Hi I’m Amy from the altE Store. I’m going to show you the difference between60 cell solar panels, and 72 cell solar panels. Other than the obvious difference of 12 solarcells, there are pros and cons to using each of them in different solar power systems. First a little background. Solar panels aremade from blocks of silicon ingots that are cut into square cells. Those are the squares that you see that makeup the solar panels. Each solar cell produces about a half a volt.
They then wire multiple cells in series, plusto minus, to make a solar panel. Wiring the cells in series increase the solarpanel voltage to a usable level. The more cells that are wired in series, thehigher the voltage. For example, if 36 cells are wired in series,you get an output of about 18 volts. Now, solar first got its start in the batterybased off grid world, where solar panels were built to charge a battery bank. The 36 cell solar panel that outputs 18V isperfect for charging a 12V battery bank, since you need a higher voltage to charge a battery.
So a 36 cell solar panel is called a 12V â€œnominalâ€�panel, as it is designed to charge a 12V battery. Likewise, a solar panel with twice as manycells, 72 cells, outputs about 36 volts, and it is great for charging a 24V battery bank. So it is called? You got it, a 24V nominalsolar panel. If you have a 48V battery bank, there aren’tmany companies that make 48V solar panels. So, in that case, what do you do if you needto charge a 48V battery bank? You would wire multiple solar panels togetherin series, either four 12V panels or two 24V panels to output 72V,
Which will efficiently charge a 48V batterybank, even in very hot weather when the voltage of silicon panels drops low. For an example of the effect that heat hason solar panels, check out this tutorial we did on temperature and silicon solarpanels. So all was well and good with figuring outwhat nominal voltage solar panels to use, just make them match the nominal voltage ofthe batteries, when along came two different technologies that added an interesting twistto the mix. The first was grid tie solar.
With a grid tie inverter, you could now convertthe DC voltage from the solar panels directly into AC to power your house, no batteriesrequired. So the restriction of 12V, 24V, and 48V wentaway. This allowed the solar panel manufacturersto use however many cells they wanted to. For solar panels up to about 300W, the industrysettled on 60 cells. Using the terminology from the battery world,that’s a 20V nominal panel. With an Open Circuit Voltage, or Voc, of around38V, grid tie solar systems were able to string up to 12 or 13 60 cell solar panels in series
and stay within the Electrical Code restrictionof staying under 600V DC, even when taking cold temperature into consideration. If they were using 24V 72 cell panels, theywould be limited to only 11 in series in cold environments, limiting their system size. The second change was still in the batterybased world, with the solar charge controllers that are used to manage putting the powerfrom the solar panels into the batteries. Early on, the shunt or Pulse Width Modulated(PWM) charge controllers had to match the nominal voltage between the solar panels and the battery bank.
UKs John Anthony Talks Organic Solar Cells and Transistors
VO: University of Kentucky chemistry professorJohn Anthony is making lowcost solar cells and transistors out of carbon, instead ofsilicon. Carbon is a lot more versatile than silicone.Silicone is basically a mineral, it’s a rock. Which means you â€¦ are very limitedin, how you can shape it. In order to get the silicone they use in a solar cell, youhave to take sand and heat it with coal at thousands of degrees. Carbonbased materialscan be processed, they can be molded and shaped at much lower temperatures. Right now, we’re working on what’s calleda bulk heterojunction organic photovoltaic.
That’s a lot of big words strung togetherâ€¦to describe a process that is ridiculously simple. You take a transparent conductor andyou basically slather these organics on from a solution like an ink and then the materialsjust spontaneously selfassemble into a working solar cell. One of the grants we just got funding for,we’re trying to get a little more sophisticated in using inkjet printing techniques to makeorganic solar cells. You’d put a transparent conductor sheet of plastic which are easyto make into an ink jet printer and use some of our proprietary inks and â€œzzzzzâ€� andout the other end pops a solar cell.
What can we do on a big scale? The dream Ihave is there are a lot of printing plants that are used to printing highresolution,fullcolor images that are idle, so if we can just design inks to make solar cells thatway, think of the speed at which you could just start printing off solar cells. Lightweight,flexible, you can put them on anything. You know you can coat the windows of skyscraperswith solar cells and start generating some the energy that’s used to cool down theskyscraper. So there’s a lot of potential if we just get the scale up. VO: Outrider Technologies, a company formedin 2005 based on Anthony’s research, is
making organic transistors for flexible, flatpanel displays. We’ve been able to put transistors, basically,integrated circuits on saran wrap, so plastic that’s thinner than thisâ€¦we can wrinkleit up and crumple it and it still works. We actually just submitted this for publicationto one of the nature journals. So we know we can do the basic circuitry and that it’sstable, it doesn’t die when you crumple it up and fold it up and stuff it in yourpocket, right. Then next question is can we get the performance out of it? And that iswhere a goodsized effort of my research group is now turning its attention.
VO: With grants from the Navy, NSF and industrialsponsors, John Anthony’s research team recently moved into the new laboratory building atthe UK Center for Applied Energy Research. Now that I’m out here, I’ve basicallydoubled the number of current, active research grants. Just because now I have the spaceto support people. What we have to do as chemists is, we haveto figure out what needs to be made, we have to then figure out how to make it, and thenwe have to do the initial screening to see if it’s going to have the right properties. My graduate students in my group, right, theyneed to know an awful lot of physics, they
need to know a lot of electrical engineering,they need to know a lot of materials engineering, in order just to figure out what moleculeneeds to be made and then all of their chemical knowledge can come into play. There are few things better in the world thanhaving a different point of view. I really like having ideas thrown at me from everysingle direction and using those ideas to feed into new projects. I can’t tell you how many new projects andhow many grant dollars have been brought up because I’ve gone to a seminar that’scompletely out of my area. And hearing somebody