We discuss and comment on the role agriculture will play in the containment of the CO2 problem and address protocols for terraforming the planet Earth.
A model farm template is imagined as the central methodology. A broad range of timely science news and other topics of interest are commented on.
Wednesday, February 8, 2012
More Efficient Solar Cells
It appears that smart design
configuration has allowed commercial grade solar cells to be produced with real
efficiency in excess of 20% for the first time.Plenty of lab top efforts has been claimed exceeding 20% but never for
rolling of the assembly line.This is
I have always thought that a
consistent delivery of 20% plus efficiency was critical to establishing a solid
economic base to this industry.A loss
of two points at twenty is bad but a loss of two points at 13% is awful.Dust has no problem providing those two
It appears thus that this will
also allow the industry to naturally retrofit upward to a higher power yield.
Innovation and material technology are the keys to success for
increasing the efficiency of solar cells. For the first time ever, scientists
accomplished the development of an industry-scale c-Si solar cell with an
efficiency greater than 20%. The record cell is based on the combination of two
cell design technologies: MWT and PERC.
In a joint research project
with the Fraunhofer ISE, Heraeus has developed a via paste, which interconnects
the front- and back-side of the MWT solar cell. By developing the paste for
Heraeus has made a considerable contribution to its success. Heraeus also
supplied the front-side paste for this project.
What is an MWT-PERC solar cell?
How does an MWT-PERC cell work?
As a crystalline solar cell, the MWT-PERC cell has a silicon wafer at its core.
MWT stands for "Metal Wrap Through".
For MWT cells, the busbars typically found on the front-side of
conventional solar cells, are shifted to the backside of the cell,
thereby reducing front-side shading and allowing more light to actually hit the
cell. The reduction of shading increases the efficiency. The additional
benefit is less paste is required. "PERC" stands for "Passivated
Emitter and Rear Cell".
For PERC cells, the back-side of this cell is designed so that
incoming light is reflected back to the wafer, increasing the amount of energy
captured from the cell. The combination of these two technologies creates a
cell design that significantly increases a solar cell's efficiency relative to
conventional solar cell technologies.
Silver metallization pastes are needed as the initial path for
conducting the energy generated in the cell to the electricity grid. Silver is
the most electrically conductive element in the periodic table and therefore,
is the most widely used component for metallization pastes.
The paste is screen-printed on solar cells and subsequently
incorporated into the cells during a high temperature process. This process is
known as a sintering process. Precisely formulated silver metallization
pastes enable an optimized efficiency gain of the solar cell.
Heraeus offers their customers pastes that are specially formulated to
be used for novel cell design technologies, such as the MWT-PERC-concept.
there is a broad range of different pastes for the front-side and back-side metallization
of conventional crystalline solar cells available. In 2011 Heraeus introduced a
new series of pastes for low temperature processing.