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Mitsubishi Electric Achieves 18% Conversion Efficiency in Multi-Crystalline Silicon Solar Cell

Mitsubishi Electric announced it has achieved a photoelectric conversion efficiency rate of 18.0% in a 150mm square practical use multi-crystalline silicon solar cell, an improvement of 1.2% over previous models and the world’s highest rate to date. The company plans to present its technology at the Fukuoka 17th International Photovoltaic Science and Engineering Conference in December 2007.

To achieve the 18% rate, Mitsubishi added a low reflectivity surface texture on the multi-crystalline silicon, developed a process to print electrodes on the surface of the silicon (metallization) and reduced shade loss of the front grid electrodes. In the same surface area as previous products, the company achieved a 7% greater electric output, making the new cells suitable for small installations such as narrow roofs.

Main features of the cell include:

  • Increased light absorption using a unique Reactive Ion Etching (RIE) method. Using a nano-sized mask material, the RIE method uses highly reactive ions generated by RF plasma, letting ions precisely etch the target materials. This decreases reflectivity from the texturized surface of the multi-crystalline silicon, increasing the amount of absorbed light. This process is based in part on the result of the NEDO (New Energy and Industrial Technology Development Organization) project for R&D of innovative next-generation photovoltaic system technology.

  • Suppresses reduced electrical performance in crystalline. New metal electrode material reduces metallization time by approximately half that of previous models, and sustains electrical performance of crystalline.

  • Expanded effective electrical output surface area. Using modified screens and front metal electrodes, Mitsubishi reduced shading loss of front grid electrodes by 40% compared with its conventional cells.

The company will begin introducing this technology into mass-produced photovoltaic modules after the end of 2007. Pairing this with Mitsubishi’s power module, which has the industry’s highest energy conversion efficiency (PV-PN04F: 95.5%, PV-PN06F: 95.0% as of 31 May 2007) will increase output of solar power systems.

Comments

doggydogworld

Stan said:

"Now someone else projected that all the energy needed, could be supplioe by tiling only a paltry .1% of the ground. Sorry your decimal points are way off."

The actual claim was all electricity (not all energy) would use 0.5-1.0% of desert area. But 0.1% of total land area is not far off. In the US Southwest each square meter of these 18% efficient PV would produce about 400 kWh/year (1 kW/sq meter peak insolation * 18% efficiency * 6+ hours peak insolation per day * 365 days/year). US electric generation is 4 trillion kWh/year. So you need 10 billion square meters which is 10,000 sq km. That's 0.11% of the US's 9.2 million sq km land area.

Of course the idea of getting 100% of electricity from PV is silly, it's just an exercise to demonstrate how little land PV requires. US parking lots cover more than 10,000 sq km and US roofs cover more than twice that. US highways cover over 60,000 sq km of land.

--ddw

Tom

Ooo ... so that means to combat global warming we could just coat large sections of the existing desert with tin foil! This would lower the albedo and BOOM ... no more global warming!

Seriously ... roofs are already dark. Putting solar cells on them will not significantly alter the global temperature and will probably generate an appreciable fraction of required energy for a building.

Covering the desert with solar panels may have some unintended environmental impacts which have nothing to do with albedo. It might look like just plain sand but its a fragile eco system just like any other. You might want to think more carefully about minimizing that impact rather than dwelling on how the solar cells will warm everything up ... at least on a global scale to start with.

sjc

In the Mojave, you have more than 100 miles by 100 miles of nothing but desert.

10,000 square miles and you cover maybe 100 square miles or 1% with solar cells.

That would cost a fortune, but covering 1% of the Mojave would not even effect the thermal air currents that much.

swen

Desert schmesert. If it were possible just for everyone to put PV on their own roof, that would take care of most of the electricity needs. PVs got to be cheaper to be more attractive, bottom line. Germany's government has a better program that makes it easier for a wage earner to afford
PV with generous subsidies. Germany has come a long way
to energy independence while we twiddle our thumbs. My
dream is to have PV on the roof and a PHEV plugged into
it. If only I could afford it, I'd do it in a snap. $20-$30k is out of my reach.

sjc

Lots of people do not like the looks of PV panels on peoples roofs. To get any significant percentage of electricity from PV, lots of roofs have to have lots of them.

Clinton had the million solar roof program that is still going to try to achieve the goal. There are over 50 million single family homes in the U.S...you do the math on how effective this can be and how soon.

sqch

let's take all the money (billions?) we spend on invading/occupying oil countries and invest it in our future buy subsidizing American made solar cells to make them cheap enough for everybody to afford. once economy of scale takes over, we will rule the world (in solar cell production)

a hippie friend of my father back in the day tried to get the government to put options on our tax return for how we want our tax money to be spent. I'll invest in PVs instead of morgue fodder!

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