't overlap or touch each other as this would produce nasty stains.

Step 3: Prepare the Solar Panel Foundation

We will use adhesive foil as a layout guide and an easy way to keep the cells together when flipping them around after soldering.

Cut the adhesive foil to size (Octanis 1 has a panel size of 30cm x 30cm). Peel off the adhesive foil and set it aside. Place the non-adhesive side on a flat surface. Spray the clean solar cells with distilled water to get rid of dust.

Step 4: Layout & Solder the Cells

While the cells are still wet, place them on the non-adhesive side. Make sure you align them correctly (pay attention to the polarity).

Then solder them together using solar tabbing (get it on eBay). Octanis 1 uses a 7s2p (7 series, 2 parallel) configuration. Soldering is straightforward, use solder tin if necessary. Solder as you would solder a PCB.

Make sure you make the tabbing that goes out (where you will connect your load) is long enough.

Step 5: Prepare for Epoxy Pouring

When you're done with soldering, carefully stick the adhesive on to the solar cells. It should be sticking on the back side of the cells!

Turn over the panel and peel off the non-adhesive side.

Tape it onto a flat surface, make sure the tape is very strong. The epoxy has the potential to unstick the tape if it goes underneath it.

Step 6: Make a Border Out of Tape

... so the epoxy doesn't flow out. Again, this needs to stick well!

Step 7: Pour the Epoxy Resin

We used 10:6 two-part resin from OBI. For a panel size of 30x30cm we used 90ml of resin (A: 56ml, B: 34ml)

Step 8: Let the Resin Cure.

For faster curing (less than 5 days), leave it under a UV lamp.

Comments

author
nickton (author)2015-07-24

what is a sonicator bath?

author
fety (author)nickton2016-06-01

aka ultrasonic jewelry cleaner.

author
octanisorg (author)nickton2015-08-10

https://en.wikipedia.org/wiki/Sonication

author
octanisorg (author)2015-10-26

be sure to check out our new rover page. we'll be adding more info soon:

http://octanis.org/rover/

author
�L (author)2015-09-02

is there a materials list, like where to buy the stuff?

author
astrong0 (author)2015-07-24

Interesting project. What is the scope of the mission? Is it simply because you can or is this going to lead up to a more invested project? Perhaps testing certain novel devices in extreme temperatures?

author
octanisorg (author)astrong02015-08-10

we like to push the limits of what's possible using the open source and maker approach. check out our wiki for more info http://octanis.org/wiki/

author
slickdog (author)2015-07-24

In the textfor step 3 you state to place the foil non-adhisive side on a flat surface, then in step 4 you say to place the cells on the non-adhesive side. How do you do this when the non-adhesive sie is facing down, or is there an error in the text? Later on in step 5 the foil is stuck to to the panels and the non adhesive side taken off. This I find cinfusing are you using two seperate shgets of adhesive foil or is it in three layers with two non adhesive an one adhesive?

author
octanisorg (author)slickdog2015-08-10

the foil is this:

http://i01.i.aliimg.com/photo/v0/1659147627/plasti...

you cut it, then you peel off the white paper. align the cells on it (yes, blue face down). solder. place adhesive foil on top.

author
rafi_rfiq (author)2015-07-25

more informetion abuots cells. I meen how to make one by my sellf

author
octanisorg (author)rafi_rfiq2015-08-10

if you really want to make the individual cells (not the panels!) yourself, try

http://www.wikihow.com/Make-Solar-Cells

author
cavi21 (author)2015-07-26

Kinda OT, but what are your concerns about the weight of the Octanis and the winds in Antartica? Also are you planning to retrieve this thing after all the studies that you are planning to make?

Also thanks to share this!

author
octanisorg (author)cavi212015-08-10

the rover will be retrieved at some point, as abandoning it would not only be sad but would go against the antarctic treaty. our weight limit is 2.5kg.

for the locations we're currently looking at winds are not too much of an issue. if we do get blown over, our wheel struts can put us back into position and we shouldn't take much damage. summer vs winter weather makes a difference.

author
nwonharp (author)2015-07-28

In step 4 you say " use solder tin if necessary " What do you mean ? are you talking about using flux ? or " pre-tinning " the connectors before soldering ? Or maybe you keep your solder in a " tin can " ( LOL )

Cheers , take care , and have a good day !!

author
octanisorg (author)nwonharp2015-08-10

solder as you would solder any wire (https://www.instructables.com/id/Soldering-101%3A-Lesson-1%3A-Tin-the-Tip/). make sure you dont short out the traces.

author
g1ra (author)2015-07-31

I plan to make solar panel for my robot.

Please can you tell me what is the weight of one solar cell of this type? (only the bare solar cell without cover or soldering )

Where did you bought this solar cells?

author
octanisorg (author)g1ra2015-08-10

probably a couple of grams, the datasheet doesn't specify. you can get search for them on ebay.

author
freeyourmindok. (author)2015-07-26

Where do I buy the cells

author
WilliamL14 (author)2015-07-24

I really like this project but I seem to have missed some basic information. (Maybe you provided it and i just did not see it?) For starters, it's not clear to me why you cut the cells in that particular shape.

author

The uncut Sun Power cell has those rounded corners. So they cut the cell into 3 pieces. The leftover 3rd piece is used for a different project, presumably. They used all end pieces and that's the shape you get. Look like boats.

author
aashik1 (author)2015-07-23

what is it's total voltage?

author
octanisorg (author)aashik12015-07-23

3.5V

author
aashik1 (author)octanisorg2015-07-23

thanks

author
southdenver (author)2015-07-23

Why do you need to cut the cells, with a 50% discard rate seem like an expensive way to get smaller cells?

author
octanisorg (author)southdenver2015-07-23

Each cell has a nominal voltage of 0.5V. Our rover requires 3.5V. This would need 7 cells. We could skip cutting, but we would end up with a meter long cell.

When you cut a cell, the nominal voltage stays the same for each cut piece. That way you can get the voltage you want with a smaller surface area. If you don't care about the size, don't cut the cells.

author
244 Jake (author)octanisorg2015-07-23

1). True, the voltage would be the same, BUT the amps, the power, Watts, is reduced.
2). Hard to believe The solar panels shown, are powering the wheel motors, too small.
3). Normally the panel feed the battery charger in remote region. Battery feed the electronics.
4). Voltage controllers are so cheap, and reliable. In solar power the panel voltage vares widely during the day light cycle. Regulate down, to safely charge the batteries.
5). You are only cutting off the two corners of the cell, you have not change the height or the length of the cell package.

I have solar powered, animated yard toys and a 7.4 KW, On-Grid power system on my home in Baton Rouge. Have used solar panels to power remote cameras for long term, over two years, reporting of construction progress in remote areas.

I think there needs to be a meeting where system design is discussed across all design groups.

Big Jake

author
WoLf2Tails (author)2015-07-23

Im sorry if i just missed it but what was you cost for this project.

author
octanisorg (author)WoLf2Tails2015-07-23

a single panel costs just about 30€ if you can find cheap cells and resin

author
Locobox (author)2015-07-23

Is the sonic bath really necesary? I understand cells must be clean before aplication but is that level of sonic cleaning necesary?

author
octanisorg (author)Locobox2015-07-23

You can get away with spraying it with distilled water. They usually come clean enough for most DIY purposes.

author
wikkit (author)2015-07-23

Why are the cells cut?

author
octanisorg (author)wikkit2015-07-23

To get the total voltage to 3.5V on a small area.

author
treymartin82 (author)2015-07-23

Would this also work in say South Carolina, USA?

author
octanisorg (author)treymartin822015-07-23

Anywhere the sun shines!

author
jtechian (author)2015-07-23

Could you tell us where you bought the cells? Also is resin the better over silicone encapsulate. As I understood epoxy would form stress cracks in the cells after some time of heat expansion and contraction. Thanks.

author
octanisorg (author)jtechian2015-07-23

Nope, the resin is worse in many ways, it was just available to us then and there. We will probably uses Sylgard 184 for our next panels.

These cells here are factory blemish (but work perfectly fine!) and you can find them on ebay.

author
Odie Sr.O (author)2015-07-23

OK Where do you get the resin??

author
octanisorg (author)Odie Sr.O2015-07-23

We used a resin that we already had in the lab. It isn't made for this purpose but it works well. Usually you'll be able to find it at any hobby shop. To get better results, you can use "proper" encapsulation silicone like Sylgard 184. It's easy to find on ebay:

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR4.TRC2.A0.H0.Xsylgar.TRS0&_nkw=sylgard&_sacat=0

author
chipkona (author)2015-07-23

You could get a bit more power out if you degassed the epoxy with a vacuum.

Put the cup into one of the vacuum containers that comes with a food vacuum.

author
octanisorg (author)chipkona2015-07-23

Never thought of using a food vacuum sealer to degas. Great idea!

author
gabels (author)2015-07-23

What type of epoxy did you use? Common epoxy found in hobby-shops I think it's not UV resistantand it will became yellow over time

author
octanisorg (author)gabels2015-07-23

This one: http://www.obi.de/decom/product/Presto_Epoxyharz_...

In fact, yes it does get yellow and you shouldn't use this if you're looking to get the best performance. For our prototypes, we just want it to keep things together and since it's easily accessible to us, we use it.

author
lzalcik (author)2015-07-23

Wow! This is rocket science to me.

author
jsierra8 (author)2015-07-23

Really cool!! I love it.
Thanks for share!!!

author
graefawks (author)2015-07-22

I've been looking for a reason to use my Sonicator bath for ages..

author
tomatoskins (author)2015-07-21

This is cool! Whats the power output on it?

author
octanisorg (author)tomatoskins2015-07-21

It should give around 8-12W @ 3.5V, though I haven't measured yet. Here's the cells datasheet: http://www.akumulator.si/images/products/Soncne_celice_Sunpower.pdf

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Bio: A rover mission to Antarctica • Octanis is an association at EPFL pushing students to go beyond just solving exercise series.
More by octanisorg:Octanis 1: How to make ParachutesOctanis 1: How to Make Solar Panels
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