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Industry Progress

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Secret DC Grid Has Been Powering Parts of San Francisco Since 1879

DC electrical grids never really caught on for widespread public utility use. Their limited distribution range (a result of their late 1800s technology) couldn’t compete with AC’s transmission abilities. But one DC grid, located in San Francisco, has been operating since 1879, three years before Thomas Edison opened his New York DC power plant. In an article posted on the IEEE Spectrum web site, a 250-volt DC system coexists with AC lines, flowing through underground and overhead cables across the city. Such are the needs of some of its customers that PG&E (Pacific Gas and Electric), the local utility, has found it necessary to keep the system running.

One of the primary uses for DC power is elevator motors, dating from before 1930, that are still in use. These “winding drum” motors, outlawed after 1940 for safety reasons, were grandfathered in. They persist due to the enormous cost of replacing them with new elevator systems.

Due to technical issues that have arisen over the decades, mostly due to the aging of the equipment, PG&E has divided the DC grid into very small “islanded” sections, each serving about 7 to 10 customers. Instead of sending DC current over a separate grid throughout the city, the company now rectifies AC power nearby before sending it on to its destination.

Perhaps SF’s DC grid will stay in operation long enough to see a transition to a modern Direct Current grid, such as those operating in many parts of Europe. Transmission issues have been solved, meaning high voltage DC (HVDC) can be used to more efficiently power homes and businesses.

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Infrared Silicon Cells May Vastly Improve Solar Capacity

Scientists in Spain have announced the development of silicon photovoltaic cells capable of converting the sun’s infrared rays to electrical energy, opening the possibility of increasing PV efficiency. In an article on Nanowerk News, researchers from the Universitat Politècnica de València, the Spanish National Research Council, the Universitat Politècnica de Catalunya-Barcelona Tech, and the Universidad Rovira i Virgili de Tarragona made the joint announcement.

According to the Universitat Politècnica de Catalunya’s Moisés Garín, the cells trap infrared light and spins it until it is turned into electricity.

Infrared light makes up approximately 53 percent of the solar spectrum, and is normally experienced as heat. However, it cannot currently be used by PV to create electricity. Visible light, which typically powers PV cells, constitutes 44 percent, and ultraviolet 3 percent. An infrared absorbing cell, therefore, could theoretically double solar’s efficiency.

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Nextek’s 380 Volt DC Ballasts Approved by UL and CUL

Nextek Power Systems Inc. has received authorization to apply the UL mark on our 380 VDC ballast. The 380 VDC ballast is a 6-lamp ballast for use in both new and retrofit installations, making it perfect for highbay applications. It comes with three light level controls (33%, 67%,100%), and has an efficiency rating of > 97%. The 24VDC supply to load is isolated for 380VDC.

UL (Underwriters Laboratories) is an independent safety science company that tests and evaluates equipment to determine its compliance with UL safety standards. The awarding of the UL designation is respected around the world as a benchmark of product safety.

For more information on Nextek products, please visit our web site.

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Going Solar? There’s an App for That

Getting the best performance from solar panels is critical to maximizing energy usage efficiency. Xylem, a water technology company, has introduced a free app for the iPhone that helps users adjust the placement and orientation of their panels. The app is called XyDial. It enables users to locate, configure and adjust a solar panel in real-time, finding the ideal position that will receive the most sunlight and maximize power output

The app helps homeowners and installers, but Xylem created it primarily to support rural farming—which explains why a water tech company got involved in solar panel placement. The company has an Essence of Life initiative—as part of the first phasethey have developed a stepping pump that enables farmers to irrigate their crops more efficiently and effectively.

XyDial works by selecting where shadows and objects are in relation to the panel, and adjusts for any buildings or trees that may obstruct the sun’s arc. It uses some of iPhone’s built-in capabilities, such as the digital compass and gyroscope, which helps the app determine the optimal alignment relative to the sun’s arc for a particular location and date range.

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Best Buy and Home Depot Will Make Solar Panels Available in Their Stores

In the first efforts to make solar panels available in retail chain stores, Best Buy and Home Depot have announced agreements with California-based solar panel manufacturer SolarCity. The deals reflect the continuing drop in the pricing of solar energy systems, and increased public interest. According to a SolarCity survey, approximately 62 percent of US homeowners are interested in using solar panels, but fewer than 500,000 homes have photovoltaic panels on their roofs.

The main reason for the lack of commitment is believed to be the high upfront cost of installing solar. The deals with Best Buy and Home Depot include having store personnel walk customers through the process of installation and its eventual return on investment.

SolarCity, whose chairman is Tesla Motors CEO Elon Musk, will be able to sell its panels nationwide through the chain distributors.

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Energy Saving 2-D LEDs Developed by University of Washington

University of Washington scientists have developed a three-atom thick LED that can be used in electronic devices, potentially saving power loss through heat. The new LEDs are ten to twenty times thinner than conventional LEDs used in consumer products. Xiaodong Xu, a UW assistant professor in materials science and engineering and in physics, and grad student Jason Ross reported their findings in an online paper in Nature Nanotechnology on March 9.

The UW’s LED is made from flat sheets of the molecular semiconductor known as tungsten diselenide, a member of a group of two-dimensional materials that have been recently identified as the thinnest-known semiconductors.

In addition to light-emitting applications, this technology could use light as interconnects to run nano-scale computer chips instead of standard devices that operate off the movement of electrons, or electricity.

“These are 10,000 times smaller than the thickness of a human hair, yet the light they emit can be seen by standard measurement equipment,” Ross said. “This is a huge leap of miniaturization of technology, and because it’s a semiconductor, you can do almost everything with it that is possible with existing, three-dimensional silicon technologies.”

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Germany Shows Future of Electric Cars with DC-Based Charging Station

Germany is one of the nations firmly committed to a renewable energy future. Already more than 20 percent of the nation’s power is produced from solar and other renewable sources. Being able to efficiently utilize those sources is part of the issues that must be addressed. According to an article on automotiveworld.com, the country has more than 2,000 electric car charging spots. At the largest, at Fraunhofer Institute Center Stuttgart IZS –up to 30 electric vehicles at a time can re-charge at AC charge spots in the campus parking garage. There is also one DC fast charging spot that has a charging capacity of up to 50 kilowatts and can fully charge a car’s battery in just 20 minutes.

To get that kind of simultaneous power output requires state-of-the-art smart grid technology and load management. Daimler AG and the Institute for Human Factors and Technology Management at the University of Stuttgart, IAO scientists are developing both the charging infrastructure and the energy management in a project called charge@work. Their aim is to design a micro smart grid (MSG) capable of supplying the EV fleet with electricity produced exclusively from renewable sources. The MSG will be DC power based, to avoid the losses that occur when transforming alternating current (AC) into DC.

The ultimate goal of the project is to combine the micro smart grids into a large smart grid for EV charging. Over the next two years, the MSG innovation network will provide interested parties with an opportunity to work up new kinds of smart grid configurations and operating strategies.

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Heavy Hydrogen May Be Key in Making of Organic Solar Cells

Scientists at the Department of Energy’s Oak Ridge National Laboratory have discovered an effect of deuterium, also known as heavy hydrogen, on the analysis of polymer-based solar devices, which may affect how organic solar cells can be constructed. In an article reported by R&D Magazine, the scientists said that the deuterium is used to perform a neutron scattering analysis. Normally, the deuterium is a labeling tool, and has no effect on the substance being studied. But when used on the polymers, deuterium changed the devices’ electronic performance significantly. This means deuterium could potentially be used in the design and structuring of the polymers as solar cells.

More research needs to be done, of course, but the implications could be widespread in a variety of organically-based solar devices such as polymer paint that could be sprayed onto windows to make them into solar cells.

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Students in India Develop Photovoltaic Driven Refrigerator

A team of students in the Innovation And Entrepreneurship Development Centre (IEDC) of RMK Engineering College in India has developed a prototype photovoltaic driven refrigerator and warmer system that could potentially replace appliances that use refrigerants and other liquids for operation. According to an article in the Deccan Chronicle, students Surith Nivas M, Sai Prasad S and Ram Kumar P.H. designed a system powered from solar panels using a battery bank for electrical storage. In an adaptation of thermoelectric refrigeration, the system does not require a compressor, expansion valves, absorbers, condensers or solution pumps. It also does not require working fluids or any moving parts, making it friendly to the environment and resulting in increased reliability. The device uses electrons rather than refrigerants as a heat carrier.

Thermoelectric systems are defined as solid-state devices that either convert heat directly into electricity, or transform electric power into thermal power for heating or cooling.

The system’s primary application will be to bring refrigeration to rural communities, especially in India, where sunlight is plentiful and refrigeration products rare. However, the potential for replacing Freon and similar liquid-based devices could revolutionize the industry.

The team’s findings are reported in a paper posted on the International Journal of Advancements in Research & Technology web site.

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Auto Manufacturers Moving to High-End Electric/Hybrid Vehicles

For the last decade, electric and hybrid automobiles have been designed as smaller models, typically the size and design of subcompact cars. But recent developments in the auto industry have led to the release or planned release of a variety of luxury models and SUVs, offering evidence that electric cars will eventually replace gasoline-powered models. Among the models soon to be released are the Cadillac ELR, a luxury coupe that will come ready for the Smart Grid, meaning that owners will be able to schedule their charging during utility companies’ off-peak hours. It is expected to have a fuel economy rating of 82 mpg.

Volvo plans to deploy its XC90 Twin Engine plug-in hybrid in 2014, a gasoline-electric luxury SUV with at least 300 horsepower, yet carbon dioxide emissions as low 50g/km. The company believes fuel economy could potentially surpass 100 mpg in the U.S.

Infiniti’s Q50 hybrid was recently awarded five stars in the latest round of Euro NCAP safety testing. The luxury sedan uses a 3.5-litre V6 paired with an electric motor to produce a total of 354hp, yet return an anticipated 36 mpg highway.

All these models and several others are expected to compete with BMW’s very successful i8 plug-in hybrid, which has sold out in its first year of availability. Ten thousand i8s were planned for 2014, going on sale by next June, and despite the price tag starting at $136,625, car buyers snapped them up. It uses a three-cylinder, turbocharged gasoline engine rated at 231 horsepower, mated to a 131-hp electric motor. To keep weight down, the i8 uses carbon-fiber construction. The car will go from standstill to 60 mph in 4.4 seconds, BMW says.

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New Solar Cell Design May Dramatically Improve PV Function

Physicists at North Carolina State University say they have found a way to increase the energy handling capacity of solar cells, a discovery that could dramatically improve photovoltaic cell function and productivity in solar panels. As reported on the NC State web site, the new technique improves the connections between stacked solar cells, which should improve the overall efficiency of solar energy devices and reduce the cost of solar energy production. The new connections can allow these cells to operate at solar concentrations of 70,000 suns worth of energy without losing much voltage as “wasted energy” or heat.

By inserting a very thin film of gallium arsenide into the connecting junction of stacked cells the physicists say they can virtually eliminate voltage loss without blocking solar energy, according to Dr. Salah Bedair, a professor of electrical engineering at NC State.

Photovoltaic energy companies are interested in using lenses to concentrate solar energy, from one sun (no lens used) to 4,000 suns or more. But if the solar energy is intensified to 700 suns or more the connecting junctions used in existing stacked cells begin losing voltage. And the more intense the solar energy, the more voltage those junctions lose, thereby reducing the conversion efficiency.

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DC Power Networks Poised for Spectacular Growth

Ready for some spectacular growth? According to a new report from Navigant Research, the total worldwide capacity of direct current (DC) distribution networks will surpass 2.3 gigawatts (GW) by 2025, up from just 196 megawatts (MW) in 2013. In that same period, revenue generated by DC networks is expected to grow nearly tenfold, from $2.8 billion annually in 2013 to $24.1 billion by 2025. The market for DC networks is being fueled by a variety of factors. Two of the more basic drivers are the fact that as much of 80 percent of energy end uses require DC power, and that DC networks eliminate power loss through AC-to-DC conversion.

Of course there are other factors, such as DC’s 8 percent greater efficiency in midrange voltages, and its safe-to-touch 24VDC applications for lighting and other home and office uses. That last factor allows for far greater layout flexibility, as well as ease of installation and repair.

If you think the future will be bright, that’s probably because it will be powered by DC systems.

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