Intro: DIY Long Lasting 36 Cell Solar Panel (60 Watts)
I became interested in solar panels and making my own for my garage so that I could do more household projects. I don't have an electrical degree but with the vast amount of knowledge, tips and tricks regarding building solar panels on the interweb, I wanted to consolidate and share my project with those who are also interested in making a solar panel out of quality materials that will last for more than 15 years.
Step 1: Tools
Most of the tools needed are for constructing the aluminum frame. I decided to make my own frame just to save a few bucks. My plan was to make a panel to closely mimic one you could purchase fully constructed from a retailer but to cut cost by doing it myself from the ground up. The frame is the main piece where doing it yourself will save your wallet. Well, that and obviously wiring the cells yourself, too.
Box Cutter or Scissors
Metal Working Drill Bits (makes drilling the aluminum a little easier)
Clamps, Makes using the mitre box easier
Sockets (I list these only to be used as weights to weigh down the panels when wiring these in series. This will make more sense later.)
Step 2: Materials
The materials come from a few sources but are mostly the local hardware store and eBay.
(1 Pack) 9mm X 12 mm Corner brace
(4) 1/16" X 3/4" - 36" Aluminum angle
100% Silicon Caulk
(40 Feet, Minimum) Tabbing Wire
(20 Inches, Minimum) Bus Wire
Flux Pen, Kester #186
Schotky Diode, 6 Amp Axial Type, The last four items came as a set purchase from mlsolar on eBay.
(36) 3" X 6" Solar Panels, I bought from mlsolar on eBay
(1) Solar Tite 386S Silicone Elastomer Solar Cell Encapsulant
Several Feet of 10 AWG wire
Weatherproof 10 AWG connector, I got mine from allelectronics.com
(6) Wing Wire Nuts
(1) 1/4" thick 26 1/2" x 32 1/4"Tempered Glass (I got mine at www.affordablesolarframes.com)
Note: www.affordablesolarframes.com has a bundle where you get the glass and the frame for $112 or you could just get the glass like I did for $75 and make your own aluminum frame for much less than $37. It is up to you if you want to buy the frame with it, granted, it is way better quality than the one I will make here and comes with brackets you can attach to the sides to help mount the finished panel.
You will eventually need to buy a charge controller, Battery (preferably a sealed lead acid type, or deep cycle for more heavy duty power usage), power inverter and if you are Really trying to supplement your electric bill a Grid tie inverter.
Step 3: Solar Power Potential, Overview, and Some Electrical Basics
The Basic Set Up is that the solar panel takes photons from the sun to excite the electrons in the silicon panels to create a potential needed to create electricity. The wired up solar panel allows electricity to flow through the charge controller to regulate the amount of current going to a battery so as not to over charge and potentially ruin the single battery or a battery bank. The battery can be hooked up to directly to power Direct Current (DC) loads only. If a power inverter is connected to the terminals of the battery, the outlet(s) could be used to power Alternating Current (AC) loads.
Most power inverters are called Modified Sine Wave Power Inverters, however there are more expensive Pure Sine Wave Inverters. Pure sine wave inverters will be more accomodating for electronic use such as televisions, laptops and gaming systems. These will make the picture more crisp like we are accustomed to and will not be "choppy." If a Grid Tie Inverter is connected, then the opposite end could be plugged into any outlet of your house and the electricity generated by the solar panel will directly supplement your electricity bill. Some solar arrays in the Kilowatt ranges could even drive your electricity meter backwards and feed excess energy back into the grid. (!!! Check with local and state regulations as well as your electric company regarding grid tie inverters for legality purposes!!!)
Wires: Red = Positive (+), Black = Negative (-)
When it comes to wiring electrical components, there is a series and parallel wiring. Wiring in Parallel means the positive wire is connected to another positive wire and the associate negative wire is connected to the other negative wire. Wiring is Series means the positive wire is connected to the negative wire and the associated negative wire is connected to the other positive wire.
Wiring a Battery in series with a second battery will double the output Voltage. Therefore, if you had two 12V, 10 Amp hour Deep Cycle Batteries wired in series, your outcome would be a 24V, 10 amp hour battery bank effectively.
Wiring a Battery in parallel with a seconc battery will double the amp hour usage, Therefore, if you had two 12V, 10 amp hour deep cycle batteries wired in parallel, your outcome would be a 12V, 20 amp hour battery bank effectively.
Now you may be wondering what is the best wiring sceme for a battery bank. First let's do some math...I know! I know! Math!?! but bear with me, it won't be That bad :)
The battery that I use in this instructable is a 12Volt 10 AH (amp hour) battery. That means that, using the power equations for batteries: V*A=Watts, 12V * 10AH = 120 Watt hours. That means that if I had a 60 Watt bulb being powered from the battery directly, 120 WH / 60 Watts = 2 hours worth of use. By dividing Watt Hours by the wattage of the load being utilized, the watt unit of the equation cancels out and leave the amount of time the load can theoretically be used. I am sure there is some sort of tolerance like +/- 10% where you might be able to pulle a few more minutes after the two hour mark or on the flip side, less than two hours
If I wanted to use that 60 Watt load for more time, I could wire another battery in parallel to double the amount of amp hours to 20 AH and therefore have a total of 240 Watt hours. I could then use the 60 watt load for 4 hours now, as opposed to the two hours with just one battery! If you had a DC load that didn't utilize 12 volts but 24 volts instead, you would need to wire the batteries in series so that the output voltage would be 24V.
One final note, If you have a panel wired to some amperage, say 5 Amps, and you have a 10 Amp Hour battery that was dead, it would take about 2 hours to fully charge the battery (provided you have a higher voltage panel compared to the battery, i.e. an 18V panel for a 12V battery like I do in this instructable). I have seen deep cycle batteries in the range of 60AH and, again for example, with the same 5A panel, it would take 12 hours to fully charge the battery.
One final final note on the use of Deep Cycle batteries, these are specifically made to be fully discharged and subsequently fully charged over and over, hence the name. So if you plan on fully discharging the battery over and over or simply don't have the drive to check the battery's life every second you are using it, go with deep cycle batteries.
And that's that! Not too bad, yeah?!
Step 4: The Frame
I purchased four pieces of the aluminum angle described in the "Materials" step and these needed to be measured and cut. These pieces come 3 feet long and I needed to mimic the dimensions as described on affordablesolarframes.com. Therefore, 2 of the 4 pieces were cut to 27 inches and the remaining two were cut to 33 inches. If you look at the aforementioned website, I says 32 3/4" but I wanted to leave a little room to hide the wires later.
When I made the cuts, I did so with my mitre box and hacksaw at a 45 degree cut. MAKE SURE you are using the right 45 degree angle because I almost made a wrong one where the inner angle would have been facing outside and would make no sense. I had to use a piece of spare wood to act as a spacer to get the cuts to go all the way through because my mitre box is deep for my hacksaw. However, if you have a bandsaw...lucky you because you could get in done in 5 minutes unlike me who spent hours yelling at my hacksaw in a fit of fatigue.
Next, use a file or grit paper to smooth all the burrs on the edges. I used a marker to know where to drill holes for the corner bracers and drilled them out. Secure the bracers with the screws and due to my hacksaw work, the frame was slightly flimsy but still rigid enough to get the job done.
One final tip is to drill the holes closer to the top edge of the frame and not "IN" the angle. You need room for the tempered glass to fit and if you put the bracers right smack dab in the angle the tolerance may be too too snug for comfort. Drill two holes in the top of the frame for the output wires to come out of for later, as well.
Step 5: Tabbing the Cells
This panel will use 4 strings of 9 cells making a total of (4*9) 36 cells. You could get them on eBay "pretabbed" for a little extra moneys but from what I have seen the tabbing wire barely sticks out over the top of the individual cell and so you'd have to either re-solder it or solder more tabbing wire to the nub and that is just as much of a hassle to deal with.
These cells are 0.5V, ~3.5A each and wired in series will...What?? That's Right! make the finished panel 18V, and still ~3.5A! If you just had a panel that was right on 12V and were trying to charge a 12V battery, IT WON'T! You need that extra bump in voltage to keep that difference of potential to charge the battery.
In the materials section, the pic that shows all the tabbing wire in little strips needed to be manually cut myself. Tabbing wire usually comes in a spool and that is why I cut a piece of cardboard 3 inches in dimension. I know what you're thinking, " Why not just cut a 6 inch piece of cardboard since the stripes need to be 6 inches long?" Well I wanted to be sure the wire had a little over 6 inches from looping it around the cardboard because there needs to be a slight gap between cells.
Once you have 72 pieces of tabbing wire, you need to apply a little bit of flux from your flux pen to the two gray strips on the front of the solar cell and use your soldering iron to solder it down like in the first pic. Tabbing wire has solder on it so don't worry about applying more. You will know when the iron is hot enough because the tabbing wire will physically change a bit to fuse to the solar cell.
I tabbed the front of all 36 cells only. I wanted to do this first to test each individual cell against the sun to ensure they were not defective or I didn't overheat them while tabbing or some such fiasco. Testing voltage of the cells early and often prevent a huge headache...no...migraine, later on the in the wiring. The next step is soldering the tabbing wire on the fronts of the panels to the back of the next cell. This is the series wiring as seen in pic two.
Step 6: Solar Cell Wiring
Wiring the front of the cells to the back of the next cell is what ups the voltage of the completed panel. Pic one shows where to apply the flux, pic two and pic three show some techniques to steady your soldering. Thanks to Dan Rojas from YouTube's GreenPowerScience on the tape tip and Mark from affordablesolarframes.com for the pick (or screw driver) tip. These two tips makes things super easy and cheap. I have seen people use those "X" things for tile work to space out their cells but I think this a waste of valuable space and money.
When you have all 4 rows of 9 cells wired up, you will need some extra tabbing wire to go on the back of the butt end of the row. This is so we can bus the rows together. You will notice this on pic 4.
Step 7: The Glass
Let's take a break from those delicate cells shall we?!
I wanted to get the glass onto the frame and let it dry while bussing the rows of cells. All you need here is the silicone caulk and apply it to the inside of the frame. Apply it right down the middle to allow it to seep under the glass but not so much where it will "climb" the left wall of the angle or drip out in the front of the glass.
Let me just say that i went with this glass and aluminum combo because of the quality!!! (emphasis on Quality) You do NOT want to use plexiglass or wood or annealed glass for your frame. Plexiglass will scratch with branches and whatnot falling on it. And if you live in the dessert where the sun is plentiful, the dust will jack up the plastic. Annealed glass Will break if too much pressure is applied be it snow build up or other stuff falling on it. And a wood frame WILL warp and Will break your delicate solar cells. I want to reiterate that this solar panel is being made to last for 15 years or more (hopefully more :) )
Apply the silicone to the frame, put on the glass and press down to ensure good contact, let the silicone dry (overnight would definitely be best) and use spacers like spare pieces of wood to protect your floor, carpet or table. Whatever the frame is drying on. You don't want to pull up little pieces of carpet in your dried silicone.
Step 8: Bussing the Cells
The pic here shows what the final product regarding the cells will look like.
The idea here is Keeping the panel in series. (by now, you are probably like, "Geez, I get it already! Series, yeah.") I mentioned that you needed to tab the back of the butt end of the row of cells. This is because your cells are wired back to front, back to front going down the line. So we need to continue this by bussing the rows back to front.
I am heavily refering to my picture here. The bus bars are not soldered in place and are shown to give a roadmap on how to accomplish the series wiring. You will need to flip around two of the four rows and this is why you need to tab the backs of the cells. The bus bars are merely larger versions of their tabbing wire counterparts but I would suggest some additional solder just to ensure the junction between the bus and the tabbing wire.
Step 9: The (80%) Finished Product
This is where the hard work pays off!
Step 10: Output Wiring and Encapsulant Preparation
Now that the cells are done, we need to add the output wire. Since this is a 60W panel, I chose to use 10 gauge wire. Pretinning the wire just means you heat up the raw copper and add solder to it. This makes soldering the wire to the bus waaaaay easier. Just putting the raw copper to the bus and applying solder will take forever if at all to get it to stick. After it was soldered I added some Silicone for added reinforcement. Strapping Tape will help hold things in place and the sockets will weigh busses down while as well.
Prep for the resin by adding a border of silicone. This will keep the resin from flowing out to the edge of the glass and on the backs of the panel itself. EVERY DROP OF ENCAPSULANT COUNTS!
Step 11: Encapsulant
The Resin Encapsulant is a two part system that will harden once combined. You need every drop of resin for the amount that usually comes in the 16 oz. set like this. I used an extra butter knife for my stir stick. I have an extra square container in the pic because you really want to pour resin from the original container to the spare and back to the original a few times to ensure all the crevices get stirred up and get in full contact with the curing agent. If you choose to skip the pouring tip, you will more than likely have spots that will remain tacky for what seems like forever.
The silicone border will help keep the resin in place to get as much as you can on the back of the cells. Eventually the resin will seep into all the nooks and crannies. This is where that pastry brush in the pic comes in handy to spread it all around. You want a good even coat. It is good to have your panel sit in a cool place while it sets. This will take a while and that is good! You want a long set time so that the air bubbles will rise to the top and pop. Bubbles aren't a bad thing but it's best to avoid them. If your resin is taking a long time to set and still feels "sticky" you could set it by a window that gets a lot of sun light.
Use a good Solar! quality resin. Don't go out and get cheap epoxy because after a lot of exposure to direct sun light your panel Will yellow and this Will affect the efficiency of your panel over time. Like I mentioned before, I am building a panel that will last over a decade, not a couple summers!!
PS Don't put cardboard over the back of the panel to protect it while it is drying! It Will SAG, dry and stick to the resin and Will ruin the panel by cracking your cells.
Step 12: Finish Wiring and Enjoy Solar Energy
I used some wire wing nuts to complete the wiring from the panel to the weather proof connector. I got the weatherproof connector from allelectronics.com and it came as one piece and needed to cut it in half and wire it to the 10 AWG wire. Soldering it proved difficult mainly with tinning so as a temporary fix, this is why I use the wire wing nuts. Eventually I want to solder them together and protect it with shrink wrap and possibly more silicone.
The panel was then connected to the charge controller, the controller to the battery and then it commenced charging. Within little time, the battery when from an initial charge of 12.8 to 13.3V and stayed there. The charge controller is doing its job then!
And that is that. Solar energy with no CO2 or pollutants powering household devices. As mentioned before, the battery does DC loads and getting an inverter will convert the 12V DC to 120V AC to power electric devices that call for 120V. Getting more batteries wired tegether and fully charged will help with power outages and that way you won't have a noisy gas guzzling generator to worry about. Or you could build more panels and grid tie it directly to the house to supplement your bill (if your power co./state allows).
I hope this clears building your own high quality solar panel up. I just viewed a lot of videos, read a ton of articles and it paided off for me. Building this panel set me back about $150 but compared to buying a quality 60W panel at $250-ish, I'll take it. Building it was actually pretty fun, kept me busy and expanded my electrical know how. I hope this inspires you to build your own and save some money! Enjoy.