New Solar System Produces 50 Percent More Energy

A concentrating photovoltaic system (CPV) with embedded microtracking can produce over 50 percent more energy per day than standard silicon solar cells in a head-to-head competition, according to a team of engineers who field tested a prototype unit over two sunny days last fall.

Solar cells used to be expensive, but now they’re getting really cheap,” said Chris Giebink, Charles K. Etner Assistant Professor of Electrical Engineering, Penn State. “As a result, the solar cell is no longer the dominant cost of the energy it produces. The majority of the cost increasingly lies in everything else — the inverter, installation labor, permitting fees, etc. — all the stuff we used to neglect.

This changing economic landscape has put a premium on high efficiency. In contrast to silicon solar panels, which currently dominate the market at 15 to 20 percent efficiency, concentrating photovoltaics focus sunlight onto smaller, but much more efficient solar cells like those used on satellites, to enable overall efficiencies of 35 to 40 percent. Current CPV systems are large — the size of billboards — and have to rotate to track the sun during the day. These systems work well in open fields with abundant space and lots of direct sun.

What we’re trying to do is create a high-efficiency CPV system in the form factor of a traditional silicon solar panel,” said Giebink.


Nano Solar Cells

A humming laboratory is birthing tiny solar cells – the first such devices created on campus – as Kennesaw State (KSU) in Georgia researchers strive to develop better photovoltaic technologies. Sandip Das, assistant professor of electrical engineering in the Southern Polytechnic College of Engineering and Engineering Technology, along with a team of three undergraduate research assistants, has recently fabricated the delicate solar cells, which are about 100 times thinner than a human hair. The future of solar power generation is in these flexible solar cells, Das said.  He and his research team are investigating various nano-materials to fabricate the third-generation solar cells. The researchers hope to develop a superior photovoltaic technology that produces cheaper and more efficient solar cells.

3rd generation Solar Cells

The most fascinating part of doing this research is the enormous potential that this new technology offers, such as integrating flexible solar cells on wearable electronics, backpacks and self-charging cell phones and electricity-generating layers on windows, especially on skyscrapers, and solar power’s ability to supply a large amount of clean, renewable and cheap energy for the future,” said David Danilchuk, an electrical engineering major who is an undergraduate research assistant on the project.

In the laboratory, the research team fabricated the solar cells’ multiple nano-structured layers using a unique manufacturing process. Specialty instruments, like electron microscopes, as well as X-ray spectroscopy techniques and precision electronic measurement systems, enable the research team to investigate and better understand the cells’ behavior.

Baker Nour, an electrical engineering student and member of the research team, explained that the fabrication process developed by the team can produce these solar cells on plastic substrates to create flexible solar cells — one of the most advanced ideas in solar technology today.

In practice, these flexible solar panels can be beneficial after catastrophic storms. Disaster relief personnel could transport rolled-up solar panels to produce portable power on site, Das explained. Commercial building developers also are eyeing smart building applications, like transparent solar panels for windows, so skyscrapers can generate solar power and be more energy efficient.  The most promising materials systems for future generation solar cells, according to Das, are the materials that his research team applies in their fabrication – an ultra-thin hybrid Perovskite noncrystalline film. Rather than using expensive silicon, they fabricate their solar cells on cheap glass substrates like those in windows and beverage bottles. The team plans to explore the fabrication process so they can develop solar cells on flexible plastics or metal foils, without requiring expensive materials, million-dollar equipment or scientific-grade clean rooms.

For the past 20 years, efficiency of silicon solar cells could not be improved much after substantial research efforts globally,” Das said.  He explained that silicon is not a good light absorber, and new technologies are needed to create high-efficiency cells at a lower cost. The new bandgap-engineered Perovskite crystals, which his team is investigating, can absorb a wider spectrum of sunlight compared to silicon, on a film that is 200 times thinner than silicon cells.



Solar Cells: How To Boost Perovkite Efficiency Up To 31%

Scientists from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a possible secret to dramatically boosting the efficiency of perovskite solar cells hidden in the nanoscale peaks and valleys of the crystalline material.

Solar cells made from compounds that have the crystal structure of the mineral perovskite have captured scientists’ imaginations. They’re inexpensive and easy to fabricate, like organic solar cells. Even more intriguing, the efficiency at which perovskite solar cells convert photons to electricity has increased more rapidly than any other material to date, starting at three percent in 2009—when researchers first began exploring the material’s photovoltaic capabilities—to 22 percent today. This is in the ballpark of the efficiency of silicon solar cells.

Now, as reported online July 4 in the journal Nature Energy, a team of scientists from the Molecular Foundry and the Joint Center for Artificial Photosynthesis, both at Berkeley Lab, found a surprising characteristic of a perovskite solar cell that could be exploited for even higher efficiencies, possibly up to 31 percent.

Using photoconductive atomic force microscopy, the scientists mapped two properties on the active layer of the solar cell that relate to its photovoltaic efficiency. The maps revealed a bumpy surface composed of grains about 200 nanometers in length, and each grain has multi-angled facets like the faces of a gemstone. Unexpectedly, the scientists discovered a huge difference in energy conversion efficiency between facets on individual grains. They found poorly performing facets adjacent to highly efficient facets, with some facets approaching the material’s theoretical energy conversion limit of 31 percent. The scientists say these top-performing facets could hold the secret to highly efficient solar cells, although more research is needed.

perovskite solar panel

“If the material can be synthesized so that only very efficient facets develop, then we could see a big jump in the efficiency of perovskite solar cells, possibly approaching 31 percent,” says Sibel Leblebici, a postdoctoral researcher at the Molecular Foundry.

Leblebici works in the lab of Alexander Weber-Bargioni, who is a corresponding author of the paper that describes this research. Ian Sharp, also a corresponding author, is a Berkeley Lab scientist at the Joint Center for Artificial Photosynthesis. Other Berkeley Lab scientists who contributed include Linn Leppert, Francesca Toma, and Jeff Neaton, the director of the Molecular Foundry.


Solar Cell Converts 34,5% Of The Sunlight To Electricity

A new solar cell configuration developed by engineers at the University of New South Wales (UNSW) in Australia, has pushed sunlight-to-electricity conversion efficiency to 34.5% – establishing a new world record for unfocused sunlight and nudging closer to the theoretical limits for such a device. The record was set by Dr Mark Keevers and Professor Martin Green, Senior Research Fellow and Director, respectively, of UNSW’s Australian Centre for Advanced Photovoltaics, using a 28-cm2 four-junction mini-module – embedded in a prism – that extracts the maximum energy from sunlight. It does this by splitting the incoming rays into four bands, using a hybrid four-junction receiver to squeeze even more electricity from each beam of sunlight. The new UNSW result, confirmed by the US National Renewable Energy Laboratory, is almost 44% better than the previous record – made by Alta Devices of the USA, which reached 24% efficiency, but over a larger surface area of 800-cm2.


This encouraging result shows that there are still advances to come in photovoltaics research to make solar cells even more efficient,” said Keevers. “Extracting more energy from every beam of sunlight is critical to reducing the cost of electricity generated by solar cells as it lowers the investment needed, and delivering payback faster.”

The result was obtained by the same UNSW team that set a world record in 2014, achieving an electricity conversion rate of over 40% by using mirrors to concentrate the light – a technique known as CPV (concentrator photovoltaics) – and then similarly splitting out various wavelengths. The new result, however, was achieved using normal sunlight with no concentrators.


How To Increase Photovoltaic Efficiency

Researchers from the The Center for Integrated Nanotechnologies at the Los Alamos National Laboratory (LANL) have built tiny “match-headwires that act as built-in light concentrators, enhancing solar cell efficiency.

Crystal growth on a nano/microscale level results in the formation of “match-head”-like, three-dimensional structures that enhance light absorption and photovoltaic efficiency. Match-head semiconductor nanowires focus incident light for greater overall efficiency. The match heads are naturally formed during the wire-growth process, which can be applied to various materials and structures for photonic and optoelectronic devices. This is the first large structure grown on a nanowire tip and it creates a completely new architecture for harnessing energy.

match-head(Left) Silicon wires with match heads and (right) light absorption profile of a single match-head wire at 587 nm absorption

Enhanced light absorption and efficient, photogenerated carrier collection are essential characteristics of highly efficient solar cells. Nanowires with embedded radial junctions are promising building blocks for highly efficient photovoltaics because of their ability to achieve these two characteristics. The new technology in this highlight provides a novel method for enhancing optical absorption and photovoltaic efficiency with crystal growth. Controlled silicon crystal growth on the tops of silicon wires creates a match-head structure. The match head acts as a light concentrator. Light absorptance was increased by 36% and photovoltaic efficiency was increased by 20%. Because the match-head crystal is naturally grown and minimizes surface energy, this technique is applicable for a wide range of materials and device architectures to boost performance. The ability to control the shape of the nanostructure is essential for manufacturing next-generation semiconductor devices, such as photodetectors and light emitters.


Solar Roads Power Houses, Lights, Vehicles

For the first time ever, roads can produce electricity, while preserving their full capacity to bear vehicle traffic. The french company Colas, a world leader in transport infrastructure, in a partnership with the Institut national de l’énergie solaire (Ines), has developed Wattway, a new concept of photovoltaic road surfacing that is now market-ready. This innovation is a major technological breakthrough, a building block for cutting-edge projects involving intelligent roads and Smart Cities.

solar road
Extra thin and extremely sturdy, Wattway photovoltaic panels provide excellent grip and durable performance. They are directly applied to existing roads, highways, bike paths, parking areas, etc., without any civil engineering work and can safely bear vehicle traffic of all types, while producing electricity


To supply an average single home (not including heating), only 20 m² of Wattway are needed.

With 1km-long section of Wattway panels, it is possible to power the street lights for a town of 5,000 inhabitants, said Colas. The system is also seen as a first step in creating ‘intelligent roads’ that can manage traffic, gather maintenance information and even charge electric vehicles.

The photovoltaic road surfacing concept is said to be the first of its kind in the world. Wattway panels comprise photovoltaic cells embedded in a multilayer substrate. These cells collect solar energy via a very thin film of polycrystalline silicon that enables the production of electricity. On the underside of the panels, there is a connection to a lateral module containing the electrical safety components.

Wattway is able to provide power to street lights, signs, tramways, as well as housing, offices and so on, said the company.

Protected by two patents, the cutting-edge technique is a major breakthrough, as it provides the road with a new function: producing clean, renewable energy locally, in addition to a road’s conventional use.


How To Make Solar Energy Conversion More Efficient

When it comes to installing solar cells, labor cost and the cost of the land to house them constitute the bulk of the expense.  The solar cells – made often of silicon or cadmium telluride – rarely cost more than 20 percent of the total costSolar energy could be made cheaper if less land had to be purchased to accommodate solar panels, best achieved if each solar cell could be coaxed to generate more power.

A huge gain in this direction has now been made by a team of chemists at the University of California, Riverside (UCR) that has found an ingenious way to make solar energy conversion more efficientThe researchers report in Nano Letters that by combining inorganic semiconductor nanocrystals with organic molecules, they have succeeded in “upconvertingphotons in the visible and near-infrared regions of the solar spectrum.


Solar-panels UCRChemists at the University of California, Riverside have found an ingenious way to make solar energy conversion more efficient

The infrared region of the solar spectrum passes right through the photovoltaic materials that make up today’s solar cells,” explained Christopher Bardeen, a professor of chemistry. The research was a collaborative effort between him and Ming Lee Tang, an assistant professor of chemistry. “This is energy lost, no matter how good your solar cell.  The hybrid material we have come up with first captures two infrared photons that would normally pass right through a solar cell without being converted to electricity, then adds their energies together to make one higher energy photon.  This upconverted photon is readily absorbed by photovoltaic cells, generating electricity from light that normally would be wasted.”


Solar Film: How To Increase The Absorption Of Sunlight

A biological structure in mammalian eyes has inspired a team headed by Silke Christiansen to design an inorganic counterpart for use in solar cells. With the help of conventional semiconductor processes, they etched micron-sized vertical funnels shoulder-to-shoulder in a silicon substrate. Using mathematical models and experiments, they tested how these kind of funnel arrays collect incident light and conduct it to the active layer of a silicon solar cell. Their result: this arrangement of funnels increases photo absorption by about 65% in a thin-film solar cell fitted with such an array and is reflected in considerably increased solar cell efficiency, among other improved parameters. This closely packed arrangement of cones has now inspired the team headed by Prof. Silke Christiansen to replicate something similar in silicon as a surface for solar cells and investigate its suitability for collecting and conducting light. Christiansen heads the Institute for Nanoarchitectures for Energy Conversion at the Helmholtz-Zentrum Berlin (HZB) and a research team at the Max Planck Institute for the Science of Light (MPL) – Germany..

solar funnelThe simulation shows how the concentration of light (red = high concentration, yellow= low concentration) rises in the funnels with declining diameter of the lower end of the funnel
We’ve shown in this work that the light funnels absorbs considerably more light than other optical architectures tested over the last while”, says Sebastian Schmitt, one of the two first authors of the publication that has appeared in journal Nature Scientific Reports.


Solar Plant produces twice more Than Nuclear Power Plant

A solar energy project in the Tunisian Sahara aims to generate enough clean energy by 2018 to power two million European homes. Called the TuNur project; developers, including renewable investment company Low Carbon and solar developer Nur Energie, say the site will produce twice as much energy as the average nuclear power plant. But instead of using typical photovoltaic cells that only generate power during the day; they’re using Concentrated Solar Power. Using a vast array of mirrors to concentrate and  reflect the intense Saharan sun to a central tower, water or molten salt is heated to over 500 degrees Celsius. The steamced powers a turbine which in turn generates electricity. This, says Nur Energie‘s CEO Kevin Sara, means the plant will produce electricity even when the sun is down.


solar power plant

 “The technology that you can deploy in the desert is baseload renewable power; that means you can actually replace fossil fuel power plants because we can generate 24-7 using solar power,” says Kevin Sara, CEO of Nur Energie. Transmission lines will take the electricity to the Tunisian coast where a dedicated undersea cable will connect it to the European grid via a hub in northern Italy. Over ten millions euros has already gone into identifying the best location in the Tunisian Sahara to harness the intense solar radiation. “It’s quite large; it’s 10,000 hectares – a hundred square kilometres. But there’s nothing there, it’s just sand and a few bushes.

With energy security a big concern, Sara says the project has the potential to help end Europe’s reliance on fossil fuels using ‘desert power‘. “We believe that this is really opening a new energy corridor. This could be the first of many projects, and we could gradually de-carbonise the European grid using desert power, using this solar energy with storage from the Sahara desert and linked to Europe with high-voltage DC cables which are very, very low in their losses.” Sara added.
Tunisia is seeking to bolster its stability following the 2011 uprising, with lack of jobs and growth contributing to the unrest. The team behind the TuNur project hope the Saharan sunshine will be a shining light not only for renewable energy, but for the future of Tunisia.


How To Tap The Sun’s Energy Through Heat

A new approach to harvesting solar energy, developed by MIT researchers, could improve efficiency by using sunlight to heat a high-temperature material whose infrared radiation would then be collected by a conventional photovoltaic cell. This technique could also make it easier to store the energy for later use, the researchers say. In this case, adding the extra step improves performance, because it makes it possible to take advantage of wavelengths of light that ordinarily go to waste.

A conventional silicon-based solar celldoesn’t take advantage of all the photons,” explains associate professor of mechanical engineering Evelyn Wang,. That’s because converting the energy of a photon into electricity requires that the photon’s energy level match that of a characteristic of the photovoltaic (PV) material called a bandgap. Silicon’s bandgap responds to many wavelengths of light, but misses many others. This basic concept has been explored for several years, since in theory such solar thermophotovoltaic (STPV) systems could provide a way to circumvent a theoretical limit on the energy-conversion efficiency of semiconductor-based photovoltaic devices. That limit, called the Shockley-Queisser limit, imposes a cap of 33.7 percent on such efficiency, but Wang says that with TPV systems, “the efficiency would be significantly higher — it could ideally be over 80 percent.
nanophotonic solar photovoltaicNanophotonic solar thermophotovoltaic device

Zhuomin Zhang, a professor of mechanical engineering at the Georgia Institute of Technology who was not involved in this research, says, “This work is a breakthrough in solar thermophotovoltaics, which in principle may achieve higher efficiency than conventional solar cells because STPV can take advantage of the whole solar spectrum. … This achievement paves the way for rapidly boosting the STPV efficiency.

The process is described in a paper published this week in the journal Nature Nanotechnology.

Low Cost, Highly Efficient Solar Cell

A group of researchers led by Hendrik Bolink of the Institut de Ciència Molecular (ICMol) of the Scientific Park of the University of Valencia – Spain – has developed a thin film low cost photovoltaic device with high power conversion efficiency. The results of this work, done in collaboration with researchers of École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, were published yesterday in the scientific magazine Nature Photonics.
The solar cell developed by the researchers of the ICMol consists of a thin perovskite film sandwiched in between two very thin organic semiconductors. The total thickness of the device is less than half a micrometer, less than a millions’ part of a meter. The hybrid organic-inorganic perovskite material can be prepared easily and at low cost. Hendrik Bolink explains that these devices were prepared with low temperature processes similar to those used in the printing industry which allows the use of plastic substrates such that flexible devices can be prepared.

Most of the solar cells that convert sun light into electricity are based on crystalline silicon, en expensive material, whereas the remainder uses polycrystalline thin film cells, mostly cadmium telluride/cadmium sulfide. These thin film cells are cheaper to produce yet are based on rare and rather toxic elements.

The demonstration of high efficiency in thin film solar cells based on abundantly available and cheap materials like as used in these perovskite based solar cells, allows for an increasing share of solar energy in the mix of renewable resources” said Dr. Bolink.

Novel Solar Cell Twice More Efficient

Nearly doubling the efficiency of a breakthrough photovoltaic cell they created last year, UCLA researchers have developed a two-layer, see-through solar film that could be placed on windows, sunroofs, smartphone displays and other surfaces to harvest energy from the sun. Researchers led by Yang Yang, the Carol and Lawrence E. Tannas, Jr., Professor of Engineering at the UCLA Henry Samueli School of Engineering and Applied Science, said the new cells could serve as a power-generating layer on windows and smartphone displays without compromising users’ ability to see through the surface. The cells can be produced so that they appear light gray, green or brown, and so can blend with the color and design features of buildings and surfaces.
The new device is composed of two thin polymer solar cells that collect sunlight and convert it to power. It’s more efficient than previous devices, the researchers say, because its two cells absorb more light than single-layer solar devices, because it uses light from a wider portion of the solar spectrum, and because it incorporates a layer of novel materials between the two cells to reduce energy loss.
transparent SolarCell
Using two solar cells with the new interfacial materials in between produces close to two times the energy we originally observed,” said Yang, who is also director of the Nano Renewable Energy Center at the California NanoSystems Institute at UCLA. “We anticipate this device will offer new directions for solar cells, including the creation of solar windows on homes and office buildings.”