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Physicists at the University of Warwick have today, Thursday 19th April 2018, published new research in the fournal Science today 19th April 2018 (via the Journal’s First Release pages) that could literally squeeze more power out of solar cells by physically deforming each of the crystals in the semiconductors used by photovoltaic cells.

The paper entitled the “Flexo-Photovoltaic Effect” was written by Professor Marin Alexe, Ming-Min Yang, and Dong Jik Kim who are all based in the University of Warwick’s Department of Physics.

The Warwick researchers looked at the physical constraints on the current design of most commercial solar cells which place an absolute limit on their efficiency. Most commercial solar cells are formed of two layers creating at their boundary a junction between two kinds of semiconductors, p-type with positive charge carriers (holes which can be filled by electrons) and n-type with negative charge carriers (electrons).

Trapping light with an optical version of a whispering gallery, researchers at the National Institute of Standards and Technology (NIST) have developed a nanoscale coating for solar cells that enables them to absorb about 20 percent more sunlight than uncoated devices. The coating, applied with a technique that could be incorporated into manufacturing, opens a new path for developing low-cost, high-efficiency solar cells with abundant, renewable and environmentally friendly materials.

The coating consists of thousands of tiny glass beads, only about one-hundredth the width of a human hair. When sunlight hits the coating, the light waves are steered around the nanoscale bead, similar to the way sound waves travel around a curved wall such as the dome in St. Paul’s Cathedral in London. At such curved structures, known as acoustic whispering galleries, a person standing near one part of the wall easily hears a faint sound originating at any other part of the wall.

Whispering galleries for light were developed about a decade ago, but researchers have only recently explored their use in solar-cell coatings. In the experimental set up devised by a team including Dongheon Ha of NIST and the University of Maryland’s NanoCenter, the light captured by the nanoresonator coating eventually leaks out and is absorbed by an underlying solar cell made of gallium arsenide.

Researchers proposed implementing the residential energy scheduling algorithm by training three action dependent heuristic dynamic programming (ADHDP) networks, each one based on a weather type of sunny, partly cloudy, or cloudy. ADHDP networks are considered ‘smart,’ as their response can change based on different conditions.

“In the future, we expect to have various types of power supplies to every household including the grid, windmills, solar panels and biogenerators. The issues here are the varying nature of these power sources, which do not generate electricity at a stable rate,” said Derong Liu, a professor with the School of Automation at the Guangdong University of Technology in China and an author on the paper. “For example, power generated from windmills and solar panels depends on the weather, and they vary a lot compared to the more stable power supplied by the grid. In order to improve these power sources, we need much smarter algorithms in managing/scheduling them.”

The details were published on the January 10th issue of IEEE/CAA Journal of Automatica Sinica, a joint bimonthly publication of the IEEE and the Chinese Association of Automation.

A simultaneous imaging and energy harvesting sensor is in the news. Samuel Moore at IEEE Spectrum informed readers that a team of four from University of Michigan published their paper describing what they achieved. They built a prototype sensor, and what it does—-think of a future camera that just about watches you non-stop—is described in the journal, IEEE Electron Device Letters.

The article is titled “Simultaneous Imaging and Energy Harvesting in CMOS Image Sensor Pixels.” The four authors are from University of Michigan: Sung-Yun Park, Kyuseok Lee, Hyunsoo Song and Euisik Yoon.

Their technology “puts the equivalent of a solar cell under each pixel,” said IEEE Spectrum.

Continue reading “This imaging sensor is powered by sunlight” »

Mechanical engineers at the University of California, Riverside, have reported success in using inexpensive materials to produce thermoelectric devices that transform low-level waste heat into electricity.

Their advance could enable a wide variety of commercial applications. For example, integrating thermoelectric generating devices into computer chips could enable the heat they produce to provide a power source. Waste heat from automobile engines could run a car’s electronics and provide cooling. Photovoltaic solar cells could be made more efficient by harnessing the heat from sunlight striking them to generate more electricity.

Also, using the same basic technology, economical thermoelectric refrigerators could be produced that would be more energy efficient and with fewer moving parts than refrigerators that use compressors and coolant. Current thermoelectric refrigerators are expensive and relatively inefficient. In essence, they operate in reverse of thermoelectric generators, with an electric current applied to generate a temperature gradient that could be used in cooling.

Continue reading “Harnessing ‘Rashba spin-Seebeck effect’ phenomenon will enable commercial devices to turn waste heat into electricity” »

A new sodium-ion battery chemistry that shows superior performance to existing state-of-the-art sodium-based batteries could be the catalyst to enabling mass-production of the emerging technology for large-scale energy storage, such as in applications including storing solar power for industrial sites.

Despite sodium’s appeal as a low-cost, abundant and environmentally friendly building block for energy storage, it is a relatively new entrant in the field of battery technology research and development.

A key issue for sodium-ion batteries is that many of the active materials used in their chemistry are sensitive to air—exposure to even a few molecules of air can degrade the material and reduce battery performance.

Researchers have taken a step toward manufacturing solar cells from lead-free perovskites. High-quality films based on double perovskites, which show promising photovoltaic properties, have been developed in collaboration between Linköping University, Sweden, and Nanyang Technological University in Singapore.

Research groups around the world are pursuing the potential of perovskites as one of the most promising materials for the development of cheap, environmentally friendly and efficient solar cells. In just a few years, the power conversion efficiency has increased from a few percent to over 22 percent. The perovskites currently available for use in solar cells, however, contain lead, and Feng Gao, senior lecturer at LiU, was appointed in the autumn of 2017 as Wallenberg Academy Fellow to develop lead-free double perovskites, in which a monovalent metal and a trivalent metal replace the divalent lead.

In the laboratory at the Division of Biomolecular and Organic Electronics, LiU, postdoc researchers Weihua Ning and Feng Wang have successfully manufactured single-layer thin films of densely packed crystals of double perovskites. The films are of extremely high quality and can be used as the active layer in solar cells, in which sunlight is absorbed and charge carriers created.

Continue reading “Double perovskites in environmentally friendly solar cells” »

A report out from the Australian Renewable Energy Agency (ARENA) this month published responses from industry stakeholders on the viability of a concentrated solar thermal (CST) energy market in Australia: Paving the way for concentrated solar thermal in Australia.

Only 5 gigawatts (GW) of CST is deployed globally so far, with remarkable cost reductions for a technology so “young.” Submissions noted that when today’s 300 GW of PV had only 5 GW of deployed capacity in 2004, its LCOE was ten times that of CST.

CST’s dispatchable solar could play a pivotal role in Australia with its need for energy that can meet obligations for both emissions reductions and reliability, because with its ability to store its solar energy in molten salts for delivery later, CST can offer a stable and predictable supply of solar energy at any time of day or night.

Continue reading “Path to a booming Australian solar thermal energy market” »

Saudi engineers whip up a simulated sandstorm to test a solar panel’s durability at a research lab, the heart of the oil-rich kingdom’s multibillion dollar quest to be a renewable energy powerhouse.

The world’s top exporter of crude seems an unlikely champion of clean energy, but the government lab in Al Uyayna, a sun-drenched village near Riyadh, is leading the country’s efforts for solar power as it seeks to diversify.

A dazzling spotlight was shone on those ambitions last week when Crown Prince Mohammed bin Salman unveiled plans to develop the globe’s biggest solar power project for $200 billion in partnership with Japan’s SoftBank group.