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Category Archives: solar energy
A Look Inside Four Solar Labs Offers a Glimpse of What’s New in PV R&D
NREL post-doc scientist, Rene Rivero, operates a Solar/Wafer Screening Tool for PV Industry. This tool tests a pre-selection of wafers of high fracture strength, improving the yield of Si solar cells by preventing their breakage during cell fabrication. Courtesy NREL.
NREL
Greg Wilson, director of the National Center for Photovoltaics at the National Renewable Energy Laboratory in Golden, CO, reports that his facility has is conducting research in three major areas. For starters, researchers are working in the III-Vs, which refers to semiconductors made from atoms in columns III and V of the periodic table, the most common one being gallium arsenide.
Another part of its research is in conventional single-crystal silicon. “Nearly all of our work at NREL right now is focused on silicon tandems. This involves taking the best cell made and adding a top cell that will harvest another portion of the light spectrum in a two-junction cell,” Wilson says. Many groups around the world are working on this concept, which poses a challenge in getting the cell joined cost effectively, whether you use epitaxy or bonding. NREL is exploring both routes and says the top cell will likely be a III-V.
If done correctly, Wilson says, this has the potential to add about ten points of efficiency to an already high-efficiency silicon part itself. “This approach could produce silicon tandems and have an efficiency of greater than 30 percent.”
The third area is thin-film, which NREL has been exploring for 35 years. Researchers are investigating different materials, including cadmium telluride (the semiconductor that First Solar technology is based on), CIGS (copper indium gallium selenium), and a GIGS substitute known as CZTS, an earth-abundant potential replacement.
Thin-film offers advantages over conventional cells made with crystalline semiconductor material, mainly lower manufacturing costs because it uses a low-temperature process similar to printing instead of the high-temperature vacuum deposition process. It also has the advantage of lighter weight and the ability to be integrated into building materials such as siding, roofing, and tent fabrics.
But as Wilson says, “Silicon isn’t going anywhere. There are a lot of reasons silicon dominates the market today.” Thin-film hasn’t achieved the efficiency silicon has. “There’s another problem with thin-films that’s always out there, and that’s long-term reliability. Silicon has the best, most well-understood degradation behavior over 30 years in the field.” Polycrystalline thin-films degrade faster than silicon, but Wilson thinks that can be solved with more research.
Revolutionary solar-friendly form of silicon shines
Their work is published in Nature Materials.
Although silicon is incredibly common in today’s technology, its so-called indirect band gap semiconducting properties prevent it from being considered for next-generation, high-efficiency applications such as light-emitting diodes, higher-performance transistors and certain photovoltaic devices.
Metallic substances conduct electrical current easily, whereas insulating (non-metallic) materials conduct no current at all. Semiconducting materials exhibit mid-range electrical conductivity. When semiconducting materials are subjected to an input of a specific energy, bound electrons can move to higher-energy, conducting states. The specific energy required to make this jump to the conducting state is defined as the «band gap.» While direct band gap materials can effectively absorb and emit light, indirect band gap materials, like diamond-structured silicon, cannot.
In order for silicon to be more attractive for use in new technology, its indirect band gap needed to be altered. Strobel and his team—Carnegie’s Duck Young Kim, Stevce Stefanoski and Oleksandr Kurakevych (now at Sorbonne) —were able to synthesize a new form of silicon with a quasi-direct band gap that falls within the desired range for solar absorption, something that has never before been achieved.
The silicon they created is a so-called allotrope, which means a different physical form of the same element, in the same way that diamonds and graphite are both forms of carbon. Unlike the conventional diamond structure, this new silicon allotrope consists of an interesting open framework, called a zeolite-type structure, which is composed of channels with five-, six- and eight-membered silicon rings.
They created it using a novel high-pressure precursor process. First, a compound of silicon and sodium, Na4Si24, was formed under high-pressure conditions. Next, this compound was recovered to ambient pressure, and the sodium was completely removed by heating under vacuum. The resulting pure silicon allotrope, Si24, has the ideal band gap for solar energy conversion technology, and can absorb, and potentially emit, light far more effectively than conventional diamond-structured silicon. Si24 is stable at ambient pressure to at least 842 degrees Fahrenheit (450 degrees Celsius).
«High-pressure precursor synthesis represents an entirely new frontier in novel energy materials,» remarked Strobel. «Using the unique tool of high pressure, we can access novel structures with real potential to solve standing materials challenges. Here we demonstrate previously unknown properties for silicon, but our methodology is readily extendible to entirely different classes of materials. These new structures remain stable at atmospheric pressure, so larger-volume scaling strategies may be entirely possible.»
«This is an excellent example of experimental and theoretical collaboration,» said Kim. «Advanced electronic structure theory and experiment have converged to deliver a real material with exciting prospects. We believe that high-pressure research can be used to address current energy challenges, and we are now extending this work to different materials with equally exciting properties.»
Juwi is building a 50-MW solar park in Utah
Nearly 300,000 solar panels, a total size of 87 hectares and clean energy for 10,000 households – these are the impressive dimensions of the solar and agricultural park Ortaffa. The photovoltaic power plant in the French Pyrenees close to the Spanish border is the biggest solar project the internationally operating juwi group has ever built in France so far. What is more, through special measures the park revives the local tradition of sheep farming and beekeeping on-site and enables the agricultural heritage of wine-growing to rise again.
Brazil to overtake US as world’s leader for biopower
According to research and consulting company GlobalData, in 2018 Brazil will overtake the US as the world’s leader in terms of biopower capacity. In 2013, Brazil had 11.5 GW and the US had 15.4 GW of installed bioenergy capacity. In 2018 these will have risen to 17.1 GW for Brazil and 16.5 GW for the US market, according to GlobalData.
This is due to Brazil’s increasing pace of capacity addition, fuelled by its government, explains GlobalData analyst Harshavardhan Reddy Nagatham: “The nascent Brazilian market is being driven by the government, which has made it necessary for local utility service providers to obtain at least 2 GW of installed biomass capacity through auctions annually, for ten years from 2007.” In 2006, Brazil still had less than 4 GW of installations while a big part of the US’s biopower capacity had already been installed (12.8 GW) with only small additions following afterwards.
As Nagatham points out, it is possible that due to increased deforestation, raw materials could be scarce, but that a rise in sugarcane plantations will most likely compensate for this. “The abundance of sugarcane in Brazil makes the installation of biomass technology a very viable option for power generation”, he elaborates, “biomass projects will also generate electricity from both sugarcane waste and non-food energy crops, such as eucalyptus and pine trees.”
Nagatham concludes the biggest challenge for biopower to be other renewable energies such as hydropower and wind energy and natural gas, since the Brazilian Development Bank would show a preference towards those, when it comes to financing renewable projects.
Nevertheless, GlobalData’s study expects biopower in Brazil to surge up to 25.2 GW in 2025.
You can order the full study here: Global Biopower Market — Capacity, Generation, Market Size, Major Feedstock, Regulations, and Key Country Analysis to 2025
Tanja Peschel
Low-Cost Solar Panel Captures Four Times More Energy
LAS CRUCES, NM.—(eSolarEnergyNews)—Focused Sun of Las Cruces, New Mexico, USA (www.focused-sun.com) is planning to shake up the solar industry with an inexpensive module that captures four times more energy than a conventional solar panel of the same size. The module, called FourFold, produces both electricity and hot water. It can pay for itself in as little as two years, bringing local jobs plus cheap, clean energy. For every dollar spent, you capture four fold more solar energy.
A FourFold covers most of modern energy needs: its electricity powers lights, refrigerators and air cooling, while its heat can warm a home or drive boilers. In the developing world, the module is needed in village clinics where it can sterilize water and refrigerate vaccines.
The fabrication technology to make FourFold solar modules in small local factories can be licensed from Focused Sun. A town as small as 5,000 can support a solar factory. These aren’t short term jobs: most towns and small cities will take decades to solarize.
Costs of the module’s collector are similar to a same-sized conventional PV panel because sandwich fabrication is used for the module’s mirrors. Sandwich fabrication is the most efficient structure for resisting the wind, the highest force a solar panel must withstand.
Conventional PV solar panels capture 20% of the sun’s energy as electricity. In the FourFold module, four mirrors concentrate the sunlight into a narrow strip of overhead PV cells, capturing just as much electricity. More important, coolant pumped through the absorber captures an additional 55% of the sun’s energy as heat. Altogether, the FourFold collects 75% of the sun’s energy, 500 W of electricity and 1500 W of heat for 2000 W total.
The attached shed stores energy overnight: heat in an insulated tank and electricity in batteries. With low costs and high efficiency solar capture, payback can be as low as 2 years.
Focused Sun founder Rene Francis (Hallsberg, Sweden) said, “This solar technology can outperform anything else you could find in the world. And the best part is it can be built locally.” Referring to Princeton University’s eight stabilization wedges needed to avoid global warming, he adds, “If PV solar is one Princeton wedge, then this technology is four wedges. That’s half the global warming problem.”
Canadian Solar Supplies Modules for Major Solar Project in Georgia
GUELPH, ONTARIO—(eSolarEnergyNews)— Canadian Solar today announced that its modules will power a series of projects in Georgia totaling 5.1 MW with Atlanta-based solar developer and Engineering, Procurement and Construction («EPC») provider SolAmerica Energy, LLC. As the sole provider of photovoltaic (PV) modules for these projects, Canadian Solar expects these projects to be completed in December of 2014.
Each of the projects will be owned by Citizens Energy Corporation of Boston pursuant to a development and EPC Agreement with SolAmerica Energy. All of the projects will utilize Canadian Solar CS6X-310-P photovoltaic (PV) modules, and the energy produced from the arrays will be sold to Georgia Power pursuant to the Georgia Power Advanced Solar Initiative.
The projects under construction include the following:
- Taylor County Industrial Park in Butler, Georgia: 1.8 MW ground mount
- Cook County Farm in Lenox, Georgia: 1.3 MW ground mount
- Terrell County Industrial Park in Dawson, Georgia: 1 MW ground mount
- Goolsby Farm in Terrell County, Georgia: 1 MW ground mount
R. Stanley Allen, President of SolAmerica, said, «As part of the 8 MW of solar projects that SolAmerica will develop and build in Georgia by the end of 2014, these projects will help grow the base of solar energy in Georgia. Based on the performance and reliability of Canadian Solar PV modules in previous projects we developed, we hold full confidence in their product performance.»
Dr. Shawn Qu, Chairman and Chief Executive Officer of Canadian Solar, commented, «Canadian Solar is pleased to be working with SolAmerica on these solar projects in Georgia. We await their completion very soon and also look forward to future projects with SolAmerica in the Southeast United States.»
South Africa’s New 96MW PV Plant is the Continent’s Largest Solar Power Facility
South Africa is a historically coal-hungry nation, producing around 225 million tonnes of the stuff each year. But just two years ago, government leaders pledged to invest an incredible $5.4 billion in renewable energy, and the products of that investment are taking shape. The Jasper PV Project in Kimberly, South Africa, became fully operational in October, and produces enough power to serve an impressive 80,000 homes. It’s now the largest solar power plant in Africa. The better news? It’s soon to be eclipsed by an even bigger facility nearby.
The Jasper PV Project has a rated capacity of 96 megawatts, and will produce 180,000 megawatt-hours of clean energy each year—enough to power 80,000 homes with power purchased by Eksom, a local public utility. The project was developed by a consortium led by Solar Reserve, who in addition to Jasper also constructed the adjacent 75 MW Lesedi Power Project, and are at work on the 100 MW Redstone Concentrated Solar Power Tower project.
Related: South Africa Approves $5.4 Billion in Renewable Energy Projects to Provide 1,400MW by 2016
Not only are these projects a huge step towards South Africa’s efforts to have 1,400 MW of renewable energy by 2016, but they also serve as a significant economic boon. According to Treehugger, the Jasper PV Project provided one million hours of paid work during construction, and peaked with over 800 on-site construction jobs. Funding for Jasper came from both local and international sources—including Google, who have, to date, committed $1.5 billion to the development of clean energy wind and solar projects internationally.
In South Africa, these large scale renewable energy projects are particularly pertinent, not just in reducing the nation’s coal dependence, but also in bolstering the grid to prevent power shortages, which have caused rolling blackouts in the country.
+ Solar Reserve
Via Treehugger
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SunPower Adds AC Inverters To Lineup To Save One-Third Labor Cost
The move has been acclaimed for its expected help in building SunPower’s residential business, since statistics for first quarter 2014 indicate more MWs of PV were installed in residential systems than in commercial systems since 2010. The acquisition was also praised for being an investment aimed at bringing more downstream electronics into the panel, and for being a panel development improvement outside of traditional research directions.
But of perhaps of greater significance to the residential solar industry as a whole is the soft cost savings advantage of the SolarBridge TRUEAC system, which the manufacturer announced in a study, on October 15, with a cost savings of 33 percent over string inverters, according to Bryan Thomas, SolarBridge’s director of product management, and the author of the study.
The SolarBridge study goal was to build on recent balance of system soft cost analysis by Rocky Mountain Institute and Georgia Tech Research Institute, which compared soft costs in the United States to those in Germany. That analysis revealed that German costs are 73 percent lower than those in the United States.
But since the RMI and similar U.S. National Renewable Energy Laboratory (NREL) focused only on string inverters for the basis of their comparison, SolarBridge did its own survey, also comparing the cost when SolarBridge TRUEAC modules were used, when detached microinverters were used, and when a combination of string inverters and DC optimizers were used.
SolarBridge surveyed “32 installers in 16 key solar states across the country” and found that “for an average 5 kW residential system, TRUEAC module use reduced total labor costs by 33 percent compared to a string inverter, as well as by 35 percent compared to an Enphase detached microinverter, and by 48 percent compared to a SolarEdge power optimizers,” according to Bryan Thomas, SolarBridge’s director of product management.
Employing a team of four — including two non-electricians and two electricians — the average installation time for a string inverter based residential system is 2.4 days, the study indicates. Survey respondents with relevant experience said using SolarBridge TRUEAC modules reduced their installation time by an average of 24 percent compared to using string inverters in the same installation, it concludes.
SunPower had already utilized SolarBridge’s AC inverters for several years prior to the acquisition, and now the AC inverters are expected to be tailored to the former’s top-of-the-line X-Series residential panels.
Europe Still #1 in Relative Solar Energy Production
A new report from the IEA has several interesting charts on solar PV power. Each of the charts is worth a gander, but there’s one that stands out in particular to me, because it shows a much different picture than many of the others.
Basically, many of the charts show that China, Japan, and the US dominated new solar PV power installations in 2013, and that they also compare well (come in #2, #4, and #5) in cumulative solar PV power capacity through the end of 2013. However, if you look at solar PV electricity production relative to electricity demand in each country, you can see that European countries dominate. China and the US even come in below the global average. Japan comes in #13.
In other words, China, the US, and Japan may dominate the headlines for their large solar capacity additions, but they really have a long ways to go to catch up with Italy, Germany, Greece, the Czech Republic, Bulgaria, Spain, Belgium, Romania, Slovakia, and Denmark.
The good news is that they are growing fast, and they have these European leaders to look up to. Europe’s success should inspire these global economic giants to hasten their solar power growth, and it should also given them the assurance that much higher penetration of solar power generation works and can be achieved right now.
Of course, every country on earth needs to increase its use of solar power a great deal. Even solar power in world-leading Italy is just at about 7.5 percent of its total electricity demand. Kudos to the European leaders, but don’t lose momentum now.
Originally published on Sustainnovate.