Sep 7 2010

largest Photovoltaic power plants in Bulgaria and Slovakia

The juwi group is a leading project developer for renewable energy installations and built the largest solar park in Bulgaria is located close to Drachevo, a town situated approx. 30 kilometers southwest of the seaport Burgas. With 15,444 crystalline Yingli modules with an output of 3.6 MW 4.3 million kilowatt-hours can be produced – due to excellent irradiation conditions. The solar park is delivering clean energy to 1,300 households since the end of August.

“The prospects for Bulgaria are promising. In the last year wind energy was developed, now Bulgarians discover solar power”, says Lars Falck of juwi Solar a German company that installed the power plant. “We have to see whether the feed-in tariff for solar energy is maintained and whether a tariff fixation without variation for existing plants is implemented. This would contribute to inspiring investors for Bulgaria and to accomplishing the goal for the development of the renewable energies.”

juwi is currently building Slovakia’s largest solar park. It is located close to Kosihy and will produce approx. 4.2 million kilowatt-hours annually with 18,144 crystalline modules by Canadian Solar, with an output of 4 MW. The solar park has a surface of 10 hectares suppllying energy to 1,400 Slovakian households and saves 3,700 tons CO2, it is supposed to be connected to the grid at the beginning of November.

In the Czech Republic the largest solar park is supposed to be completed by at the end of October in Hostovice, which is located 130 kilometres east of the capital Prague; with an output of 5.2 MW it will produce approx 5.5 million kilowatt-hours clean energy for 1,600 households and save almost 4,900 tons CO2 per year. 69,400 thin-film modules by First Solar are currently installed on an area of 15 hectares. juwi Solar is expanding its business in the Czech Republic by the end of 2010 the project developer hopes connect 24 MW to the grid.

“Central and South-Eastern Europe offer great perspectives. Whether we can use these potentials to promote a lasting, eco-friendly energy supply with solar energy is dependant on future basic conditions”, says managing director Lars Falck. “If these conditions remain attractive, there is nothing opposing investments in Central and Eastern Europe”.

By jimmy • News • 0 • Tags: Photovoltaic News

Sep 6 2010

New self-assembling photovoltaic technology

At the Massachusetts Institute of Technology in the USA Professor Michael Strano and his team have succeeded in mimicking a key aspect of plants to store energy.

New self-assembling photovoltaic technology that repairs itself
Molecules can turn sunlight into electricity and can be broken down and quickly reassembled.

Plants are good at doing what scientists and engineers have been struggling to do for decades: converting sunlight into stored energy, and doing so reliably day after day, year after year. Now some MIT scientists have succeeded in mimicking a key aspect of that process.

One of the problems with harvesting sunlight is that the sun’s rays can be highly destructive to many materials. Sunlight leads to a gradual degradation of many systems developed to harness it. But plants have adopted an interesting strategy to address this issue: They constantly break down their light-capturing molecules and reassemble them from scratch, so the basic structures that capture the sun’s energy are, in effect, always brand new.

That process has now been imitated by Michael Strano, the Charles and Hilda Roddey Associate Professor of Chemical Engineering, and his team of graduate students and researchers. They have created a novel set of self-assembling molecules that can turn sunlight into electricity; the molecules can be repeatedly broken down and then reassembled quickly, just by adding or removing an additional solution. Their paper on the work was published on Sept. 5 in Nature Chemistry.

Strano says the idea first occurred to him when he was reading about plant biology. “I was really impressed by how plant cells have this extremely efficient repair mechanism,” he says. In full summer sunlight, “a leaf on a tree is recycling its proteins about every 45 minutes, even though you might think of it as a static photocell.”

From left to right, Associate Professor Michael Strano with graduate student Ardemis Boghossian and postdoctoral fellow Moon-Ho Ham, in one of the labs where they carried out their experiments. Photo: Patrick Gillooly

One of Strano’s long-term research goals has been to find ways to imitate principles found in nature using nanocomponents. In the case of the molecules used for photosynthesis in plants, the reactive form of oxygen produced by sunlight causes the proteins to fail in a very precise way. As Strano describes it, the oxygen “unsnaps a tether that keeps the protein together,” but the same proteins are quickly reassembled to restart the process.

This action all takes place inside tiny capsules called chloroplasts that reside inside every plant cell — and which is where photosynthesis happens. The chloroplast is “an amazing machine,” Strano says. “They are remarkable engines that consume carbon dioxide and use light to produce glucose,” a chemical that provides energy for metabolism.

To imitate that process, Strano and his team, supported by grants from the MIT Energy Initiative and the Department of Energy, produced synthetic molecules called phospholipids that form discs; these discs provide structural support for other molecules that actually respond to light, in structures called reaction centers, which release electrons when struck by particles of light. The discs, carrying the reaction centers, are in a solution where they attach themselves spontaneously to carbon nanotubes — wire-like hollow tubes of carbon atoms that are a few billionths of a meter thick yet stronger than steel and capable of conducting electricity a thousand times better than copper. The nanotubes hold the phospholipid discs in a uniform alignment so that the reaction centers can all be exposed to sunlight at once, and they also act as wires to collect and channel the flow of electrons knocked loose by the reactive molecules.

The system Strano’s team produced is made up of seven different compounds, including the carbon nanotubes, the phospholipids, and the proteins that make up the reaction centers, which under the right conditions spontaneously assemble themselves into a light-harvesting structure that produces an electric current. Strano says he believes this sets a record for the complexity of a self-assembling system. When a surfactant — similar in principle to the chemicals that BP has sprayed into the Gulf of Mexico to break apart oil — is added to the mix, the seven components all come apart and form a soupy solution. Then, when the researchers removed the surfactant by pushing the solution through a membrane, the compounds spontaneously assembled once again into a perfectly formed, rejuvenated photocell.

“We’re basically imitating tricks that nature has discovered over millions of years” — in particular, “reversibility, the ability to break apart and reassemble,” Strano says. The team, which included postdoctoral researcher Moon-Ho Ham and graduate student Ardemis Boghossian, came up with the system based on a theoretical analysis, but then decided to build a prototype cell to test it out. They ran the cell through repeated cycles of assembly and disassembly over a 14-hour period, with no loss of efficiency.

Strano says that in devising novel systems for generating electricity from light, researchers don’t often study how the systems change over time. For conventional silicon-based photovoltaic cells, there is little degradation, but with many new systems being developed — either for lower cost, higher efficiency, flexibility or other improved characteristics — the degradation can be very significant. “Often people see, over 60 hours, the efficiency falling to 10 percent of what you initially saw,” he says.

The individual reactions of these new molecular structures in converting sunlight are about 40 percent efficient, or about double the efficiency of today’s best commercial solar cells. Theoretically, the efficiency of the structures could be close to 100 percent, he says. But in the initial work, the concentration of the structures in the solution was low, so the overall efficiency of the device — the amount of electricity produced for a given surface area — was very low. They are working now to find ways to greatly increase the concentration.

By jimmy • News • 1 • Tags: Photovoltaic News

Sep 4 2010

German Solar Demand on Record Pace in 2010

Photovoltaic system installations in the first half of 2010, estimated at 3 GWp, continue to consolidate Germany’s position as the world’s largest photovoltaic (PV) market.

In 2009, Germany accounted for approximately one of every two newly installed modules worldwide, with total installations at 3.8 GWp for the year.

Amendments to the photovoltaic feed-in tariffs of Germany’s Renewable Energies Act (EEG) were passed in early July, with a further adjustment to take effect in October . The changes mark a further shift towards the rooftop segment by abandoning field installations on cropland and increasing the attractiveness of the own consumption bonus for small and medium-scale rooftop installations. This bonus is paid to rooftop installation owners of systems smaller than 500 kWp who intend to use the energy they generate.

Feed-in tariff rates were reduced by 13 percent for rooftop installations and eliminated for cropland field installations from July 1. At the same time, conversion areas saw a reduction of 8 percent and all other areas were decreased by 12 percent. Beginning October 1st, these rates will be reduced by a further 3 percent. The law, established ten years ago, requires power companies to buy renewable energy from system owners at the corresponding feed-in tariff rate for 20 years, guaranteeing an attractive payback time and high returns.

By jimmy • News • 0 • Tags: Photovoltaic News