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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.



This is good news. Multi-crystalline cells are easier and cheap to manufacture than mono-crystalline, but have been less efficient. There is a good program on PBS NOVA called "Saved by the Sun" that explains the various solar technologies.

Stan Peterson

Another great
Global Warming method. It absorbs 18.5% MORE than the perfect Black Body absorber/radiator. In effect it is blacker than the balckest black, and great at absorbing 18.5% MORE of the incipient radation than any natural surface.

Can't think of a thing more prone to increase global warming. Widespread adoption would reduce the Albedo creating more Sahara deserts.

The Society for the Prevention of Albedo Reduction in the US, S.P.A.R.E. U.S. rejects this global warming enhancer. (unless global warming is not really a problem).



You really need to seek professional help...soon.


Wait Stan can you explain this: how can you absorb 100%+18.5% (118.5%) of the incident light?

If increasing the earth's albedo bothers you, you should attack asphalt road construction not solar panels.

Roger Pham

Only .5%-1% of desert will be needed to provide enough electricity to replace current demand, displacing gazillion tons of CO2 emission by fossil-fuel power plants. Even if solar cells can absorb 100% of incident solar irradiation, 18.5% of that is turned into electricity, thus only 81% of solar energy will be turned into heat. Sandy surface already absorb over 1/2 of solar irradiation. So, an increase from 50% to 80% of an area under 1% of total area will be negligible.
But, the massive amount of CO2 emission displaced by solar panels, if widely deployed, will have a significant effect on reduction of global warming!


Roger! Great post ... and you did it without using the word "hydrogen" even once :)



Right on. Low cost PV is the potential game changer.


Problem: sun is only out at day, production is only optimum on cloudless days. To replace all conventional electric power with solar you would need many times the maximum needed wattage in panel area and a means of storing and delivering the power for the night and during peak load. You would also need a efficient means (more efficient then power lines) of transporting the electricity from the desert thousand of miles away.

Paul Dietz

It absorbs 18.5% MORE than the perfect Black Body absorber/radiator.

Apparently the first law of thermodynamics doesn't hold in your universe, Stan.


Total question of curiosity....
What is the electrical output of the average nuclear reactor? What is the acreage used to support the facility? And for comparison, if that same acreage was filled with solar panels, how close would it come to matching the output of the reactor (assuming the sun is shining). I'm under the assumption we'll need both, going forward, but I'm curious about the comparison.


To produce 18 KWh of electricity PV will adsorb less than 100 KWh of solar energy, while coal-fired power plant will burn more than 50 KWh worth of coal to generate 18KWh. Makes PV panel less heat-dissipating than desert sand with 0.5 albedo + coal-fired power plant, let alone roof-tops where most likely PV will be mounted.

If increasing the earth's albedo bothers you, you should attack asphalt road construction not solar panels.
Attack green plants. It's the Intelligent Design of chlorophyl to absorb radiation.

"Intelligent design of Chlorophyl"
Awesome line.


I do not think anyone is saying that you can replace all electric generation with solar PV, but you can run a lot of ACs with it in the summer. We have SO much desert land in S Cal, that the land usage is not a major factor, the cost per watt installed is.


Exactly. Electric usage peaks in the hot sun. It makes since that the difference between peak usage and night usage should be filled by solar, with the baseline power as nuclear or clean coal.


with all the electric cars which will be connected to the grid you will have a great storage for electricity!!

W Newey

Absorb the heat with water then use the hot water Did I miss something?


W Neway - "Absorb the heat with water then use the hot water Did I miss something?"

Or better yet absorb the heat in molten salt or ammonia. Future concentrating solar power plants will do this.

I think that CSP is better for very large scale solar with PV really good for household or business roof mounted power. We will need both for renewable grid.


Strangely enough solar power isn't strictly limit to daytime. Heat differential towers can generate electricity at night from heat already stored in the ground. Solar concentrators can store heat during the day in melted salts. PVs ... that's another story.

Stan Peterson

Some of you really need a little technical training. Listening to the Greenie's crayola level and view of physical laws, is not healthy for you.

The best passive absorber/radiator conforms to the thermal radiative profile and is proportional to T**4.

Any passive device absorbs incident radiation until an equilibrium is reached and then re-radiates any additional input in a thermal profile. But a PV solar panel is not s "Passive" device at all. It absorbs incident radiation and converts some of it to electrical energy, and then moves that electrical energy to somewhere else via a current flow, moving the energy. This being so, an active device can absorb MORE incident radiation then the very best passive device. The ratio of what the maximum that a passive device can do, and what an active device can do, is the ratio of amount of Energy converted and moved, to the maximum passive radiation possible to be absorbed at equilibrium.

And yes asphalt roads do indeed change the Albedo. Please Ggoogle the Heat Island effect of cities in altering the local climate and temperature profile.

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.

Please provide me a reference for that assertion, because any back of envelope calculation indicates tiling an area at least as large as several states to accomplish that objective (Nevada, Utah, and Arizona)killing and cooking anything there in.

Speaking of asphalt, the EPA purposely turns a blind eye and calls asphalt a non-polluter although it is a source of lots of evaporated pollution-type hydrocarbons. You've all seen it. Square miles of heavy hydrocarbons layed on the ground, baking in the sun, evaporates its volatile fractions, "drys out" and cracks up.

Once upon a time the Greeens said that natural recyclable energy sources were better. Then windmills ruined the view, so we suddenly we heard complaints that they chiopped up birds. Thenn hydroelectric power was clean and renewable, until some clucks wanted to run white water expeditions, or go river fishing, and now hydrelectric power is a Greenie no-no. Once upon a time geothermal energy conversion was a great renewable, until stink from thermal ventin,g bothered some people; now that is no longer a Greenie option.

I said in 1970, and even created an enviro group to say that, extensnive and widespread Solar energy is dangerous to the environment. If we ever really have to use it, I'm sure the Green loons will discover the warts that are there in any technology. Widespread solar has many, many, warts.

tom deplume

I'll take solar energy's warts any day over fossil fuel's malignant tumors. Compared to global warming concerns about birds, fish, nuclear waste, and spoiled scenery are trivial.


OK Stan, you convinced me: when I’ll install PV on my roof I’ll alternate PV panels with strips of bare aluminium.

But seriously, what is the difference where adsorbed visible light will be re-radiated as IR: from PV itself or from light bulb it will run (or heated by light bulb air)? As I understand it, it is “albedo” of the surface in visible light frequency which defines Earth energy balance; any adsorbed energy will be re-rediated as IR one way or another.


I have a GW question. We've all been discussing the greenhouse effect of CO2. What's been the effect of just taking all that fossil fuel out of the ground year after year and burning it. Is that enough BTUs to make a difference? I'm too lazy to do the calcs myself, does anyone know if the calcs have been done elsewhere?


Neil, look up "thermal pollution".

Paul Dietz

This being so, an active device can absorb MORE incident radiation then the very best passive device.

Nonsense, Stan. Your misconceived idea violates conservation of energy. It is obviously wrong.

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