# Solar Cells Equations

## If molecules were people. George Zaidan and Charles Morton

Say two people are walking down the street, and they bump into each other. They'll just shake it off and walk on. Sometimes that happens with molecules too. They just bounce off each other, and that's that. But what if two people were to bump into each other, and during that collision, one person's arm got severed and reattached to the other person's face Now that sounds really weird, but it's similar to one of the many ways that molecules can react with each other. Two molecules can join and become one.

One can split apart and become two. Molecules can switch parts. All these changes are chemical reactions, and we can see them happening around us. For example, when fireworks explode, or iron rusts, or milk goes bad, or people are born, grow old, die, and then decompose. But chemical reactions don't just happen willy nilly! Everything has to be right. First, the molecules have to hit each other in the right orientation. And second, they have to hit each other hard enough, in other words, with enough energy. Now you're probably thinking.

That a reaction just happens in one direction and that's it. Sometimes that's true. For example, things can't unburn or unexplode. But most reactions can happen in both directions, forward and reverse. There's no reason that our facearm guy can't bump into armless girl, reattaching that arm back to its original socket. Now let's zoom out a bit. Now let's say that you've got a thousand people on the street, and all of them start with their limbs normally attached. At the beginning, every collision is a chance for Person A to transfer an arm to Person B's face.

And so at the beginning, more and more people end up with arms attached to their faces or arms missing. But as the number of people with armfaces and missing arms grows, collisions between those people become more likely. And when they bump into each other, guess what Normalappendage people are reproduced. Now the number of limb transfers per second forward will start high and then fall, and the number of limb transfers per second backward will start at zero and then rise. Eventually they'll meet, they'll be the same. And when that happens,.

The number of people in each state stops changing, even though people are still bumping into each other and exchanging limbs. Now how many people do you think there are in each state Half and half, right No, well, maybe. It depends. It could be 5050, but it could be 6040 or 1585, or anything. We chemists have to get our little, gloved hands dirty ah, well, we're in a lab so not really dirty to figure out what the actual distribution of molecules is. Even though each of limb transfers.

### Meet Leslie Benton of Wholesale Solar

My name is Leslie and I'm a sales technician at Whole Sale Solar and I help our customers design gridtie and offgrid systems for their homes, cabins, boat, RV, Remote Telecom or whatever their solar need may be. I get to work with just a phenomenal group of people a lot of people really just like me. You know, we all love our job, we love what we do but we also love life we love getting out side, spending time with our familes, nature gardening, all the things that keep us happy and healthy.

Working is fun but we also have company picnics at our picnics we play kick ball or Frisbee. We did the mud run last year the Mt. Shasta Mud Run which was a lot of fun I had never done a mud run before so that was a really cool experience. My favorite part of working at Whole Sale Solar, is probably just how much I get to use my brain. You know, we're basically working with Ohm's Law every day Watts, Amps and Volts so it's math equations all day long which I think is really fun and every phone call I get and every customer I help.

#### QEX10 Quantum Efficiency Measurement System Extended Range Calibration

Hello, I'm Michael Kuhr with PV Measurements. Today I will go through the process of calibrating your QE system from 1000 nanometers up to 1800 nanometers in a beam down configuration. I suggest watching the previously posted tutorial of calibrating your system to 1100 nanometers before watching this tutorial. Calibration of the system must be performed anytime the system is turned on, anytime the alignment of the optics is changed, or when changing between beam up, beam down, or reflectance modes. Calibrating the extended range of the system has a unique complexity that the standard.

Range does not. Because no single device is accurate over the full wavelength range of the system, we must use two calibration devices. In addition to the silicon, we use a germanium photodiode that responds from 700 nanometers to 1800 nanometers. Any slight changes between the set up of the measurement can cause errors in the calibration. These errors are most apparent at the point where the two QE curves cross. The good news is this also makes it easy to check if the calibration has been performed correctly. The germanium material is inherently less uniform the silicon material used in our calibration.

Photodiodes. For this reason, the photodiode should be defocused to the point the beam nearly fills the entire active area of the photodiode. This minimizes the uncertainty in the measurement due to the non uniformity. Over the years, PV Measurements has sold various models of germanium photodiodes that may look different then the current model depending on the age of your system. Our current configuration includes a spacer that makes it easy to correctly focus the beam on the photodiode. When the focal point is at the top of the housing,.

The beam is defocussed to the correct amount into the photodiode. I have placed a piece of tape over the photodiode to make the beam easily visible. Notice it is in focus and in the center of the entrance. If you are unsure the beam is entirely in the active area of the cell, observe the main signal level, and move the photodiode into the location where the main signal level is at its maximum. The photodiode should be flat relative to the beam. Pictured here for reference is an older version.

Of our germanium photodiode. As with the silicon photodiode, scan the same range and wavelength increment as you intend to measure your device with. Apply the calibration from 1000 nanometers to the maximum wavelength desired by adjusting the update calibration range numbers from the apply calibration window. If the silicon calibration file appears, click on load calibration data and select the appropriate data file matching the serial number of the photodiode. To check the calibration, measure the photodiode across the 1000 nanometer calibration divide such as from 950 nanometers to 1050 nanometers. Ensure this curve is smooth across.

The calibration division. If there is a bump in the QE, there is most likely an error in the setup of the calibration devices. Double check the setup and calibrate again. As with the silicon photodiodes and any other calibration device, your germanium photodiode should be recalibrated as a regular interval. Our engineers recommend having your photodiode calibrated annually. PV Measurements calibrates photodiodes using photodiodes that have been calibrated at NIST. For technical assistance with your system, contact our technical support engineers at TechSupportPVMeasurements. And for information on calibrating your photodiode, contact our applications engineers at PVMSalesPVMeasurements.

#### Mathematical modeling Functions Mathematics Preuniversity Calculus TU Delft

Hello! Welcome to the first week of the preuniversity Calculus course! Do you remember this from our course promotion tutorial The World Solar Challenge. A race for cars using only solar power to cross Australia. Racing three thousand kilometers from Darwin to Adelaide. Students of the Delft University of Technology built the Nuna7 and won this world championship of Solar cars. How are mathematics like Calculus, important to building a winning car The students of the Nuon Solar team have a clear challenge Design a solar car that can drive the long distance as fast as possible,.

Using only the sun as a power source. This is what we would call a realworld problem. In terms of energy you want to build a car that maximizes power input and minimizes power loss. The first step with such a problem or challenge is analysis You try to break down the question in smaller and more specific questions, like how much power can you harvest from the sun What is the influence of power losses like air friction, roll friction and battery loss Here starts the modeling cycle that is used in science,.

Design and engineering. You have a realworld problem and you try to formulate it in terms of a mathematical model. A mathematical model describes the relation between the different parameters that are of influence in this realworld problem. Such relations are described by mathematical functions. Just a small example of such relations. The power input of the Nuna car is described by a function relating the efficiency of the solar cells, the area of solar cells, the height of the sun and other quantities. Power loss depends on roll and air friction, which both depend on speed and other parameters,.

And loss of electrical power. Once you modeled your problem in terms of functions, you can start making calculations. This often involves solving equations. In particular if you try to find an optimal situation. For example what is the highest speed the Nuna car can attain given certain weather conditions After solving the mathematical questions, you have to interpret the results to predict how a design or phenomenon will work in reallife. And, ultimately, you will have to test your predictions and see whether they are correct, or whether you need another or more refined model.

This cycle of mathematical modeling is used in medicine, economics, science and engineering to tackle real world problems. Think of questions like What is the optimum dose for this medicine How can you maximize the profit of your company How can you design a thrilling roller coaster ride How can you reduce energy consumption In particular, it shows how important it is to have a thorough understanding of mathematics if you want to be a scientist or engineer. This starts with understanding the building blocks of any model mathematical functions. In first two weeks of this course we will review the standard functions like polynomials,.

#### Anna Maria Historic Green Village Tutorial 6 Making Power Heating It Up, Keeping It Cool

Instrumental gtgt Lizzie So a key part of this zero energy equation is to reduce our energy needs. So a huge thing for me probably even more important than the photovoltaics, is insulation. Insulate, insulate, insulate! Just reduce the amount of energy you need to cool down a building or heat it up. Ray We insulated underneath the rafters. The standard in Florida for roofs is R19 we have a much fatter coat on here, we have an R30 roof so we have a lot of insulation that prevents heat from coming inside the.

Building. Lizzie We're using photovoltaic energy which is energy from the sun to generate electricity, we're using thermal energy solar thermal energy where we're using the heat and the energy from the sun to heat up water which is so important in a cafe, you imagine the number of plates that we're washing, and the amount of water we're heating up to make coffee. Ray What a solar thermal panel is is basically it's a flat panel with copper tubing in it and it's painted black and what it does is.

It heats up water. That water will heat to 170 degrees absolutely free. Lizzie And then the third crucial technology is geothermal. We have gone down 450 feet below the Rosedale cafe into an aqua fir where the water temperature is 72 degrees. So all we have to do is bring it up a 450 foot well, pass it through some heat transfer technology and cool down the air in the cafe, or in the Winter, heat the air up and we just said this has to be integrated. The whole thing has to work so that we are very efficiently.

#### Solar Energy Calculator step 3 in replacing your Electricity Bill

Guy injury here you're obviously looking for a solar energy calculator July now if you're looking at 10 a.m. you looking in the solar power systems a khallid spent many months researching sold hell systems and work taylor also you know i saws and summations no osco lost in the information to be until I actually found a system with someone put it all together one school they'll spend a few bucks and go system and prices we solar energy calculator two or three or four months with wasn't on researching.

Because bicycling oh lordy was implement what I told me and and more electricity bills go \$3,400 marked down to nothing unocal box one like it works the other next month a weak sales his bicycle 0 and it's a relief to know that you know that some in the month when old people seem to a raw if electricity is not gonna be wonderful yes i cud so look world's a flea on solar energy calculator just making these tutorials to help other people following you my shin of am because it's a godsend i cud either in the.

#### TU Delft MOOC Preuniversity Calculus Review your high school mathematics

Get ready for calculus! The world solar challenge. A race for cars using only solar power to cross Australia. Racing 3000 km from Darwin to Adelaide. Students of the Delft University of Technology build the Nuna 7 and won this world championship of solar cars. How are mathematics like calculus, important to building a winning car To design the NunaCar, we need knowledge of Solar cells,Mechanics, Aerodynamics, Materials and Electronics. Our team consist of students of almost all majors offered Delft. Every member of the team must have a solid background in mathematics.

During the design process a lot of elements need to be modeled and calculated. For example think of a model for the power our solarcells can generate, and that in different conditions. My role as a mathematics student is to calculate the optimal strategy depending on the weather, battery level and the time left that race day. The necessary tools to mod the reality and make predictions are treated in our calculus courses. Is your dream to be an engineer or a scientist and are you gonna start university As the nuon solar team explained calculus will be an important topic. It's a essential part.

Of any engineering study. The aim of the preUniversity calculus course is to give you, a great start at University. There are 4 main topics the first topic is functions, essential for building mathematical models. Solving equations is the second topic important for making predictions. Finally Differentiation and Integration which are the tools to study any phenomenon that varies in time and place. We will help you to get a good understanding of these topics. During this course you will practice a lot and learn from common mistakes, students of the Delft University of Technology will share their study experiences and tips with you.

#### Tutorial Photoconductivity

MUSIC PLAYING PROFESSOR Hello, everyone. In our last demo, we demonstrated how the electrical conductivity of silicon can be changed by over six orders of magnitude by adding dopants that can increase the number of free or mobile charges in the material. Today, we'll show how we can use light to break electronic bonds and silicon, and create free mobile charges. The principles we'll be using today can be applied to everything from sun screen, to of course, solar cells. We'll use the undoped, or intrinsic silicon sample from our last demo, and measure how the conductivity changes.

When we shine light on it. Our set up is identical to that of last time. We'll take a piece of silicon with metal contacts. We'll use an ohmmeter that we connect to our sample via metal wires to measure its conductivity. The measured resistance will be determined by the conductivity and the size and shape of our sample. Finally, we represent the connectivity in terms of our measured values and relate it to the number of free, mobile charges, and the material properties of silicon. We'll first measure the conductivity of our sample.

In the dark, and then shine light on our sample and see how the conductivity changes. Our ohmmeter is hooked up to our sample, and we measure a resistance of around 120,000 ohms, which is equivalent to a conductivity of around 0.0002 inverse ohm centimeters. Now, let's flip on the light. We can see that we measure a slightly lower resistance of around 40,000 ohms, but what is light doing to affect the conductivity so much. Let's zoom in to the atomic level and explore why. We see here a 2D representation of a pure silicon crystal where.

All the valence electrons form rigid covalent bonds, are immobile, and don't allow the flow of electricity. This material structure is identical to our intrinsic sample when in the dark, which has a very low conductivity. When light hits our sample, photons of sufficient energy can break these covalent bonds, injecting the formally immobile electron, giving enough energy to move around. The mobile electron leaves behind a mobile hole, which can move through the crystal by swapping positions with neighboring covalently bonded electrons. This explains why the light increases the conductivity of our sample.

Again, our conductivity is determined primarily by the number of mobile charges. Light creates additional pairs of mobile electrons, and holes, thus increasing n and our conductivity. We've demonstrated that light is able to generate fee carriers in our ultrapure sample. The same effect still happens in dope silicon, but the light induced change in conductivity only creates a small relative change that we can't measure using our ohm meter. Generating these extra mobile charges by breaking covalent bonds with light is the source of the electricity that we eventually collect in our solar cell.

#### Make a Zinc Air Battery

Warning Concentrated sodium hydroxide is very corrosive, wear gloves when handling it. Greetings fellow nerds. In a previous tutorial i made an aluminumair battery. It wasn't very good and produced very little current. In this tutorial we're going to make a zincair battery. First we make our sodium hydroxide electrolyte by getting 150 milliliters of water and adding to it about 50 grams of sodium hydroxide. Stir the mixture until it dissolves. Be careful as the solution will get very hot. When it's done, set it aside and let it cool.

While that's happening, we'll build the rest of the cell. I'm going to use this 200 milliliter beaker. For our anode, or negative electrode, we use a large sheet of zinc metal. We originally got this sheet out of a carbon zinc battery from a previous tutorial. For the cathode, or positive electrode we'll again be using steel wool. Now get some wires with alligator clips and attach them to the electrode materials. Get a paper towel and wrap the steel wool, the idea is that we don't want it to touch the zinc metal.

Now get the zinc metal and wrap it over the paper towel and steel wool. Push the entire assembly into the container. Make sure the wool on top is exposed so air can get in. At this point this is known as a dry charged zincair battery. It won't work until we add the electrolyte, but it can be stored for decades like this until you need it. To activate it, we just mix up and pour in the sodium hydroxide electrolyte. And that is a zinc air battery. Let's measure its output.

Connecting it to the multimeter we see the voltage is around 0.84 volts. Let me measure the current. Whoa, it's off the scale. Let me switch the multimeter to high current mode. Let's give it a few minutes to stabilize. The current is very good at 0.670.68 amps. This is much better than the 17 milliamps of the homemade aluminum air battery of the previous tutorial. The reactions are similar, the iron is catalyzing the reaction of oxygen and water to make hydroxide while the zinc metal reacts to make sodium zincate.

What makes this battery work better is that the sodium zincate is soluble and doesn't block the reactions like the aluminum oxide formed in the aluminum air battery. That's why we can get a much higher current. We can't use sodium hydroxide for the aluminum air battery because aluminum metal reacts with sodium hydroxide itself to produce hydrogen. This wastes power and renders the cell dangerous to use. Commercial cells get around this by using better chemicals and aluminum alloys but that's beyond the ability of most amateur chemists. Anyway, thanks for watching, please subscribe like and comment.

#### How To Build A Solar Panel Part 14 School Series Part 1

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#### How To Build A Solar Panel Part 16 School Series Part 3

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