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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 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.

"And boy have we patented it!" -- Steve Jobs, Macworld 2007

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