Posted tagged ‘solar cells’

Dual-Junction Solar Cell Sets World Efficiency Record at 32.6 Percent at 1000 suns

November 18, 2008

Via: Semiconductor Today

The III-V Semiconductors group of the Instituto de Energía Solar at Universidad Politécnica de Madrid (IES-UPM) in Spain has set a new record for solar energy conversion efficiency of 32.6% for a dual-junction photovoltaic cell.

Designed and fabricated in a horizontal MOCVD reactor by IES-UPM’s III-V Semiconductors group, the lattice-matched dual-junction solar cell was independently measured at the calibration laboratory of the Fraunhofer Institute for Solar Energy Systems (FhG-ISE) in Freiburg, Germany. The 32.6% efficiency was measured under light concentration of 1026 suns (where one sun is the amount of light that typically hits the Earth on a sunny day), while at 2873 suns the efficiency is still 31.1%. 

Professor Carlos Algora, director of the group, says that the new cell is an important advance for terrestrial concentrated photovoltaic (CPV) modules, which use lenses or mirrors to focus sunlight onto the solar cells. 

Courtesy of Madri+dIES-UPM says that its new solar cell differs significantly from the previous record holder, made by Fraunhofer ISE (which, in 2000, achieved 31% at 300 suns). It adds that the importance of the new record is not only the efficiency increase of 1.6%, but also the concentration level (1026 suns versus 300 suns). As a rule of thumb, the higher the concentration, the lower the resulting price of the generated electricity. IES-UPM reckons that, after about five years of development, the cost of solar electricity from CPV systems based on this type of solar cell would be about 5.5c€/kWh, while at present the cost of electricity in Spain (generated by all available sources: nuclear, oil, coil, gas, renewable etc) is about 7.5c€/kWh.

Algora stresses that this record dual-junction solar cell represents a step towards improving the efficiency of triple-junction solar cells, for which the efficiency record of 40.8% was achieved under concentration of 300 suns by the US National Renewable Energy Laboratory (NREL). Researchers in the IES-UPM’s III-V Semiconductors group think that integration of its dual-junction structure into a triple-junction solar cell could result in a device with efficiencies of more than 41% at 1000-sun concentration.

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New, more efficient solar cells patented in Spain

September 23, 2008

3d-photonic-crystal

A team of researchers at the Spanish High Council for Scientific Research (CSIC) has patented a new type of solar cells whose efficiency is up to 30% higher than conventional solar cells. Their photonic crystal is composed of a nanostructured surface which increases the transmission of light inside the device.

CSIC researcher and project leader, Pablo Aitor Postigo, who works at the Institute of Microelectronics of Madrid (IMM-CSIC), points out the advantages of these cells: “They are more efficient in harnessing the sun’s rays. Current systems can only take advantage of 30% of solar energy to convert it into electricity. Our solar cells will enhance the effectiveness of these systems by up to 30%.”

The techniques used by these scientists to produce the crystal can be applied industrially.  The large-scale manufacture of these new solar cells would have the same cost as conventional ones.  In addition, they require less semiconductor material to get the same amount of energy.

Postigo has worked together with several researchers from the Institute of Microelectronics of Madrid (CSIC) and the Solar Energy Institute and the University of Pavia in Italy.

A step closer to a next generation of solar cells

August 9, 2008

In 1997, researchers from of the Instituto de Energía Solar-IES (Solar Energy Institute) in Madrid, invented and patented the concept of intermediate band solar cells as a  way to turn more of the sun’s rays into electricity. After several attempts to develop them,  a group of researchers has revealed the capability of a new material to absorb infrared light. Their work, published in the journal Physical Review Letters, constitutes a new scientific step to reach the implementation of these solar cells.

Conventional solar cells are unable to soak up infrared; that gives them a theoretical absorption limit of just over 40% of solar energy.

In practice, they only absorb about 30%. The new material, though, can harness both visible and infrared photons, so it has a theoretical maximum efficiency of 63%, its creators say.

The performance of intermediate band solar cell (IBSC) relies on finding a way to use more of the solar spectrum. The researchers added titanium and vanadium to get a material that exhibits an intermediate band, half-full of electrons, within what -in ordinary semiconductors- constitutes the bandgap, EG.  The group of researchers was led by Perla Wahnon, from the IES, and Jose Carlos Conesa, from the Institute of Catalysis of the Spanish National Research Council. 

However, while the material’s theoretical absorption limit is 63 percent, that doesn’t mean the finished product would have that efficiency in the real world. Nevertheless, since the theoretical limit percentage is higher, you can also expect a higher real world efficiency percentage. Scientists are already working to develop solar cells made of the new material. 

The Institute of Solar Energy pursues this line of research as part of a European program to extract the most of every single photon available in the full solar spectrum. Through the Professor Antonio Luque, it is the coordinator of the FullSpectrum project, that has reached several interesting milestones and efficiency records in other areas as well, such as multijunction solar cells.

A new flurry of deals in the busy Spanish solar power market

September 22, 2007

These have been busy weeks for deals in the Spanish solar energy market. We saw how WorldWater & Solar Technologies Corp., developer of high-power solar systems, announced an agreement with Prime Solar Senergy, S.L. of Spain. The latter will act as WorldWater’s marketing and logistics partner to acquire and fast-track large scale photovoltaic installations throughout Spain.  WW&ST is also negotiating final contracts with a third company, M&G Promociones, to build three 10-MegaWatt (MW) farms over the next three years  and two additionally planned 50MW farms in Lorca (Murcia Region). WorldWater owns the only patented technology that allows the operation of electric motors up to 1,000 horsepower on solar power alone.

A second operation announced in recent weeks has been the take-over of Panergia, a leading Spanish renewable energy project management and development company, by Epuron GmbH (a subsidiary of Conergy). With this acquisition, Epuron’s project pipeline for large-scale solar power plants in Spain has expanded to a total output of some 150 megawatts. By the end of this year, Epuron will be on the road to complete and connect solar energy projects in Spain that amount to an expected total capacity of more than 20 MW to the public power grid.

But the list does not stop there. Kyocera announced on September 12 it had been selected by Madrid-based Avanzalia Solar, a turnkey solar project developer, as the sole supplier of photovoltaic (“PV”) modules for a super-large-scale solar electric generating system in Salamanca, Spain. The facility, known as Planta Solar de Salamanca, incorporates about 70,000 Kyocera PV modules in three separate arrays 89-acre site.

Planta Solar de Salamanca differs from most other solar electric power plants not only by scale, but also by basic design. Solar PV systems have traditionally been deployed for “distributed” power generation, in which individual homeowners or business owners install their own systems on their own rooftops or immediate grounds. In contrast, Planta Solar de Salamanca was designed as a “central” generating facility to serve a large number of remote users, following the model of more traditional commercial power plants. This design is made economically feasible by the “feed-in” tariff adopted in Spain.

Next week, we are going to be visiting the Solar Power Expo in Long Beach, California, so I expect to be able to report on more bits of news from this ever changing industry.