Step 11: Install the Blocking Diode

Each solar panel in a solar power system needs a blocking diode in series with it to prevent the panel from discharging your batteries at night or during cloudy weather. I used a Schottky diode with a 3.3 Amp current rating. Schottky diodes have a much lower forward voltage drop than ordinary rectifier diodes, so less power is wasted. Every Watt counts when you are off-grid. I got a package of 25 31DQ03 Schottky diodes on Ebay for only a few bucks. So I have enough left-overs for lots more solar panels

My original plan was to mount the diode inline with the positive wire outside the panel. After looking at the spec-sheet for the diode though, I decided to mount it inside since the forward voltage drop gets lower as the temperature rises. It will be warmer inside the panel and the diode will work more efficiently. More silicone caulk was used to anchor the diode and wires.
Jatiswar chakrzbortyn
<p>Im using http://inplix.com instructions to make it and I do it already :)</p>
<p>Today just looking ebay diy cell and diy panel cost about 100W 40-60&euro; and what more panel parts buy have cheapen nominal home need 1000W or 4000W but 1000W have under 1&euro;/W save about 1000W 400&euro; because prices have come ewery year down lot. before 1000W cost little up 1&euro;/W now about 40 cent/W nominal prize. ready to use panel cost about 2-6&euro;/W or more, what seller want lie and fool you :D better made diy panel and forget all fool seller.</p>
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<p>I know a solar panels seller website in my are www.electrical.bazaronweb.com but they are not selling solar cells , where to buy solar cells in lucknow, India any idea ? </p>
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<p>I made it but the cells easily crack and also it makes it a bit difficult. The heat inside the cabinet bends the cells and to prevent further damage I removed it from solar. How to prevent it. I am using acrylic sheet to make window.</p>
<p>Please help me. <br>1. where can i get this solar cells ?<br>2. What is the difference between mono crystalline, poly crystal and multi-crystalline?<br>3. How many pieces of solar cells are there in 1 kg f it?</p>
could i harvest solar panels from garden stakes and solar toys
<p>You *could*, but they won't be very powerful and you will need a very large quantity. Also, if they aren't all the same type, putting them in series will only give you as much current as the smallest one.</p>
<p>thank you for this very nice project...</p><p>I want to ask you if i want to buy the solar cell what must be its power?</p>
<p>I was looking for a higher capacity Solar System (400W or more). I found a really nice instructable. Heres a link<a href="https://www.instructables.com/id/Apartment-Solar-System/" rel="nofollow">https://www.instructables.com/id/Apartment-Solar-System/</a></p>
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.<br><br>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.<br><br>The author claims it produces 3.05 amp SHORT CIRCUIT CURRENT. Again, no problem as this is typical of this size solar cell.<br><br>And it's true that volts x amps = watts.<br><br>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).<br><br>Why?<br><br>When the solar panel is short circuited you get 3.05 amps at ZERO volts. 3.05 x 0 = ZERO WATTS.<br><br>When the solar panel is open circuit you get 18.88 volts at ZERO amps. 18.88 volts x 0 amps = ZERO WATTS.<br><br>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.<br><br>This author makes the same error in his &quot;How I built a folding 15 Watt Solar Panel&quot; 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.<br><br>Again, NICE PROJECT but the author REALLY needs to correct the mis-information he is posting in these instructables and on his website.
<p>you are absolutely incorrect. by ohms law itself. it takes one volt of pressure to push one current of power through one ohm of resistance. therefore 3.05 amps requires at least 3.05 volts. but the ultimate truth you are probably looking for is that direct current CANNOT, WILL NOT, and NEVER WILL BE measurable in watts. to this very day, and i fear, for quite some time the difference between AC and DC will be misunderstood by even PHD holding electrical engineers. i am currently part of a project to rectify the problem. but fighting academia is harder than one might think, unless you consider how many theses for doctorates that would be nullified are taken into account. good job on the instructable. and never trust a PHD. ;)</p>
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.
<p>This came up again in Instructables, I guess this video was made almost 4 years ago. Today you can find solar panels at less than $1 a watt, some as cheap as 60 cents a watt. cheaper than they can be made and they can live outside...</p>
So how many total diodes were used on this?
Hi there, <br> <br>I just wanted to say, I built 20 solar panels because of this instructable, so thank you. It helped me a great deal understand about solar power and saving real cash from buying from the electrical company. <br> <br>Currently on top of my house, there are over 20 panels I made by hand using local materials here in asia using your specs. I bought solar cells from ebay marked as B grade or A grade, almost exact replicas of the images on this instructable. It took over 2 years to complete them (at least for me). <br> <br>There are a few caveats I ran into while building the first panel, which I shortly learned then fixed on the 2nd panel. Then more problems happened on the 2nd panel until what I have is my 20th panel. <br> <br>1) Rain. It rains about 6 months of the year. I used silicon caulk bought from Home Depot., to seal the panels as per your instructions. However, water eventually made it through the wood, regardless how many layers of external paint I applied to each panel and upped the amount of silicon to seal. <br>To solve the problem now, and in the future, I read somewhere else that people bury there solar cells inside clear epoxy. That did the trick. I no longer had problems with water seeping in. However, it did dramatically increase the cost of making the panels. Resin or Epoxy is not cheap even in big quantities. <br> <br>2) Plexi-glass didnt cut it. It immediately warped the the shape and size and domed. I replaced the plexi-glass with standard window glass cut to size. <br>Due to the other 6 months, where it doesnt rain, nothing but pure hot sunlight. <br> <br>3) Amperage is dropping over time. My panels are giving me an open voltage between 18V and 21V. Under load, the voltage drops to around 13.7. (when everything is all connected) The amperage is dropping on some of the panels <br>The amperage varied when first built gave around 1.8 amps to 2.4 amps. <br>Now each panel 2 years later, dropped to 1.1 amps to 1.6 amps. <br>That's a pretty big drop in total amount of wattage. Its also a huge red flag to anyone building their own panels. <br> <br>4) Repair. If you ever need to repair the cells, you're going to need to open up the panel. For areas that doesnt have extreme weather, resin/epoxy is probably not necessary. But at first, one of the instructions was to glue <br>the solar cell to the wooden backing, so that it stays put. I'm sure this instructable, never thought about having to repair the panel itself. But gluing the cell to the wooden backing is an absolute no-no. Not only is it frustrating hard to remove, it is almost impossible ( at least in my own experience ) <br> <br>Anyways, thanks for the instructable. Im not sure if DIY is a good way to go now, now that I learned more about the process and building them. The factory stuff bought from the store is already pre-made for outdoor environments. The savings between a panel and building your own these <br>days is negigible. <br>
I have found that using a heat gun (very similar to a hair blower) in the low heat setting can do the trick of cleaning off the residual wax from the cells while athe same time using cotton cloth or paper towels to wick out the molten wax. <br>
Hello, could you possibly expand a little bit more on how you joined the strings of cells. Thanks
http://www.youtube.com/watch?v=5Zy3ELxwdtE <br> <br>this video goes into great detail
http://youtu.be/5Zy3ELxwdtE <br> <br>this video goes in depth with the whole process <br>
I'm having problems with this as well.
Exacty, still no lasting, affordable way to get electricity from the sun! When will this happen ? Not in our lifetime! So solly, cholly!
Could you show where you hooked up the tester to the wires? Did you just touch the electrode to each of the prongs on the plug?
And this is just the same copper wire from earlier?
You need to use a low iron glass.<br>Plastic of any kind will fade in time.<br>You will also need to pot the solar cells in a special silicone that<br>is way more translucent then regular silicone.<br>Otherwise the light is really not getting in.<br>If your solar panel gets way hot, you will need to spray the underside<br>to get the wattage back up...heat kills the efficiency of the cells.
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.<br><br>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.<br><br>I would only go the DYI route if you&rsquo;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&rsquo;t buy small panels &lt;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.
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.
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.
Nice construction, but I worry that you are not using an encapsulant, such as SylGard, to prevent degradation of the cells.
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
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 <a href="http://www.safetyelectricdogfence.com">DIY electric fence</a> and it works perfectly. My dog knows what its boundaries are now.
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).
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.
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
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).
what is a good price for 120 of these
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.
My thought exactly. I want to build a solar system, but can't afford the high cost of panels.
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.
What do you think is better than peg board?
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.
&nbsp;Marine plywood maybe? Or a sheet of plexiglass (expensive but durable).
For the latest update on DIY solar cells you can refer to http://www.buysolarpanelweb.com

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