Tuesday, May 26, 2009

European photovoltaic research project achieves new world record in efficiency

Researchers of the European funded project CrystalClear have successfully developed innovative technologies for silicon solar modules to be manufactured at €1 per watt-peak of power. Moreover they have achieved world-record efficiencies for modules with multicrystalline silicon solar cells. Their full-size solar modules have achieved a premium aperture area conversion efficiency of 16.0 to 16.4%.

The previous world-record was held by Sandia National Laboratory (USA), at 15.5% aperture-area efficiency. This means that the main project target of reducing the costs of PV modules by more than 50% (if produced in large volumes) has been achieved.

Solar energy and especially photovoltaics are a growing source of electricity in Europe. Thanks to research the European photovoltaic (PV) sector has developed strongly. One of the main research goals is increasing the conversion efficiency from sunlight to electric energy and reducing the manufacturing costs of solar modules and systems.

Such cost reduction is an important condition to reach grid parity; the point at which the generation cost of electricity produced by PV systems equals the retail price of electricity from the grid. The Commission funded the project CrystalClear with € 16 million (total budget € 28 million). The European Commission supported development in this field with approximately €105 million as part of the 6th Framework Programme for Research. In the first two years of FP 7 the Commission has already signed contracts for PV projects amounting € 46.8 million. For this year approximately € 10 million will also be allocated.

The low-cost technologies developed in the consortium are all characterised by the use of very thin silicon wafers, advanced solar cell designs and processing, innovative module assembly, and high efficiencies. An important common feature is the very effective reduction of conversion losses that normally occur at the surfaces of the cells.

The world record was achieved using industrial-scale equipment for interconnection and encapsulation of rear-contact cells. The new module design and manufacturing process is based on interconnection of the cells using conductive adhesives and a patterned conductive foil. The 16.0% efficient module was built with 36 cells of 120 micron thickness only (the 16.4% module had 160 micron cells), much thinner than the 180-200 micron thickness used by industry. All modules were made without any cell breakage, underlining the potential for cost reduction and the feasibility for use in production

Last year scientists of the Commission-financed project Fullspectrum were successful in developing photovoltaic multi-junction solar cells with an efficiency of 39.7% under concentrated sunlight. These multi-junction solar cells are very expensive per unit area and are therefore aimed for use in concentrator PV modules and systems. In such systems sunlight harvested on a certain area is focused onto a much smaller area solar cell. Similar cells are also used in space and on PV driven racing cars.


Background

Energy research is constituent of the European Union Energy and Climate Package. One of its ambitious targets for 2020 is to increase by up to 20% the level of renewable energy in the EU's overall final energy consumption. To reach this goal the European Commission started the Strategic Energy Technology (SET)-Plan.

The Solar Europe Industrial Initiative as part of the SET-Plan has recently elevated its target for the share of photovoltaics in the European electricity demand by 2020 from 3% to 6% or even 12%, if conditions are favourable and suitable measures are taken. This can be translated into installing up to 400 gigawatt-peak (GWp) capacity of photovoltaic systems, corresponding to an average growth of ~40% per year from today's situation.

Between 2001 and 2007, installations of photovoltaic systems in the European Union increased more than ten times and reached 4,7 GWp cumulative installed capacity at the end of 2007. Most of the EU 27 PV installations are in Germany. Despite the fact that the European PV production grew again by almost 60 % and reached over 1 GWp, the huge German market demand did not change the role of Europe as a net importer for solar sells and modules.