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The future of solar is looking much brighter

Solar power is taking off around the world.  Europe is planning to deploy various types of solar power to the Sahara to provide for the European Union's energy needs.  Meanwhile, here in the U.S., California is expanding its solar efforts as well.

However, amid the progressing adoption of solar technology, one perpetual criticism that persists is that solar power is inefficient and expensive.  To some extents this is true.  The current generation of photovoltaic solar panels -- the type of solar power perhaps most associated with the field -- is only around 20 percent efficient and thus costs remain relatively high, like many forms of alternative energy.

A new breakthrough from U.S. Department of Energy's National Renewable Energy Laboratory (NREL) is looking to solve those problems.  It pushes solar cells to uncharted technology with a record 40.8 percent efficiency.  The new work shatters all previous records for photovoltaic device efficiencies.

The researchers first used a special type of cell, an inverted metamorphic triple-junction solar cell.  The custom cell was designed, fabricated, and independently measured at NREL.  The next step was to expose the solar cell to concentrated light of 326 suns, yielding the record-breaking efficiency.  A sun is a common measure in the solar power industry which represents the amount of light that hits the Earth on average.

The new cell targets a variety of markets.  One potential market is the satellite solar panel business.  Satellites natural absorb more intense sunlight, thanks to no atmospheric interference.  Another possible application is deployment in commercial concentrated PV cells.  Concentrated PV is a burgeoning field, with several companies currently contracted worldwide to build the first utility grade plants.

The new record was welcome news, but little surprise at NREL -- they held the previous record as well.  In order to beat their old design, one key was to replace the germanium wafer at the bottom junction with a composite of gallium indium phosphide and gallium indium arsenide.  The mixture splits the spectrum into three parts, each of which gets absorbed by one of the junctions.  Both the middle and bottom junction become metamorphic in the new design.  This means their crystal lattices are misaligned, trapping light in the junction and absorbing more of it.  This yields an optimal efficiency.

One key advantage is the new solar cell can be conveniently processed by growth on a gallium arsenide wafer.  It is also both thin and light.  The NREL believes this cell will be cheaper than current commercial models, while delivering far more power.

Some of the credit for the work goes to NREL's Mark Wanlass, who invented the cell's predecessor.  The new cell was redesigned by a team led by John Geisz.

The NREL is operated by the DOE by Midwest Research Institute and Battelle.

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RE: No big deal
By JasonMick on 8/18/2008 9:56:04 AM , Rating: 4
If cars followed the same path we'd still be driving Ford Model Ts.

What are you talking about?

In 1908 the Model T was released with a fuel economy of 17 miles per gallon city. Today, the Toyota Camry gets around 22 MPG city. The top speed has certainly increased greatly, but the efficiency has not.


If you compare solar to the auto industry:

1 percent to 40.8 percent --> 4,080 % increase in efficiency

17 MPG to 22 MPG --> 29.5 % increase in efficiency.

I think the winner is pretty clear, on the contrary to your remarks.

RE: No big deal
By ebakke on 8/18/2008 10:17:22 AM , Rating: 2
There are far more things involved with automobiles than purely fuel economy. Interior comforts/luxuries, storage space, towing capacity, safety features, etc. To make the insinuation that today's Toyota Camry is only marginally better than a 1908 Model T is asinine.

RE: No big deal
By nah on 8/18/2008 10:31:17 AM , Rating: 5
There are far more things involved with automobiles than purely fuel economy. Interior comforts/luxuries, storage space, towing capacity, safety features, etc. To make the insinuation that today's Toyota Camry is only marginally better than a 1908 Model T is asinine.

That may be correct--but you haven't looked at the other side of the equation--what was the price of a Model T in 1908--around USD 850, which, when adjusted for inflation is around USD 18,000 today--not much lesser than a Camry, while offering much fewer benefits. In contrast, the price of a solar cell has fallen by almost a hundred times (10.000 % ) over the last fifty years--while improving (in average efficiency) over 400%. Comparing between industries is moot--has the healthcare industry improved as dramatically as the IT one ? As someone said, if cars advanced as fast as processors a Rolls Royce would cost about USD 15, be more powerful than a train, could go around the world 2500 times on a tankful of petrol,and be so small that 6 could be parked on this full stop. Needles to say--it's only passengers would be microbes, or high ranking bacteria ;)

RE: No big deal
By ebakke on 8/18/2008 12:40:36 PM , Rating: 3
Sure, but you're comparing the first mass produced automobile to the first produced solar cells.

Comparing between industries is moot

I agree wholeheartedly that cross-industry comparisons provide little benefit. In fact, that was my whole point.

RE: No big deal
By blaster5k on 8/18/2008 10:44:54 AM , Rating: 2
That's not even close to a fair comparison. The efficiency of the engines themselves is much better today. They last much longer. The performance is much higher. Way more safety features and creature comforts are in the cars themselves. Emission controls didn't even exist on the Model T. Modern ULEVs and PZEVs emit next to nothing.

The curb weight of a Model T is 1,200 lb. The Camry you mention is 3,300 lb. Obviously the extra weight is a factor in this particular comparison. Of course, some of that extra weight is necessary just to meet emissions and safety standards that exist today.

RE: No big deal
By JasonMick on 8/18/2008 10:53:24 AM , Rating: 5
Entirely, correct, my point was not to provide a fair comparison, just to point out that

A) Comparing solar cells and cars is comparing apples and oranges.


B) To knock any field for *only* increasing its efficiency by 4000+ percent over 100 years is ridiculous.

Obviously cars today have advanced greatly since the days of the Model T, but its very subjective to try to say what has advanced more in that time period, cars or solar power.

RE: No big deal
By masher2 on 8/18/2008 12:55:18 PM , Rating: 5
> "The top speed has certainly increased greatly, but the efficiency has not."

Jason, please stop spreading FUD. The original Model T weighed about 1,200 pounds and had only a 20 hp engine. It lacked not only all the safety featured mandated by thousands of DOT regulations, but also the vast amount of emission reducing controls, which also reduce mileage. It ran on a leaded non-oxygenated, non-reformulated, non-ethanolized gasoline that offers substantially higher MPG than the blend sold today. Finally, the MPG testing requirements today are far more stringent than those originally implemented a hundred years ago. Just the difference in testing alone can account for a 40% margin.

A modern car engine itself is far more efficient than one from 1915. Strip the emissions controls off a Camry engine, put it in a lightweight Model T, and run it on the same non-oxygenated gasoline, and you'll see city mileages about three times higher than the original engine would receive. Given the basic Carnot efficiency limit on any heat engine, that's an extraordinary increase.

RE: No big deal
By goku on 8/18/2008 4:50:19 PM , Rating: 2
Wrong, they did not have leaded fuel until the 1930s. Also about the price of the model T, it got down to around $300 per car in the mid 1920s so it was a very very cheap car by the time the 1920s rolled by. Also the model T could run on 100% ethanol or gasoline so there was no need for leaded fuel, leaded fuel was added later on as a cheap octane booster for lower quality fuels.

RE: No big deal
By masher2 on 8/18/2008 7:22:43 PM , Rating: 2
> "Wrong, they did not have leaded fuel until the 1930s."

Sorry, but ethyl leaded gas was first sold in 1923:

> "Also the model T could run on 100% ethanol "

Sure. And it would have gotten about 30% less mileage as a result. It would get about 4% less mileage running on today's gas oxygenated with 10% ethanol. The point is valid.

RE: No big deal
By ZmaxDP on 8/18/2008 5:31:20 PM , Rating: 2
FUD huh?

I'm bothered by the implication that somehow efficiency is what drives the value of photovoltaic panels. Unlike other energy sources, we aren't charged for the amount of sun falling on our roofs. So, efficiency is not all that important once past a certain threshold. What might that be? The point at which the surface area available for collection provides enough energy to meet your demand. Efficiency is already at a point where you can power a home from significantly less than 100% of your roof area. For commercial buildings or power generation purposes, efficiency is more important (much higher demand for a given surface area - duh).

The problem currently is one of price/kW. Because of the high price of panels, it takes too long in most markets to get a full payback. So, people don't do it.

Unfortunately, I'm not fully aware of the costs that go into making solar panels, so I have no idea why they are at their current price point. Typically, increasing the volume of a manufactured good decreases the price to produce it. If such an increase could result in a net decrease in cost of 50%(ish) you'd see a very different reality. Alas, it's all "what if" until it happens...

RE: No big deal
By theapparition on 8/18/2008 7:54:43 PM , Rating: 2
Efficiency is already at a point where you can power a home from significantly less than 100% of your roof area.

First off......what's signifigantly less. 50%? 30%?

Second, there is no way you can completely power an average home strictly from solar power. Even in the best latitudes, homes that barely make a surplus from the day require far more than that surplus to use at night. Plus you have to factor in weather and cloud cover.

Notice I say average home, I'm sure you'll find some eco-freak who runs an exercise bike at night to power his TV and doesn't draw from the grid, but the average home will require being hooked to the grid, even if they had 125% coverage.

RE: No big deal
By fic2 on 8/18/2008 7:10:35 PM , Rating: 2
Interesting that you compare a one off/laboratory solar cell to a mass produced commercially available car. Why not compare most efficient in the world solar cell to the most efficient in the world car? That would be the Microjoule getting 8,923 miles per gallon (as far as I could find).

In that case your auto goes from
17 MPG to 8923 MPG --> 52,488% increase in efficiency
somewhat better than your 29.5%

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