Solar Energy

[ReadYourBible]

The 19.9 MW Gemasolar solar plant in Spain features 15 hours of storage and can supply power 24 hours a day.

Photo courtesy of Wikipedia

 

 

In an effort to share what I have learned, I'd like to take the opportunity to write down some notes I've compiled from www.pveducation.org.   For those of you that have an interest in solar, installation of solar, considerations for solar this would be a good place to start.  This is written purely from a functional standpoint, much like a 'How to Guide'.   While my main area of function involves organic photovoltaics, these notes most accurately describe the workings of a Silicon solar panel and their considerations.  However, the information is somewhat interchangeable. 

 

I.  Introduction to Solar Energy

 

Solar is the source of all energy on earth, humans and ultimately all forms of life rely on the  sun for warmth and energy.

Fossil fuels (not dinosaurs, but rather plant matter) is current used for transportation/energy is essentially stored solar from   millions of years ago. 

 

Other forms of energy include:

Biomass

Wind

Water

Geothermal 

 

Photovoltaics (PV) is the way in which we harness the suns energy.  By converting incident radiation into electricity, PV's are noise free, produce no pollution (I have really? written here, because the manufacturing process/R&D produces elements that would be considered pollutants), and are often long lasting.  

 

II.  History of the PV

Space industry driven in the 60's, due to the requirement of a power source that was separate from the grid for satellite functions.  It was utilized on the Apollo Lunar Module seen here:  http://en.wikipedia.org/wiki/Apollo_Lunar_Module

 

Other driving forces in history include the oil crisis in the 70's.  

 

Greenhouse Effect 

Solar is a very desirable form of energy source, as it is considered to be environmentally benign.  It is thought that through solar we might be able to reduce carbon based emissions generated from fossil fuels. 

 

 

 

 

[ReadYourBible]

Photo courtesy of 

https://sites.google.com/site/sotascientific/Home

 

Properties of Light 

 

Visible light is only a fraction of the total energy that is emitted by the sun.  

 

Planck/Einstein

 

Planck described how photons of light were thought to be discrete packets of energy, whereas Einstein coined the Photoelectric Effect

 

To understand light, you need to understand that photons have a property what physicists would term as wave-particle duality.  Something that is most commonly described in a mathematical sense by quantum mechanics.  

 

So we can say that the photon is a wave packet.  Which is a collection of waves which interact in such a way that the wave packet may be spatially localized and form a square wave.  http://en.wikipedia.org/wiki/Square_wave  However, it may also behave like a sinusoidal wave http://en.wikipedia.org/wiki/Sinusoidal_wave, and it is here that the photon behaves as a particle.  

 

Energy of a Photon

Photons are characterized by their wavelength, or an energy.  There is an inverse relationship between the energy and the wavelength that is described by this equation:

 

E = hc/wavelength ---- h is Planck's constant, c is the speed of light all over the wavelength.  

 

h = 6.6 x 10^-34J

c = 3.0 x 10^8 m/s  

 

h*c = 1.99 x 10^-25 J/m

 

This above inverse relationship means that the light consisting of high energy photons (blue light) is equivalent to a short wavelength.  Light consisting of low energy photons (red light) is described as having a long wavelength. 

 

 

Particles, photons/electrons energy parameter is described in eV (electron volts) as opposed to Joules.  So to raise eV energy through 1V, this means that a photon with the energy of 1 eV is equal to 1.6 x 10^-19 J,  but in order to use this we have to rewrite the equation of hc as follows: 

 

h*c = 1.99 x 10^-25 J/m * 1 eV/1.6 x 10^-19 J = 1.24 x 10^-6 eV (m)

 

Then we would convert this number into a usable one (the unit of wavelength) em

 

h*c = (1.24 x 10^-6 eV/m) x (1.0 x 10^6 um/m) = 1.24 eV (um)

 

By expressing the equation for photon energy in terms of eV, and um (micrometers) we arrive at an expression that allows us to relate photon energy to wavelength, as shown by the following equation:

 

E(eV) = 1.24/wavelength (in um)  exact value of 1 x 10^6 (hc/q) = 1.2398.

 

Bear with me here as I go through the math to get to how it works.    We've still got a bit more, but it all ties together and makes sense!  

 

 

 

 

 

 

 

[ReadYourBible]

Photon Flux - defined as the number of photons per second, per unit area

 

Photon flux = # of photons/sec m2

 

Important, as it is used to determine the number of photons generated, and ultimately the current produced from a solar cell.

 

Photon flux DOES NOT give information about the energy (or wavelength) of the photons, this must be specified.  At a given wavelength these parameters (photon wavelength, energy or flux) can be used to calculate the power density for photons at a particular wavelength.  

 

Power density is calculated by multiplying photon flux by the energy of a single photon.  This gives us the # of photons striking the surface at a given time, and multiplying by the energy of the photons comprising the photon flux gives the energy striking a surface per unit time, which is equivalent to power density.  

 

To determine power density (W/m2) the energy of photons have to be in Joules

 

H(W/m2) = photon flux x hc/wavelength

H(W/m2) = photon flux x q (1.24/wavelength (um)) for wavelength in um

H(W/m2 = photon flux x qE (eV) for energy in eV

 

q = electron charge 1.6 x 10^-19 

[maladee]

so i do no t get it?

[trottigy]

so i do no t get it?

 

Sure you do - every time the sun shines 

[ReadYourBible]

I'm not finished yet there's more

so i do no t get it?

 

Sure you do - every time the sun shines 

[zoebarry]

I don't understand why this was posted.........

[maladee]

it is a mystery

[tekmantwo]

I don't understand why this was posted.........

It is no mystery.....

 

Re-read the first sentence, first post...

 

Our dear Sister is sharing her knowledge with us.....and I, for one, am grateful...

 

Thank you Sharon....

[mdj]

I don't understand one word nor one cypher of the explanation of sister Sharon in her posts - But how I love it!
I am so proud of her and have deep respect for such intelligence.
 

[Lance]

In reading my astronomy books .. I found it interesting that it takes from 10,000 to a million years for a single photon generated at the fusion core of the sun .. To work it's way to the surface .. And yet it only takes 8 1/2 minutes for it to reach us...and delivery it's packet of energy..

Edited June 25, 2013 by TheDoorGuy

[jayrtom]

In reading my astronomy books .. I found it interesting that it takes from 10,000 to a million years for a single photon generated at the fusion core of the sun .. To work it's way to the surface .. And yet it only takes 8 1/2 minutes for it to reach us...and delivery it's packet of energy..

For the photon all that happened while he blinked is "eyes"

Sent from my GT-I9300 using Tapatalk 4 Beta

[Lance]

Here is a simplified explanation for those who forgot their high school science..

What is light? It is a form of electromagnetic radiation .Realize that we are dealing in theories here.. Not all aspects of electromagnetic radiation have been nailed down..

Electromagnetic radiation has a dual nature as both particles and waves.

One way to look at it is as changing electric and magnetic fields which go through space, forming an electromagnetic wave.

This wave has amplitude, which is the brightness of the light, wavelength, which is the color of the light, and an angle at which it is vibrating, called polarization.

This was the classical interpretation, crystallized in Maxwell's Equations, which held sway until Planck, Einstein and others came along with quantum theory.

In terms of the modern quantum theory, electromagnetic radiation consists of particles called photons, which are packets ("quanta") of energy which move at the speed of light.

In this particle view of light, the brightness of the light is the number of photons, the color of the light is the energy contained in each photon, and four numbers (X, Y, Z and T) are the polarization.

This packet of energy which comes from the sun is very powerful.. So our atmosphere and magnetosphere filters out harmful parts of these packets. We know we can still get damaged by these packets of light. The ultra violet part of light can burn your skin.. The infrared part can cook you .. Etc

So how do we convert this light energy to electrical energy...

It's these photons arriving from the sun and hitting the solar panels that cause electrons ultimately to move down a wire.

What happens when the photons hit the solar panels?

As Solar panels, like everything else, are made up of atoms and atoms contain electrons. When a photon hits an electron, the photon and it's energy packet is absorbed by the electron. Since this electron now has more energy, it breaks free from the atom.

But if that were all there was to it then we'd just have a bunch of loose electrons moving around randomly. Like kids on sugar...

Something has to organize them to get them to move in one direction down a wire.

Doing that is a big part of the solar panel's job. A typical solar panel is made up of two layers of slightly different materials. Keeping the explanation simple, the result of the two layers is that these free electrons get pulled to one layer and away from the other layer, resulting in the electrons moving in one direction only.

If we then connect one end of a wire to one of the layers and the other end of the wire to the other layer, these electrons that have gotten their energy from the photons and that have been forced to move in one direction only, will now move along the wire. And if we go further and split the wire somewhere along its length and put an applicance there, one that works using moving electrons, then we will be powering that appliance..or if we put a battery along this wire we can store this energy...

Sharon I hope I have basically got this right...

[ReadYourBible]

I don't understand why this was posted.........

In another area of the forum, someone expressed to know more about solar energy.  So I created a new post, and hope they'll find their way here.  When I'm finished, I will go back to the original post and let them know its done.

it is a mystery

Nope.  LOL

It is no mystery.....

 

Re-read the first sentence, first post...

 

Our dear Sister is sharing her knowledge with us.....and I, for one, am grateful...

 

Thank you Sharon....

You're welcome, solar is something we can use right now too.  I've got lots more to post, so I'd better get on it.

I don't understand one word nor one cypher of the explanation of sister Sharon in her posts - But how I love it!

I am so proud of her and have deep respect for such intelligence.

 

It's a bit technical right now, but the math jargon will ease up, and we'll get into considerations on how to install solar panels and how to get the best efficiencies out of them.  

 

Also, I'm sharing this information from www.pveducation.org, I've just took the most important points out of the rather long, and countless pages of information and am making it (hopefully) easy to use and reference at a later point!  

[ReadYourBible]

Sharon I hope I have basically got this right...

Seems legit!  All kidding aside, this is correct.  

 

A lot of people install solar panels, or have them installed without really knowing what's going on, this information will help them with that.  Also if they have someone install it for them....they could avoid people who are less than well versed in the whole process.  Musky was saying a brother did this for one of their assembly halls, which is fantastic -- because he won't try to sell them things they won't need, or worse yet scam them.  At least with this sort of info, you can know if that person knows their stuff or not!

[trottigy]

I have looked into solar for my house - not worth the money - yet.

 

I pay on average $125 a month for electricity. If solar covered it ALL (which seems unlikely) a years worth of savings would be $1,500. Most of these "home" systems cost $6,000 - $10,000. That means 4 - 7 years to recoup the costs. Many are only good for 5 years MAX and need parts replacements - at least under the desert sun. As we say in construction - it just doesn't seem to "pencil out".

[ReadYourBible]

Spectral Irradiance

 

Function of a photon wavelength or energy denoted by F, is the most common way of characterizing a light source.  It gives a power density at a particular wavelength.  Units of spectra irradiance are W/m2 um

 

W/m2 - power density at the wavelength, therefore m2 is equal to the surface area of that light emitter & the um refers to the wavelength of interest.

 

In the analysis of solar cells, photon flux is needed, as well as the spectra irradiance.  The spectral irradiance can be determined from the photon flux by converting the photon flux at a given wavelength to W/m2

 

Result is then divided by the given wavelength  F(wavelength) = (photon flux)E 1/change in wavelength in SI units.

 

If this is of continued interest...... check out this portion of the site, as there are graphs. http://www.pveducation.org/pvcdrom/properties-of-sunlight/spectral-irradiance

 

Solar Radiation

 

The Sun is a hot sphere of gas, with an internal temperature of 20 million degrees Kelvin (this is 1.999997 x 10^7 Celcius) this is due to nuclear fusion reactions, which are converting Hydrogen to Helium.

 

Radiation from the inner core is not visible, as Hydrogen atoms on the surface absorb it, and the heat is transferred via convection.  

 

The surface of the sun, or the photosphere is at a temperature of nearly 6000K, or 5726 degrees Celcius, and closely approximates a black body (https://en.wikipedia.org/wiki/Black_body)

 

Total power of the sun is calculated by multiplying the emitted power density by the surface area of the sun, which gives us 9.5 x 10^25 W of energy  Currently the world uses 15 terrawatts or 1.5 x 10^3 W.  Thus Solar has the potential to provide 1575 EJ (or 438,000 terrawatt hours worth of energy)

 

Total power emitted from the sun is composed NOT of a single wavelength, but many, thus appearing white/yellow to the human eye.  The different wavelengths can be seen by holding up a prism and passing a light through it, or even via the rainbow.  

 

Different wavelengths produce different colours, however not all are visible.  Some are invisible to the human eye.  

 

(Does all of this ^^ not give you goosebumps?  Jehovah CREATED this.  I was in awe when I read the above.  We get enough energy via the sunlight in ONE DAY to supply the entire world with energy for the whole YEAR.) 

Edited June 25, 2013 by cerebral ecstasy

[ReadYourBible]

I have looked into solar for my house - not worth the money - yet.

 

I pay on average $125 a month for electricity. If solar covered it ALL (which seems unlikely) a years worth of savings would be $1,500. Most of these "home" systems cost $6,000 - $10,000. That means 4 - 7 years to recoup the costs. Many are only good for 5 years MAX and need parts replacements - at least under the desert sun. As we say in construction - it just doesn't seem to "pencil out".

Exactly the problem.  I'm in the organic photovoltaics field, we're working on plastic OPV's that can take the place of the Silicon panels that are super expensive.  It's not far off.  

 

http://en.wikipedia.org/wiki/Organic_solar_cell

 

You do have an advantage in living in the desert though, less cloud cover so more energy conversion occurs.  I'll be getting into that a bit later on.  (All the considerations, dependent on where you live).

 

Oh, and I think you have the advantage of selling back to the grid too, we don't have that here.  If we generate our own power, we just have it taken off our power bill.  We can't actually make any money off it.  

Edited June 25, 2013 by cerebral ecstasy

[trottigy]

Yeah, NV Power doesn't let us sell back either.

 

The other big hold back - is the batteries. You have to have some place to store that energy so it can be used when there isn't sun light or to at least have a "steady" / "constant" flow of power. And these are the items that WILL need replacement and aren't cheap!

[jayrtom]

I have looked into solar for my house - not worth the money - yet.

I pay on average $125 a month for electricity. If solar covered it ALL (which seems unlikely) a years worth of savings would be $1,500. Most of these "home" systems cost $6,000 - $10,000. That means 4 - 7 years to recoup the costs. Many are only good for 5 years MAX and need parts replacements - at least under the desert sun. As we say in construction - it just doesn't seem to "pencil out".

Exactly the same here in Portugal... Only even more expensive... The costs you mentioned are just for water heating... For electricity its 4x more, but the electricity we pay is the same figure and the incomes around 4x less

20 years ago me and my boss at the time developed a machine that worked with solar system alike in the focus of a bunch of parabolic plates. The system was programed by a PLC (no visual development back then) in order for the thing to point allways to the sun from morning to night, summer or winter... Unfortunately the company run out of funds and it never got to serial production... Never saw anything similar since then..

Sent from my GT-I9300 using Tapatalk 4 Beta

[ReadYourBible]

Exactly the same here in Portugal... Only even more expensive... The costs you mentioned are just for water heating... For electricity its 4x more, but the electricity we pay is the same figure and the incomes around 4x less

20 years ago me and my boss at the time developed a machine that worked with solar system alike in the focus of a bunch of parabolic plates. The system was programed by a PLC (no visual development back then) in order for the thing to point allways to the sun from morning to night, summer or winter... Unfortunately the company run out of funds and it never got to serial production... Never saw anything similar since then..

Sent from my GT-I9300 using Tapatalk 4 Beta

That's really too bad.  I've programmed PLC's in class, and I found them to be quite interesting, especially with the visual overlay that is available now.  I'm trying to recall the program we used.... but that was 2 years ago!  

[ReadYourBible]

Yeah, NV Power doesn't let us sell back either.

 

The other big hold back - is the batteries. You have to have some place to store that energy so it can be used when there isn't sun light or to at least have a "steady" / "constant" flow of power. And these are the items that WILL need replacement and aren't cheap!

Grrr

 

Yes, storage is always an issue.  In tandem with the solar we're researching, we have a partnership with another set of researchers that are looking at this problem as well.  That being said....

 

There's a new battery that is on the market that may be able to address this need already, I recall reading about it as part of one of the headlines of late.  

 

I think it may have been this one: http://www.sciencedaily.com/releases/2013/06/130611082229.htm

 

I hate this system.

Edited June 25, 2013 by cerebral ecstasy

[maladee]

 I do not mean to make fun of you if that is how you took it , i just do not know where this thread is going? have they addresed the water issue that you need to use up for cleaning these panels, it is alott , I am part of a team that is working to install panels we have done so on one asembly hall out here I do find it amazing, back in the day I was a elecro-mechanical tech, so this is interesting.

[ReadYourBible]

Sherry, I'm sharing what I've learned thus far, and what I've learned is how installation angles, where your panel is located, and what location you live in is a crucial consideration and this is 'where its going'.  

 

If it's of benefit to you great, if not, that's okay too.   I'm guessing the cleaning of the panels will be addressed by nanoscale patterning that is built into the panel.  http://www.solarguide.co.uk/new-self-cleaning-glass-could-be-used-in-solar-panels

 

Or via a product that is applied afterwards.  http://www.nanoshell.co.uk/protective-coatings/solar-panel-pv  (this would help in the cleaning)

Edited June 25, 2013 by cerebral ecstasy

[Lance]

My expirence about light comes from dabbling in astronomy and photography..

To help people to appreciate how much electromagnetic radiation commonly called sunshine ..it can basically be explained in the terms of light bulbs.

Think of it this way for every square meter at the earths surface at midday ..

We recieve about 30 watts of ultra violet light...

About 450 watts of visible light

And about 525 watts of infrared light ..

Too much of one and not the other..etc... throws our essence of life into a death spiral.. I wonder who came up with the right ratio and amount.. We are wonderfully made

So when it comes to solar power.. They are always looking ..to lower cost of production and to find materials that are efficient at converting electromagnetic radiation into electrical energy.. The holy grail on energy production is probably cold fusion..which is another topic altogether .. Interestingly One of my customers is trying manufacture a nano sun.. The problem is how get it going.. How to keep it going.. And how to contain it without blowing up..

Jehovah knows ...