Photovoltaic Cells

The skyscrapers in Mexico City will be interested in this discussion.

just a question from your answer I'm assuming that they have a certain rate

Yes, a PV cell will operate the same whether on the roof of a house or a skyscraper, all other factors being the same. Being closer to the sun will have no effect.

until the next shaker hits the old lake bed they built the place on

Perhaps it would be better to use big-ol' windmills since the wind will certainly be faster at the top of the sky scraper than on the ground.......

Thank goodness the energy density of sunlight does not change much with altitude. If it did, it would be heating the atmosphere past the point of being a habitable planet.

Physics? Who needs physics.....?

]okay on that note what roll would a magnifying glass play in between the Sun and the p?hoto valtic cell?? And couldn't we incorporate water in the panels of the photo valtic cells to also transform energy? Just saying

depends on what gauge the foil is on your hat that day

The power generated by solar cells mounted on houses in Denver, Colorado at over 5,000 feet elevation, make more power than cells located in Death Valley, California, at sea level. I wouldn't know how to measure this minuscule difference in output.

Skyscrapers, I don't know, but the tops would be out of the densest air pollution and would, therefore, probably produce more power.

That's also why satellite TV dishes are mounted on the roofs of houses and not the ground. That puts the antenna as much as 15-17 feet closer to the satellite.

And that's the truth!

lyn we're finally in agreeance all things are relative

furthermore I believe , that magnifying the sun's energy on a phot voltic cell would allow us to stack the cells , and point them directly towards the magnification and less space to transform that energy and we would use less cells. today is January eighth 2013 I am having a little conversation with my friends I'm CR 4.

so we're clear I am talking about magnifying the Sun energy pointing that magnification directly at a stack of photovoltaic cells , saturating them with .the sun's energy

sounds like a concentrator to me

Concentrating collectors are not new, I built my first nearly 50 years ago....


http://inhabitat.com/new-solar-panel-array-doubles-the-energy-and-halves-the-cost-of-traditional-solar/amonix-nrel-2/

seems to be a much more efficient way why are they not incorporated home installation ? hi cost

they work great and make a ton of heat that has to be dealt with

The main reason I think is the requirement of alignment, the fresnel lens apparatus must be pointed directly at the sun to work at it's peak efficiency....

http://techtransfer.universityofcalifornia.edu/NCD/10320.html

Here's a cost analysis....

http://www.irena.org/DocumentDownloads/Publications/RE_Technologies_Cost_Analysis-CSP.pdf

Solar tree....

http://howsolarworks.1bog.org/solar-panel-efficiency/

Quick question... Do Solar Eagles nest in Solar Trees??????

No, not solar tree's, in tall buildings by the sea....

I am working off of my phone so I can't clearly see all detail are those concentrators an array of photocells a fixed in the shape of a funel to capture more energy in a given space ? or are they reflecters reflecting the sun's energy down to 1 photocell at the base? I am talking about magnification

The difference here is the cell design, called multi-junction cells they have 2 or 3 layers that absorb solar radiation at various wavelengths....

http://www.reuk.co.uk/40-Percent-Efficiency-PV-Solar-Panels.htm

The usual reason is economics.

It's cheaper to just add more solar cells, instead of using tracking, lens or concentrators (as well as the additional cooling, heavier support structures, yearly cleaning, periodic realignment etc).

As usual, either all the experts are stupid OR there's something you've missed.

I have seen a system built for a home that had Fresnel lenses and a tracking system that used an inert solution to cool down the panels. Don't remember the coolant but think it was mineral oil or distilled water. been a while ago. It worked very well for them but it took a lot of trial and error on the tracking system to get it to function correctly. Back then they did not have access to tracking software like they have today for their telescopes to do the tracking every kid with a telescope today has tracking software on a laptop or their smart phone app to do the job. It is doable just not as practical when you can add a few more panels unless you don't have the space. And if you don't have the space watch out for complaints from neighbors that you are blocking their view it does happen. Duke

How are you going to mount that huge lens to keep the wind from blowing it off or misaligning it? Good luck collecting your fire insurance if it focuses on the roof! BTW, choose your friends wisely.

The difference between the elevation of a house top and skyscraper top to the sun is negligable compared to the distance between the earth at the tropic of capricon in December and the tropic of cancer in June.

In 2013 that difference is about 3,110,000 miles. That's not much difference compared to the average 92,955,807 miles.

I would be more concerned with climate patterns where my solar cells are located.

The tallest skyscraper in the world is about 1/2 mile high. I compute the increase in solar radiation due to it being closer to the sun as (93000000.5/93000000⁾² or about .000001%. There is much more loss with transmission through the air, but that also is down in the noise. A skyscraper is probably much worse being close to the pollution of a city. You're best off in the countryside or better still in a desert with miminal cloud cover.

i understand the concentrator and reflecting more light to the cell. But what about simple magnifying lenses between the cells and the sun. We can see the outer reaches of the universe at least we believe we see the outer reaches of the universe by magnification why wouldn't that principal work for solar cells to increase its efficiency? like I said magnifying lenses that point directly at the concentrator ?

It would, it's just that the fresnel lens design is much cheaper, achieves the same result, is less bulky etc....The Fresnel lens was originally used on lighthouses(shown below)...

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

As you can see from the above post on cell design, they are working at the power of 500 suns!

The problem is that 70-80 percent of the light falling on a solar cell is converted to heat, not electricity. Concentrating the light generates more heat, and the efficiency goes even lower when the silicon gets hot. So you have to cool it, and probably have some tracking mechanism as well. It boils down to economics - the complexity versus more solar cells. Apparently it's not worth it since it seems nobody is doing it.

If you look at the inverse square law and calculate the difference in distance you will find very little (if any) difference.

The energy change as a function of the distance from the sun is not near important is what the map location of the installation is resulting in what is called the solar insolation or irradiance (look it up http://en.wikipedia.org/wiki/Insolation). This can be > 25% change in a few 10s of miles and is a function of the local atmosphere. Some of the highest insolations in the world are in the south west US!

As far local altitude goes (ground or on top of building), higher is always better for a number of reasons; some already stated. However, what has not been stated is the single biggest loss of output on a panel in its lifetime - dirt and dust. Add dewing on the dust and the dried mud left over can reduce power by 50%! There are already solar power plant washing services that you can hire and in some case well worth the cost.

The cost to added on a tall structure and the addtional equipment needed to raise the panels and structure itself adds cost and in some cases too much cost.

Another big benefit for putting PV up on a structure is that the panels keep the structure cooler (by a lot) and therefor less AC is needed. And then there is the fact that the roof lasts longer, fewer rodents to chew wires are around, less exposed wiring to AC panel, and finally fewer rocks and things breaking panels........

Put it on the roof, BUT still plan on a at least a yearly washing.

Good luck!

is not near important is what the map location of the installation is resulting in what is called the solar insolation or irradiance
Which is why solar is not big in Seattle.

Although the distance from the Earth to the Sun is being diminished very little by putting the photo voltaic (PV) panels on a higher perch such as a skyscraper, the larger advantage is getting above some of the air pollutants which can cause a much larger difference in PV efficiency.

As for higher temperatures lessening effeciency and trying to offset that with additional panels...... the higher temperatures of the panels not only decrease efficiency but also shorten the life of the panels.

I was considering adding a water misting cooling system to my PV system but that can cause other problems such as mineral deposits. I guess that problem could be solved by adding a filtration system.

I would point you at a video course from Stanford with the title Solar Cells, Fuel Cells and Batteries. In the introductory section there is an explanation of the Energy available at the Earth's surface from the solar radiation, taking into account your latitude and the absorbtion by the atmosphere.

The couse also explains the limits to the conversion using semiconductors and why and how the temperature of the cell affects this effeciency, and why cooling the cell is not neccessarily cost effective except where temperatures are high enough, say in concentrator set ups.

It did not explain why the photo-electric effect at a surface hadn't been used for solar conversion, but seems to have been relegated to low output devices e.g. light meters. I would have thought these could have been developed as temperature would enhance electron emission, but I can see the difficulties of maintaining a vacuum in a package that would need to be robust, and it wouldn't have been able to piggyback on the vast silicon foundry industry.

The next generation of solar pv cells will probably be thermionic capability added utilizing both heat and light, and well suited for concentrating collectors....

http://large.stanford.edu/courses/2010/ph240/brown-cohen2/

http://en.wikipedia.org/wiki/Thermionic_emission#Photon-enhanced_thermionic_emission

http://micropower-global.com/

Thanks SolarEagle for the PETE info.

More complex than what I was contemplating, which was to leave the semiconductors aside and look at an enhanced, reduced form of thermionic triode, (with the minimal vacuum gap) which would have the advantage of output control - maybe.