Build a 60 Watt Solar Panel

Several years ago I bought some remote property in Arizona. I am an astronomer and wanted a place to practice my hobby far away from the terrible light pollution found near cities of any real size. I found a great piece of property. The problem is, it's so remote that there is no electric service available. That's not really a problem. No electricity equals no light pollution. However, it would be nice to have at least a little electricity, since so much of life in the 21st century is dependent on it.

I built a wind turbine to provide some power on the remote property (will be another instructable in the future). It works great, when the wind blows. However, I wanted more power, and more dependable power. The wind seems to blow all the time on my property, except when I really need it too. I do get well over 300 sunny days a year on the property though, so solar power seems like the obvious choice to supplement the wind turbine. Solar panels are very expensive though. So I decided to try my hand at building my own. I used common tools and inexpensive and easy to acquire materials to build a solar panel that rivals commercial panels in power production, but completely blows them away in price. Read on for step by step instructions on how I did it.

You can learn more about this project and my other alternative energy projects, including my home-built 15 Watt solar panel, my home-made wind turbine, and my biomass gasifier on my web site.

Step 1 Buy some solar cells

I bought a couple of bricks of 3 X 6 mono-crystalline solar cells. It takes a total of 36 of these type solar cells wired in series to make a panel. Each cell produces about 1/2 Volt. 36 in series would give about 18 volts which would be good for charging 12 volt batteries. (Yes, you really need that high a Voltage to effectively charge 12 Volt batteries) This type of solar cell is as thin as paper and as brittle and fragile as glass. They are very easily damaged. The Ebay seller of these solar cells dips stacks of 18 in wax to stabilize them and make it easier to ship them without damaging them. The wax is quite a pain to remove though. If you can, find cells for sale that aren't dipped in wax. Keep in mind though that they may suffer some more damage in shipping. Notice that these cells have metal tabs on them. You want cells with tabs on them. You are already going to have to do a lot of soldering to build a panel from tabbed solar cells. If you buy cells without tabs, it will at least double the amount of soldering you have to do. So pay extra for tabbed cells.

I also bought a couple of lots of cells that weren't dipped in wax from another Ebay seller. These cells came packed in a plastic box. They rattled around in the box and got a little chipped up on the edges and corners. Minor chips don't really matter too much. They won't reduce the cell's output enough to worry about. These are all blemished and factory seconds anyway. The main reason solar cells get rejected is for chips. So what's another chip or two? All together I bought enough cells to make 2 panels. I knew I'd probably break or otherwise ruin at least a few during construction, so I bought extras.

Comments

[Nick Dolan]

And this is just the same copper wire from earlier?

[timmi]

Hello, could you possibly expand a little bit more on how you joined the strings of cells. Thanks

[Nick Dolan]

I'm having problems with this as well.

[rlaws]

Hi, Do you ever wished to have your own diy solar panels ?
It would take a long time to pay back to it around 8-10 years
But i know a website which tell the method to build your own solar panel
Just in 1 - 2 years.
Open Google and Search For "top diy solar panels"
See the first result.
Note: ignore the adds.

[working_it]

You need to use a low iron glass.
Plastic of any kind will fade in time.
You will also need to pot the solar cells in a special silicone that
is way more translucent then regular silicone.
Otherwise the light is really not getting in.
If your solar panel gets way hot, you will need to spray the underside
to get the wattage back up...heat kills the efficiency of the cells.

[tinker234]

could i harvest solar panels from garden stakes and solar toys

[blueline23]

This is a great project but how much money you need to build such a solar panel? Here is a short video where you can see how to tab solar cells for building such a panel.

[graphixv]

New factory 100 watt Solar panels are currently available in the $200-$250 range. I wouldn't go the DYI route unless you are planning to do an assembly line quantity of panels.

The cost to self-make a 100 watt panel is not that much different than buying a panel if you build it correctly. You also have the possibility of running into bad cells, user error and poor materials.

I would only go the DYI route if you’re building a huge system like 1000 watts. You could save 50% over factory panels building a lot of them, then again you may get poor panels. Check Ebay and Amazon for new panels. And remember, don’t buy small panels <50 watts, the cost per watt goes way up due to labor and other materials which are involved in making a panel of any size.

[mdavis19]

The situation was different 3 1/2 years ago when I originally posted this instructable. Anyway, there will always be people who prefer to roll their own, no matter how low the price of commercially made units go. If you aren't a maker, you wouldn't understand.

[graphixv]

I agree. I was just making sure people were updated. I also bought some cells to make a panel not knowing at the time what the real cost would be and ended up buying a panel instead. If someone goes the DYI route, they may want to spend another $2 and install some dypass diods to make their panel shade resistant.

[nepwk]

Excellent project. HOWEVER, if you try to build this keep in mind that you will NOT get 60 watts out of it (as claimed by the author) using the cells that this author used.

The author claims it produces 18.88 volts OPEN CIRCUIT with NO LOAD. No problem there. This is pretty much typical for 36 cells in series.

The author claims it produces 3.05 amp SHORT CIRCUIT CURRENT. Again, no problem as this is typical of this size solar cell.

And it's true that volts x amps = watts.

However, you can not multiply 3.05 amps short circuit current by 18.88 open circuit volts and come up with ~60 watts (57.584 watts to be exact).

Why?

When the solar panel is short circuited you get 3.05 amps at ZERO volts. 3.05 x 0 = ZERO WATTS.

When the solar panel is open circuit you get 18.88 volts at ZERO amps. 18.88 volts x 0 amps = ZERO WATTS.

What you need to look at is the IV curve (I=current in amps and V=voltage in volts) for the solar cell being used. When the solar panel is producing the maximum amount of power that it can produce the voltage will ALWAYS be LESS than the open circuit voltage and the current will ALWAYS be LESS than the short circuit current. Do NOT expect to see anywhere near the 60 watts claimed for this solar panel if you decide to build it. Depending on the exact solar cells that you get, expect to see more like 30 to 40 watts under load and you will not be disappointed.

This author makes the same error in his "How I built a folding 15 Watt Solar Panel" instructable where he also multiplies SHORT CIRCUIT CURRENT by OPEN CIRCUIT voltage and comes up with 15 watts for 40 cells (or 2.67 watts per cell) which is impossible considering that those cells are only capable of producing ~0.25 watt per cell under IDEAL conditions and more like 0.15 watts per cell under typical conditions.

Again, NICE PROJECT but the author REALLY needs to correct the mis-information he is posting in these instructables and on his website.

[graphixv]

Good comments. There are way too many Pie-In-the-sky claims made by people who make panels. And, way too many claims you can save 75% off factory panels by making them yourself. I blame all this on the second hand, B solar cell peddlers out there. They try to convince people they can make a solar panel for pennies on the dollar by purchasing their junk cells. Only after purchasing, the buyer finds out that the panel cost is going to be much higher unless big corners are cut.

[jcvillar]

Nice construction, but I worry that you are not using an encapsulant, such as SylGard, to prevent degradation of the cells.

[RisingSun]

If I was your panel I would be afraid of a critter jumping or climbing on me, although I don't know what your place is like. Really cool instructable btw

[gneal]

Thank you so much for this instructable. I actually built a solar panel using your instructions and it works great. I hooked it up to my DIY electric fence and it works perfectly. My dog knows what its boundaries are now.

[Valence_4]

Another important thing to greatly improve the panel's efficiency: Solar cells do provide a 0.45volt FORWARD voltage when lit by sunshine but will act as a REVERSE biased diode if unlit. So if a leaf falls on one cell of your panel, the overall efficiency will be HIGHLY reduced by the unlit cell that will absorb a high reverse voltage. This will not only highly reduce the panel's efficiency but may also damage the unlit cell if the panel is loaded. To prevent this, i strongly suggest you to buy 3 ampere shottky diodes (1N5820 for example), one per cell, and solder them un PARALLEL with each cell. The polarity is important. For that, use one cell, put it under sunlight and using a voltmeter, test which side is positive and which is negative. If i remember well, the top side is negative. Then, solder long bare wire (AWG24 will do the job) to each end of the diode and then, solder the bare wires onto BOTH tabs of the solar cells with the CATHODE (banded) side on the POSITIVE side of the cell and the ANODE (no band) side on the NEGATIVE side of the cell. On normal use, the diodes will be REVERSE biased and will have NO EFFECT on the overall panel's efficiency. But in one or a few cells are shaded either by a leaf, a bird or a tree's shade, thee diodes will start to conduct as the solar cell is reversed biased. This way, the whole panel will continue to generate power and the shaded cell(s) will be protected by the diode that will limit the cell's reverse voltage to less than 1/2 volt. I suggest Shottky diodes rather than ordinary 1N5401because of their lower forward voltage (typ. 475mV) compared to classic PN junction diodes (1 volt Vf).

[Itchyzombie]

Or you can Buy more solar sells to provide power for fans to blow them off BTW he said his place is windy all the time.

[bhouse2]

so basically you're telling me that if a large leaf shades 1 solar cell in a series of 36 the voltage drops to 0 becauce it is essentially breaking the circuit that would be expensive to buy 1 diode per cell how come no one else mentions this

[speedstix]

I highly recommend doing this as well. All those cells in series are all affected if one of them is unlit. The current drops to the one cell that is unlit (0 amps).

[raja681]

what is a good price for 120 of these

[ezrablu]

AWESOME instructible...THANK YOU for sharing this with the world who would otherwise be prisoner to purchasing panels for big bucks or not being able to afford them all.

[nitepagn]

My thought exactly. I want to build a solar system, but can't afford the high cost of panels.

[sspence]

I thing something less susceptible to moisture (the peg board we get is really pressed paper layers and delaminates easily) would last longer. Just a thought.

[ElectricMan1]

What do you think is better than peg board?

[Morganbarker]

white melamine. which is similar to pegboard, but it seems to have more binder material pressed into it. It costs a little less than pegboard (if I recall) and is in the same aisle of your home improvement store.

[sspence]

 Marine plywood maybe? Or a sheet of plexiglass (expensive but durable).

[warren4321]

For the latest update on DIY solar cells you can refer to http://www.buysolarpanelweb.com

[king7070]

i want to buy 3 X 6 mono-crystalline solar cells !!! please tell me the web site where i can buy these cells . i am waiting for your's reply

[airsofter1]

Ebay, you also could read the instructable to find out...

[ourmoneypit]

I save those little packets of silica that come packed with everything these days. Could you tuck one of those into each unit to address the moisture issue?

Good 'ible and all the comments/discussion has been helpful, too.

[edraq58]

Can I put the diode to the negative side of the panel? If not, what is the effect if diode install to the negative?

[kktwags]

I made 4 60 watt solar panels , they work great for the most part , we installed them on our awning with 2x4's unerneath for air to get through however we are having major moisture issues.  when we built the first two we thought it was because we used to much silicone and didn't seal up the sides good enough but we just built two more with alot less silicone and we sealed the sides with aluminum tape however there is still alot of moisture in the panels.  It always starts with a fog and then turns into alot of water droplets.   Do you or anyonelse have any suggestions on how to fix this or why this is happening. We can't haven't been able to come up with any other reason.

[dfwsupergeek]

If you can get ahold of a vaccuum pump, such as the kind used in the refrigeration/air conditioning field, you could conceivably pull a vaccuum on the almost-sealed panel, then seal it... Now that I think about it, I should write an instructable on how to do this! Anyhow, you're getting condensation because of the air trapped inside, and as long as there is any air with any moisture trapped in it, you'll always get that fog. Just a last minute thought- what if you didn't completely seal the panel, allowing someplace for the moisture to go? It would simply evaporate, and you'd have no more fog problems.

[notmyfault]

I had this kind of issue when the first dual pane thermal windows came out. It has to do with how much humidity was in the air when the windows were sealed.  A couple of thoughts on how to solve..... Get some decissent packs used to keep moisture out of cameras ect... put them inside before sealing.... or get your tires filled with nitrogen ( some tire stores fill with nitrogen now ) and use the nitrogen to displace the air in the panels... I hope this helps.....NMF

[mnc_co_uk]

just to clarify, wattage(otherwise known as power) is volts * amps. Connecting panels in parallel or series will both increase wattage. However it does give you the abilty to adjust your current / voltage rating. Say you had 2 equal panels they both give 12volts 5amps. connected in series would give you a overall solar panel of 24volts 5amps. connected in parallel they would give 12volts 10amps. Combined in either combination would give power of 120watts.

[Big Black Dog]

@LVGene: Harbor Freight's panels are 4-5 times the price ($380 for 50w, $500 for 75w), and if you don't like to "tinker", why are you perusing a do-it-yourself website?

[LVGene]

No. If you are buying solar panels.. ONLY. Then you need to make further decisions. I was and still am talking about the Harbor Freight 45 watt KIT. Not high wattage panels. If I take your word for it. Your "Panel" costs $100 all in. The result is totally sub standard in every possible way. And (as you continue to ignore) Harbor Freight has sales all the time. So to say they are 4 - 5 times the price is incorrect. If the buyer takes advantage of a sale.. (every week they have a sale) the builder will get a solar panel that is warrantied and will most likely last for 70 plus years. A wood housing can NOT stand up to sustained heat, UV, and weather. But the Harbor Freight design is built using aluminum not wood. It will last the "Tinkerer" a lifetime. There is a reason why they sell solar cell 2nds. Because they most likely will not last. I'm sorry if this comes off harsh. But I'm not the one creating an Un-Supported "How To" web pages that have undisclosed affiliate links in them. IMHO it is 100% Unethical to do what you are doing. I also believe that an Honest Builder (or Tinkerer) will end up spending a whole lot more on his duplication of your simple panel.. and kicking YOU back his/her hard earned $$$. If you disclosed that you earn money if the builder clicks on your affilaite links.. Like for Ebay cells or Solar Books. Yes that would be ethical. Also.. since you earn money off of the "Builders"... You should offer support. Reading your page.. you do not. I just joined Instructible's a few days ago. I'll post my own Instructible in a while. But I'll also do it ethically. Not using Instructible as a way to pimp my kits and earn extra dough.

[hurricanejohn]

I don't usually get involved in these flame wars but in this case I'll make a exception. first and foremost this guy is amateur astronomer  that built himself a solar panel for his hobby in the desert. Not a lot of rain there. Yes there are some flash floods but as a rule not much rain so the wood aspect of his construction shouldn't be a issue and he does have ventilation in it. He also covered it in metal tape (used a lot on the outside of commercial airliners)   later on so there should be no moisture or very little moisture getting into it. He also painted the wood. now I don't know what type of paint he used but I'm pretty sure it was a good outdoor outdoor paint (a person could use marine paint if they wanted not cheap but no moisture issues). as for him buying "seconds" who cares? he took into account they weren't perfect and bought extras it's still cheaper. So what if he has affiliate links on his website? Most anybody who uses the Internet knows that ad links earn the website owner a little money and he puts it to running his website so that he can provide the public at large FREE information. So don't slam a guy for showing people how to do something. Remember he didn't have to tell anyone how to do it. I personally think its awesome.

[lloydrmc]

How's the view from your high horse?  This site is about building stuff.  Who said it had to be better in ANY way than something available commercially?

For example, a modern automobile is superior in almost every way, to a street rod (except perhaps power/weight and general fun), yet the latter can cost many more times than the former.  Still, people build street rods, some of which wouldn't be caught dead in a modern car.  Go figure.

[blizzarddemon]

Seems rather contradictory that you should flame the action of this how this man chooses to give credit where it's due, when your actions of obvious advertisement (Seriously, you mentioned Harbor Freight with a consistency of a televangelist <.<) ends up pretty much nullifying any argument you can make on that matter.

If he misses a deal, big deal, it's not the end of the world. Besides the shipping end of things tends to be another hinderance most people don't take into consideration when people talk about cost. With his remote location I'm sure shipping must come at a heavy cost in either case.