The Environmental Journal of Southern Appalachia

Displaying items by tag: solar panel

Close-up photograph showing the top and bottom of two solar cellsThe rainbow colors show the diffraction of sunlight by a mirror with a nanostructured grating, which was applied to the back of the silicon subcell. The sun’s spectrum is thus captured even better in the silicon bottom cell.  © Fraunhofer ISE / Photo: Michael Schachtner
Fraunhofer Institute for Solar Energy Systems: Tandem Photovoltaics Enables New Heights in Solar Cell Efficiencies – 35.9 % for III-V//Silicon Solar Cell

The photovoltaic (PV) solar panels most commonly used for commercial applications today have an efficiency in the range of 16 to 22 percent. On the lower side of this range, one finds less-expensive panels, mostly made with poly-crystalline solar cells, while monocrystalline cells dominate the upper side.

The highest-efficiency panel presently on the market is SunPower’s A-Series residential panel, with a claimed 22.8 percent efficiency in converting photons to electrons under standard conditions. That's up just slightly by 0.73 percent from five years ago. Although many other manufacturers have caught up to offer panels rated at more than 21 percent, development progress of silicon-based monocrystalline PV toward the theoretical limit of around 30 percent has slowed to a crawl.

Over the same period, newer technologies for multijunction PV cells with thin subcell layers of gallium-arsenide and similar semiconductors, grown on top of silicon or perovskite crystalline materials, has been progressing rapidly and may be capable of exceeding 50 percent efficiency in the future. Lab results still require years of research and manufacturing development before panels come to market. Initially their high price will limit them to market niches where low-weight and small-surface per Watt will justify the cost, such as for aerospace applications or covering electric vehicle surfaces. The following links provide a good overview of such technologies and discuss their longer-term outlook.

DOE Energy Efficiency & Renewable Energy: Multijunction III-V Photovoltaics Research
Frauenhofer ISE: Tandem Photovoltaics – The Road to Higher Conversion Efficiencies
Published in Feedbag

NightUsers can charge devices and access the Internet through two solar-powered charging tables just installed at the Blount County Public Library as part of a larger SkyFi Project to bring access to technology to the community’s disenfranchised.   Courtesy EnerFusion

The Blount County Library, one of Maryville’s busiest spots, was closed to the public from mid-April to the beginning of July 2020, thanks to the pandemic. Even though the library was closed, people pulled their vehicles into the parking lot to access the library’s high-speed Wi-Fi, according to library director K.C. Williams. Some people even got out of their cars and dragged lawn chairs to the sidewalk in front of the building to access the rare public Wi-Fi. 

“We had over 11,000 hits on our Wi-Fi,” while the library was closed, Williams said. It wasn’t the first time that she and her staff realized the vital role they were playing in helping their neighbors access digital resources.

“Our county has 20 percent of the population that’s disenfranchised economically or geographically,” Williams said. “The library is the playing field equalizer.”

Searching for ways to provide more access to the community, she looked at the solar-powered charging picnic tables Maryville College installed on campus a few years ago. The tables, made of recycled plastic, use solar panels to generate and store solar electricity. Manufactured by EnerFusion, the tables cost $12,500 each. The Blount County Friends of the Library secured a grant from the Arconic Foundation for $25,000 to purchase two of them.

The two were installed at the rear of the library and dedicated at a ribbon-cutting Feb. 25. Users will be able to charge devices and access the library’s Wi-Fi any time of the day. The ribbon-cutting also kicked off the larger SkyFi Project, a plan to bring charging tables to accessible locations throughout the community. The Maryville Rotary Club is within $3,000 of meeting its goal to purchase two more tables, which it will install at the Alcoa Duck Pond. Williams said those involved in the project are looking for more locations in Blount County where the tables can be set up with secure Wi-Fi.

“What’s making this work is that it’s a partnership,” Williams said. The project partners are the three library funding bodies (Blount County and the cities of Maryville and Alcoa); the Arconic Foundation (the philanthropical wing of a large community employer); Rotary Club of Maryville; and Blount County Friends of the Library.

Maryville City Councilwoman Sarah Herron was at the ribbon-cutting to celebrate the SkyFi Project.

“Libraries are an important part of something I care deeply about, which is digital equity,” Herron said. She is a digital media specialist and communications professional, and made digital equity and digital literacy part of her candidate platform when she ran for council in 2020. She said that with so many people working remotely, attending virtual classrooms, and using telehealth services, we increasingly require technology, bandwidth, and access to people who can help us navigate tasks online.

“Not everyone has those kinds of resources,” Herron said. She commended director Williams and her staff for “working so hard to close that digital divide,” especially during the pandemic.

Herron predicts that many of the recent changes in how we use technology will persist.  

“Even as we try to get back to ‘normal,’ we’ll continue to rely on more technology,” she said. “There is such a need for people to come together to function in a digital world.”

Published in News