May
27
2016

BMW Rolls Out New Solar Carports in South Africa

The solar carport rollout is part of the German automaker’s global efforts to expand home and publicly accessible charging infrastructure for electric vehicles.

BMW’s solar carport is made of high-end bamboo and stainless steel housing for the glass solar modules. BMW

German automaker BMW has unveiled its new solar carports in South Africa, which it will begin rolling out in July.

The BMW i solar carport supplies an average of 3.6 kW of solar power straight to the BMW i Wallbox, which is used to charge electric and plug-in hybrid BMW models and which is equipped with a live readout of how much power is being generated by the sun.

Tim Abbott, CEO of BMW Group South Africa and Sub-Sahara, said the company was the first automaker to offer such a broad-based EV smart charging product to reduce costs for customers. The rollout is part of the company’s global efforts to expand home and publicly accessible charging infrastructure for electric vehicles, Abbott added.

In the coming months, BMW Group South Africa will expand the installation of the solar carport in major cities, including Johannesburg, Cape Town and Durban, for public charging.

Customers and fleet companies will also be able to order the solar carport for home and office charging.

“We have always emphasised that in order for electric vehicles and plug-in hybrid electric vehicles to be successful, we need to firstly increase consumer confidence in the viability of electric vehicles and secondly make public charging easily accessible for customers who purchase these cars,” Abbott said. “The rollout of the solar carport is also an emphasis on this philosophy.”

The solar carport is produced by PV solar system designer and installer Sunworks. It is made of high-end bamboo and stainless steel housing for the glass solar modules.

Bamboo is considered a particularly sustainable and high strength-to-weight ratio natural composite material useful for structures, BMW said.

Courtesy: http://www.pv-magazine.com/news/

May
25
2016

Hot New Solar Cell

While all research in traditional photovoltaics faces the same underlying theoretical limitations, MIT PhD student David Bierman says, “with solar thermal photovoltaics you have the possibility to exceed that.” In fact, theory predicts that in principle this method could more than double the theoretical limit of efficiency, potentially making it possible to deliver twice as much power from a given area of panels. Photo courtesy of the researchers.

System converts solar heat into usable light, increasing device’s overall efficiency.

By: David L. Chandler

A team of MIT researchers has for the first time demonstrated a device based on a method that enables solar cells to break through a theoretically predicted ceiling on how much sunlight they can convert into electricity.

Ever since 1961 it has been known that there is an absolute theoretical limit, called the Shockley-Queisser Limit, to how efficient traditional solar cells can be in their energy conversion. For a single-layer cell made of silicon — the type used for the vast majority of today’s solar panels — that upper limit is about 32 percent. But it has also been known that there are some possible avenues to increase that overall efficiency, such as by using multiple layers of cells, a method that is being widely studied, or by converting the sunlight first to heat before generating electrical power. It is the latter method, using devices known as solar thermophotovoltaics, or STPVs, that the team has now demonstrated.

The findings are reported this week in the journal Nature Energy, in a paper by MIT doctoral student David Bierman, professors Evelyn Wang and Marin Solja?i?, and four others.

While all research in traditional photovoltaics faces the same underlying theoretical limitations, Bierman says, “with solar thermophotovoltaics you have the possibility to exceed that.” In fact, theory predicts that in principle this method, which involves pairing conventional solar cells with added layers of high-tech materials, could more than double the theoretical limit of efficiency, potentially making it possible to deliver twice as much power from a given area of panels.

“We believe that this new work is an exciting advancement in the field,” Wang says, “as we have demonstrated, for the first time, an STPV device that has a higher solar-to-electrical conversion efficiency compared to that of the underlying PV cell.” In the demonstration, the team used a relatively low-efficiency PV cell, so the overall efficiency of the system was only 6.8 percent, but it clearly showed, in direct comparisons, the improvement enabled by the STPV system.

The basic principle is simple: Instead of dissipating unusable solar energy as heat in the solar cell, all of the energy and heat is first absorbed by an intermediate component, to temperatures that would allow that component to emit thermal radiation. By tuning the materials and configuration of these added layers, it’s possible to emit that radiation in the form of just the right wavelengths of light for the solar cell to capture. This improves the efficiency and reduces the heat generated in the solar cell.

The key is using high-tech materials called nanophotonic crystals, which can be made to emit precisely determined wavelengths of light when heated. In this test, the nanophotonic crystals are integrated into a system with vertically aligned carbon nanotubes, and operate at a high temperature of 1,000 degrees Celsius. Once heated, the nanophotonic crystals continue to emit a narrow band of wavelengths of light that precisely matches the band that an adjacent photovoltaic cell can capture and convert to an electric current. “The carbon nanotubes are virtually a perfect absorber over the entire color spectrum,” Bierman says, allowing it to capture the full solar spectrum. “All of the energy of the photons gets converted to heat.” Then, that heat gets re-emitted as light but, thanks to the nanophotonic structure, is converted to just the colors that match the PV cell’s peak efficiency.

In operation, this approach would use a conventional solar-concentrating system, with lenses or mirrors that focus the sunlight, to maintain the high temperature. An additional component, an advanced optical filter, lets through all the desired wavelengths of light to the PV cell, while reflecting back any unwanted wavelengths, since even this advanced material is not perfect in limiting its emissions. The reflected wavelengths then get re-absorbed, helping to maintain the heat of the photonic crystal.

Bierman says that such a system could offer a number of advantages over conventional photovoltaics, whether based on silicon or other materials. For one thing, the fact that the photonic device is producing emissions based on heat rather than light means it would be unaffected by brief changes in the environment, such as clouds passing in front of the sun. In fact, if coupled with a thermal storage system, it could in principle provide a way to make use of solar power on an around-the-clock basis. “For me, the biggest advantage is the promise of continuous on-demand power,” he says.

In addition, because of the way the system harnesses energy that would otherwise be wasted as heat, it can reduce excessive heat generation that can damage some solar-concentrating systems.

To prove the method worked, the team ran tests using a photovoltaic cell with the STPV components, first under direct sunlight and then with the sun completely blocked so that only the secondary light emissions from the photonic crystal were illuminating the cell. The results showed that the actual performance matched the predicted improvements.

“A lot of the work thus far in this field has been proof-of-concept demonstrations,” Bierman says. “This is the first time we’ve actually put something between the sun and the PV cell to prove the efficiency” of the thermal system. Even with this relatively simple early-stage demonstration, Bierman says, “we showed that just with our own unoptimized geometry, we in fact could break the Shockley-Queisser limit.” In principle, such a system could reach efficiencies greater than that of an ideal solar cell.

The next steps include finding ways to make larger versions of the small, laboratory-scale experimental unit, and developing ways of manufacturing such systems economically.

This represents a “significant experimental advance,” says Peter Bermel, an assistant professor of electrical and computer engineering at Purdue University, who was not associated with this work. “To the best of my knowledge, this is a new record for solar TPV, using a solar simulator, selective absorber, selective filter, and photovoltaic receiver, that reasonably represents actual performance that might be achievable outdoors.” He adds, “It also shows that solar TPV can exceed PV output with a direct comparison of the same cells, for a sufficiently high input power density, lending this approach to applications using concentrated sunlight.”

The research team also included MIT alumnus Andrej Lenert PhD ’14, now a research fellow at the University of Michigan, MIT postdocs Walker Chan and Bikram Bhatia, and research scientist Ivan Celanovic. The work was supported by the Solid-State Solar Thermal Energy Conversion (S3TEC) Center, funded by the U.S. Department of Energy.

Courtesy: http://news.mit.edu/2016/hot-new-solar-cell-0523

 

 

 

May
23
2016

Solar Panel Turns Raindrops Into Power

Thinkstock

An innovative solar panel technology could turn raindrops into electric power, according to scientists in China.

The new solar cell design, which can be “triggered” by both rain and sun, is described in a paper published in the Angewandte Chemie journal.

“All-weather solar cells are promising in solving the energy crisis,” explain the scientists from Ocean University of China and Yunnan Normal University, noting that the technology combines an electron-enriched graphene electrode with a dye-sensitized solar cell. “The new solar cell can be excited by incident light on sunny days and raindrops on rainy days,” they add.

Dye-sensitized solar cells are thin-film photovoltaic cells that harness organic dye to absorb sunlight and produce electrons, thereby creating energy.

The new technology could guide the design of advanced all-weather solar cells, according to the scientists.

The Science News Journal notes that, by using a thin layer of highly conductive graphene, the solar cell could effectively harness power from rain. “The salt contained in rain separates into ions (ammonium, calcium and sodium), making graphene and natural water a great combination for creating energy,” it reports. “The water actually clings to the graphene, forming a dual layer (AKA pseudocapacitor) with the graphene electrons. The energy difference between these layers is so strong that it generates electricity.”

Vasilis Fthenakis, a senior research scientist and adjunct professor at Columbia University who did not participate in the paper, told FoxNews.com that, if the technology’s additional costs and potential solar cell optical losses do not exceed the benefits of rain-harvested energy, it could be used in climates not typically associated with strong solar energy. “The dye-sensitized cells where this is applied are not the type of technology that would be deployed globally as a replacement of conventional energy; they have applications mostly in diffuse-light applications, not in the high sun regions,” he said, via email.

Optical loss refers to potential solar cell energy lost through, for example, reflection or transmission.

China is one of the world’s major solar panel manufacturing bases and expects to significantly increase its own use of the technology over the coming years. In an attempt to reduce its carbon emissions, the country wants to triple its solar power capacity to as much as 143 gigawatts by 2020, according to a recent Bloomberg report.

U.S. firms are also looking to drive solar energy innovation. Last year SolarCity, which was co-founded by Tesla CEO Elon Musk, announced that it will make its most-cutting-edge solar panels in the United States. The San Mateo, Calif.-based firm will build its most-efficient rooftop solar panels at a huge new facility in Buffalo, N.Y. The factory is expected to reach full capacity in 2017.

Courtesy: http://news.discovery.com/tech/

May
21
2016

Portugal Runs for Four Days Straight on Renewable Energy Alone

Zero emission milestone reached as country is powered by just wind, solar and hydro-generated electricity for 107 hours

As recently as 2013, renewables provided only about 23% of Portugal’s electricity. By 2015 that figure had risen to 48%. Photograph: Pete Titmuss/Alamy Stock Photo

Portugal kept its lights on with renewable energy alone for four consecutive days last week in a clean energy milestone revealed by data analysis of national energy network figures.

Electricity consumption in the country was fully covered by solar, wind and hydro power in an extraordinary 107-hour run that lasted from 6.45am on Saturday 7 May until 5.45pm the following Wednesday, the analysis says.

News of the zero emissions landmark comes just days after Germany announced that clean energy had powered almost all its electricity needs on Sunday 15 May, with power prices turning negative at several times in the day – effectively paying consumers to use it.

Oliver Joy, a spokesman for the Wind Europe trade association said: “We are seeing trends like this spread across Europe – last year with Denmark and now in Portugal. The Iberian peninsula is a great resource for renewables and wind energy, not just for the region but for the whole of Europe.”

James Watson, the CEO of SolarPower Europe said: “This is a significant achievement for a European country, but what seems extraordinary today will be commonplace in Europe in just a few years. The energy transition process is gathering momentum and records such as this will continue to be set and broken across Europe.”

Last year, wind provided 22% of electricity and all renewable sources together provided 48%, according to the Portuguese renewable energy association.

While Portugal’s clean energy surge has been spurred by the EU’s renewable targets for 2020, support schemes for new wind capacity were reduced in 2012.

Despite this, Portugal added 550MW of wind capacity between 2013 and 2016, and industry groups now have their sights firmly set on the green energy’s export potential, within Europe and without.

“An increased build-out of interconnectors, a reformed electricity market and political will are all essential,” Joy said. “But with the right policies in place, wind could meet a quarter of Europe’s power needs in the next 15 years.”

In 2015, wind power alone met 42% of electricity demand in Denmark, 20% in Spain, 13% in Germany and 11% in the UK.

In a move hailed as a “historic turning point” by clean energy supporters, UK citizens last week enjoyed their first ever week of coal-free electricity generation.

Watson said: “The age of inflexible and polluting technologies is drawing to an end and power will increasingly be provided from clean, renewable sources.”

This article was amended on 19 May 2016. An earlier version said that in 2013 Portugal generated 27% of its electricity from nuclear, 13% from hydro, 7.5% from wind and 3% from solar, according to Eurostat figures. In fact those figures are for the whole of the EU; Portugal does not have any nuclear power plants.

Courtesy: http://www.theguardian.com/environment/

May
19
2016

Greener Ways to Warm and Cool Your Home

child in bath
For many home owners, the subject of energy efficiency is one that they want to learn more about. Making your home more energy efficient does not only help you to be kinder to the environment and reduce your carbon footprint, it can also result in some serious savings on your energy bills, leaving you with more disposable income at the end of the month. There are a whole range of different ways in which you can make your home become more energy efficient, many of which don’t even involve cutting your energy usage down. By making smart changes to the appliances which you use at home, you can use less energy and therefore spend less money without even realising it.

Your Bathroom

When it comes to the rooms which use the most energy at home, your bathroom is definitely high up on the list. Going green with your bathroom is one of the best ways to save energy and heat up the necessary water that you use without spending too much money or causing too much damage to the environment. Installing eco-friendly water heaters or bathroom towel heaters from MHS Range Radiators, for example, can make your bathroom a greener and more energy efficient environment.

Heating Your Home

Heating your entire home, especially during the colder months, can make up a huge chunk of your energy bill. However, it’s not always plausible to turn your heating off during the winter in order to save money – nobody likes walking around their home wrapped up in an outdoor coat and five pairs of socks! Rather than leaving the heating on in your home when you’re not in to make sure that it’s at a nice, comfortable temperature when you return, investing in a programmable thermostat is a great way to be more energy efficient and green when it comes to heating your home. Programmable thermostats can be set to heat up your home at certain times in the day, making it easy to come home to a warm house without the huge financial cost.

Energy Audit

One of the best ways to discover which areas could be improved when it comes to being more energy efficient when heating and cooling your home is to perform an energy audit. This involves auditing your home in order to find areas where hot and cold air could be escaping, causing your heating and cooling systems to use more energy and therefore impacting on the energy bills that you pay. When carrying out a home energy audit, the first places that you should look are around doors and windows. Weather stripping coming away, badly fitted windows and doors and even the tiniest of gaps can all have an impact on the energy that you use at home. Finding these problem areas and repairing them is the first step towards using less energy and being kinder to the environment when heating and cooling your home.

‘Going green’ doesn’t always have to mean using self-generated energy – it also involves making smart choices when it comes to the energy that you use in order to keep it to a minimum.

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