Dear Friends, Visitors/Viewers/Readers,

This is a repost from one of our sister publications, Windermere Sun, below:

Perovskite solar cells (Attribution: Stanford ENERGY, video by Mark Shwartz, https://creativecommons.org/licenses/by/2.5/, Presented at: WindermereSun.com)

(Please click on red links & note magenta)

Back in 2015, I interviewed the Chief Technology Officer Dr. Christopher Case of Oxford PV during the InterSolar North America in San Francisco, CA. Dr. Case introduced me to a potentially game-changing solar technology, the perovskite solar cell technology, that holds much promise for lowering the cost and boosting the performance of solar power by increasing photovoltaic efficiency of any solar photovoltaic thin film material to 30+% in a perovskite tandem layer (which is more than the maximum efficiency achieved in traditional mono-and poly-crystalline silicon cells).  In laboratories, perovskite cells are manufactured by spin-coating, spraying, or “painting” them onto a substrate (material that provides the surface for the chemicals to crystalize on).  Perovskites are only about half a micron thick while silicon layer is roughly 200 microns. The main hurdle for perovskite is durability. Perovskites are very sensitive to oxygen, moisture, and heat, therefore, requiring heavy encapsulation to protect the cell, leading to increased cost and weight of solar cell. Oxford PV’s tandem cell conversion efficiency is 29.52%. More research and development and data are needed for testing its efficiency, stability, as well as increasing lifespan and replacing toxic materials with safer ones. Company such as Saule Technologies has some very interesting perovskite products in the works: 1. they have a perovskite photovoltaic glass ( a semi-transparent perovskite solar cell printed onto flexible foils and overlayed with layers of glass), making it a window that generates electricity. 2. Saule is also producing energy-harvesting sun-blinds that can block intense summer sunlight, and allowing sunlight to enter the building in mornings and evenings to provide natural light and passive heating. These blinds can be adjusted manually or automatically. 3. In May of 2021, Saule launched the world’s first industrial production line of perovskite solar panels in Poland. Jinko Solar is also working on rolling out perovskite technology. The perovskite solar cell could be the future of energy, in the video published on Sep. 14, 2021, “Perovskite Solar Cells Could Be the Future of Energy“, below:

Perovskite mineral was discovered over 150 years ago, but it’s only recently that scientists have been able to synthesize the properties of the material in laboratories using commonly available chemicals. And what they’re finding is that it can give a big boost to the performance of existing solar cell technology. This week we take at look at how it works, in the video published on Aug. 9, 2020, “Perovskite Solar Cells: Game changer?“, below:

In the video published on March 26, 2021, “Perovskite solar out-benches rivals-2021| perovskite solar cells shines a little brighter“, below:

Perovskite, a calcium titanium oxide mineral discovered in the Ural Mountains of Russia in 1839. This new old material is generating quite an explosive buzz because scientists have found, in recent years, that it is a great material to be used in solar absorption applications. It can be made simply and inexpensively by using common wet chemistry lab methods and low cost equipment instead of the expensive deposition equipment common in the semiconductor industry. To take a look at how this process is made cheap and accessible, I’m sharing the video below:  

These solar (photovoltaic) cells are made in tandem (layer by layer) fashion on a specially coated glass support. In the video above:

1. the glass is coated with a dense layer of titanium dioxide, by robotic arm, to prevent electrical charge generated by sunlight from leaking out of the cell.
2. a less dense porous oxide layer covers the dense oxide layer (usually titanium dioxide, other oxides may also be used).
3. a simple high speed spin coater deposits this layer from solution and spreads this coating evenly across the device.
4. heating this glass/device in an oven conditions it for solar cell use.
5. prepare the Perovskite material (which absorbs in the broad range of solar spectrum) by combining 2 precursor materials:   PbI2 (lead iodide) & CH6IN (methylammonium iodide)
6. drip the liquid phase mixture (from 5.) onto the oxide coated device (from 4.)
7.  spin the resulting device in 6 to assure even coating
8.  applying halide solution
9.  heating the device resulting from 8 on a hot plate–>spontaneously crystallizes precursors in freshly deposited liquid
10.  color changes also result from crystallization process resulting from 9.

Such tandem product has the advantage of being able to be introduced into existing infrastructure of current silicon module manufacturing process, boosting its efficiency. With added few steps toward the end of the production line, the coating (equivalent to second solar cell) takes advantage of the blue portion of the solar spectrum and may improve the solar cell efficiency by 20-25% above the underlying silicon. The fact that Perovskite-based solar cell technology is of earth abundant material also insures its availability and low cost. Its high absorption in solar spectrum enables it to have comparable characteristics to that of gallium arsenide. Its ability to change its sensitivity to different band gaps in solar spectrum allows it to make different architectures in tandem solar cells. It can truly be considered as the Custom Solar Absorber! In short term,  Perovskite-based solar cell may boost the efficiency level of existing technology and in the long term. It may be a stand-alone technology with closer efficiency level to that of gallium arsenide but at a much lower cost. It may potentially be sprayed, ink-jet printed, dip-coated, etc. It is no wonder that Dr. Case commented, “the perovskite in solar application is the fastest increasing photovoltaic efficiency of any solar photovoltaic thin film material ever! In just a few years, it went from a lab efficiency of about 6% to well over 17%…the material is a very good solar absorber….bringing the material to 25% efficiency in a monolithic layer and 30%+ in a perovskite tandem layer….potentially the future replacement for silicon.” The perovskite thin-film solar cells, is currently being developed by Oxford PV (a spin-out from the University of Oxford in 2009-2010 to commercialize this technology, which has exclusively licensed the intellectual property developed by Professor Henry Snaith and his team of 20 scientists). Below, Professor Henry Snaith will embellish upon the development of this solar technology, in the video published on Jan. 10, 2014, “Perovskites: The Emergence of a New Era for Low-Cost, High-Efficiency Solar Cells“, below :

Henry J. Snaith is Professor of Physics in the Clarendon Laboratory at the University of Oxford and Fellow of the Royal Society. He has pioneered the field of perovskite solar cells and published hundreds of papers. He is founder and CSO of Oxford PV, which holds the largest perovskite patent portfolio worldwide and focuses on developing and commercializing perovskite PV technology. In this interview, he discusses the present status and future prospects of perovskite PV, in the video published on Nov. 11, 2018, “The Path to Perovskite on Silicon PV | Prof. Henry Snaith“, below:

Oxford PV plans on continuing to optimize this technology’s cell efficiency and accelerate the transfer of the technology into production. Furthermore, it aims to develop the range of substrates to which the cells can be applied. With its promising future, we, the solar enthusiasts and investors alike, should keep our eyes on Oxford PV in the coming years. In the next few years, we anticipate that Dr. Henry Snaith and his team of scientists will continue to tackle challenges in trap densities, doping densities, mobility, mechanisms for free carrier generations, etc., to further improve device performance. You will find that many in the solar industry share the optimism of Professor Henry Snaith and Dr. Christopher Case. In the video published on June 9, 2021, “Henry Snaith – The advent of Perovskite solar cells“, below: For those of you interested in more details about Perovskite-based solar cell technology, please refer to the two videos below:

1. Introducing Perovskite Solar Cells to Undergraduates:  

2. In the video published on Nov. 17, 2017, “Everything you ever wanted to know about perovskite“, below:

Keep in mind that Shockley-Queisser limit applies to silicon solar cell and not to perovskite solar cell. The Shockley-Queisser limit is calculated by examining the amount of electrical energy that is extracted per photon of incoming sunlight. For better understanding of Shockley-Queisser limit, please refer to the excerpt from wikipedia, in italics, below: In a traditional solid-state semiconductor such as silicon, a solar cell is made from two doped crystals, one an n-type semiconductor, which has extra free electrons, and the other a p-type semiconductor, which is lacking free electrons, referred to as “holes.” When initially placed in contact with each other, some of the electrons in the n-type portion will flow into the p-type to “fill in” the missing electrons. Eventually enough will flow across the boundary to equalize the Fermi levels of the two materials. The result is a region at the interface, the p-n junction, where charge carriers are depleted on each side of the interface. In silicon, this transfer of electrons produces a potential barrier of about 0.6 V to 0.7 V.^[6] When the material is placed in the sun, photons from the sunlight can be absorbed in the p-type side of the semiconductor, causing electrons in the valence band to be promoted in energy to the conduction band. This process is known as photoexcitation. As the name implies, electrons in the conduction band are free to move about the semiconductor. When a load is placed across the cell as a whole, these electrons will flow from the p-type side into the n-type side, lose energy while moving through the external circuit, and then go back into the p-type material where they can re-combine with the valence-band holes they left behind. In this way, sunlight creates an electric current.^[6] In physics, the Shockley–Queisser limit (also known as the detailed balance limit, Shockley Queisser Efficiency Limit or SQ Limit, or in physical terms the radiative efficiency limit) is the maximum theoretical efficiency of a solar cell using a single p-n junction to collect power from the cell where the only loss mechanism is radiative recombination in the solar cell. It was first calculated by William Shockley and Hans-Joachim Queisser at Shockley Semiconductor in 1961, giving a maximum efficiency of 30% at 1.1 eV.^[1] This first calculation used the 6000K black-body spectrum as an approximation to the solar spectrum. Subsequent calculations have used measured global solar spectra (AM1.5G) and included a back surface mirror which increases the maximum efficiency to 33.7% for a solar cell with a bandgap of 1.34 eV.^[2] The limit is one of the most fundamental to solar energy production with photovoltaic cells, and is considered to be one of the most important contributions in the field.^[3] The limit is that the maximum solar conversion efficiency is around 33.7% for a single p-n junction photovoltaic cell, assuming typical sunlight conditions (unconcentrated, AM 1.5 solar spectrum), and subject to other caveats and assumptions discussed below. This maximum occurs at a band gap of 1.34 eV.^[2] That is, of all the power contained in sunlight (about 1000 W/m²) falling on an ideal solar cell, only 33.7% of that could ever be turned into electricity (337 W/m²). The most popular solar cell material, silicon, has a less favorable band gap of 1.1 eV, resulting in a maximum efficiency of about 32%. Modern commercial mono-crystalline solar cells produce about 24% conversion efficiency, the losses due largely to practical concerns like reflection off the front of the cell and light blockage from the thin wires on the cell surface. The Shockley–Queisser limit only applies to conventional solar cells with a single p-n junction; solar cells with multiple layers can (and do) outperform this limit, and so can solar thermal and certain other solar energy systems. In the extreme limit, for a multi-junction solar cell with an infinite number of layers, the corresponding limit is 68.7% for normal sunlight,^[4] or 86.8% using concentrated sunlight.^[5] (See Solar cell efficiency.) Gathered, written, and posted by Windermere Sun-Susan Sun Nunamaker   More about the community at www.WindermereSun.com

Any comments, suggestions, concerns regarding this post will be welcomed at info.WindermereSun@gmail.com

We Need Fair Value of Solar

~Let’s Help One Another~

[mc4wp_form id=”12402″]

Please also get into the habit of checking at these sites below for more on solar energy topics:

www.sunisthefuture.net

www.kiva.org/team/sunisthefuture

www.facebook.com/sunisthefuture

www.pinterest.com/sunisthefuture

Share on Facebook

Dear Readers,

If you are in favor of renewable,  clean, or solar energy, please sign this petition for FIT/CLEAN Program, accessible at http://sunisthefuture.net/?page_id=1065 Thank you very much.

——————————————————————————————————————————————————————

Dear Solar Enthusiasts,

(Please click onred linksbelow)

This past week, U.S. imposed tariffs at a range of 31 to 250 percent on Chinese-made solar products to aid domestic (U.S.) manufacturers beset by foreign competition, but many critics believe that this decision may end up raising prices and hurting the U.S. renewable energy industry.  I personally have several issues or question with regard to this range of tariffs, to be addressed in this post.

FACTS

The purpose of imposing this range of tariffs, otherwise known as the preliminary anti-dumping duties, is because the U.S. Department of Commerce ruled that Chinese manufacturers sold solar panels in the U.S. at prices below the cost of production.  This decision is meant to provide a boost to the U.S. solar manufacturing industry.  In the preliminary determination, the U.S. Department of Commerce (DOC) set duties at 31.14 % for Trina, 31.18 % for 59 Chinese solar manufacturers (including Yingli Green Energy, LDK Solar, Canadian Solar, Hanwha Solar One, JA Solar Holding, and Jinko Solar) that chose to participate in the investigation, 31.22 % for Suntech, and 250 % for those Chinese solar manufacturers that chose not to participate at this investigation.  The tariffs will be retroactive and be applied to panels that were shipped from as far back as about the middle of February, 2012.  A final determination may still be made, so the tariff rates may be adjusted in the future. But the tariff rates resulting from this ruling  were much higher than many had anticipated.  This was the second of two duties/tariffs set by the DOC that stemmed from a trade complaint filed by SolarWorld’s American subsidiary.  DOC’s final determinations are expected to be made for both tariffs in late July of 2012 and its announcement may reach the public as late as September of 2012.

Previously, in March, the DOC announced a preliminary determination that set relatively modest countervailing duties that essentially measure the level of subsidies and benefits coming from the Chinese government to Chinese crystalline silicon panel manufacturers: 2.9% for Suntech, 4.73% for Trina, 3.59% to all others.  But now, added by the second duty/tariff mentioned in the paragraph above, Chinese solar panels will be much more expensive.  The ruling could add about $0.30 per watt to the price of a panel.   So, Chinese companies are expected to set up workarounds like tolling (tolling is expected to add only about $0.06 to $0.08 per watt) in which they send panels through another country, or even set up remote manufacturing facilities outside their country.

Below, I have a video clip from Suntech Power, to help better understand how Suntech PV cells and modules are made, below:

If you are as ignorant as I was about the international trade policy, this will help to clarify the situation: To search for better understanding of the DNA of  history of U.S. Tariffs, I obtained help from Wikipedia, and found that tariffs were the largest source of U.S. federal revenue until the Federal income tax began after 1913. The history of U.S. tariffs went as far back as Tariff of 1790, established under the guidance of Alexander Hamilton;he calculated that the U.S. required sufficient revenue in order to maintain $3  million per year in operating cost and repayment for the $75 million  foreign and domestic debt.  Therefore, Hamilton proposed an increase in the average tariff rate of 5% to between 7 and 10%, with addition of numerous items, and the passage of an excise tax.  Congress refused to pass the excise tax, but James Madison successfully steered the tariff increases through the legislature.  In light of our current national debt rate and the relationship between President and Congress, one is amazed at how often history repeats itself.  I am no longer surprised at the dramatic increase of tariffs (be it solar or otherwise) if I simply remember how much our current national debt rate is.   But one does need to ask if similar rate of increase in tariff is also occurring in other industries.

Secondly, with the help from Encyclopedia Britannica and Wikipedia, essentially, in international trade ( if company a comes  from country A and company b comes from country B), it is all right for company a to sell at below the cost of production in country A (which often happens when there is an over supply of certain products, as what would happen during sales and clearances) , but it is not all right for company a to sell at below the cost of production in country B (henceforth the existence of tariffs) in order to protect merchants/manufacturers of similar products from country B.  So, the existence of tariffs would benefit the local manufacturers but not necessarily local consumers.

CONCERNS/QUESTIONS/SUGEESTIONS

I have several concerns/issues/questions regarding this decision/tariff range:

1. The range from about  31% to 250% seems rather wide.  The high end (250%) reserved for Chinese solar manufacturers that did not participate in this investigation: will this unusually high tariff rate result in preventing other Chinese manufacturers from ever considering any future sells to U.S. while providing special protection for Chinese manufacturers that have already participated in the current  investigation with U.S. ?
2. The fact that this tariff will be retroactive as far back as February of 2012:  will this decrease the desirability/amount of future international trades with U.S. from other nations ?
3. How are these rates determined ?  I had a tough time obtaining the information regarding how these rates were set due to its proprietary information status.  Is it possible for the decision for these rates to be more transparent and be available to public?
4. Assuming we are all cooperative human beings trying to optimize our earthly resources, will it be possible for the Chinese manufacturers to work out deals with the US manufacturers by transporting the solar cells (which takes up most of the manufacturing cost of any solar module) to U.S. to be assembled into its modular forms in U.S. plants so to help reduce the tariffs.  In so doing, this will also help to reduce the transporting cost of the frames and various other components of the solar modules. U.S., in this scenario,  will benefit from increased local jobs for assembling solar panels in U.S.
5. In light of our globalized economy and existence of tolling (mentioned above under FACTS), it is questionable how much revenue will truly be generated from this tariff.
6. Will this tariff  increase the cost for American consumers and reduce the competitiveness of U.S. solar industry  rather than simply boosting U.S. solar manufacturing industry in the future ?

I hope U.S. Department of Commerce will carefully weigh all of these issues before final determination later this year.  Much remains to be seen.  I welcome any of your questions/discussions/comments/concerns/suggestions here at Sun Is The Future (of http://sunisthefuture.net) via sunisthefuture@gmail.com

~have a bright and sunny day~

Gathered, written, and posted by sunisthefuture-Susan Sun Nunamaker

Any comments and suggestions are welcomed at sunisthefuture@gmail.com

Please also get into the habit of checking at these sites below for more on solar energy topics:

www.sunisthefuture.net

www.youtube.com/user/sunisthefuture

www.kiva.org/team/sunisthefuture

www.facebook.com/sunisthefuture

www.pinterest.com/sunisthefuture

Google+

Share on Facebook