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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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By solarman on 8/18/2008 11:19:42 AM , Rating: 2
Ok I have to interject here. Many here have a good idea of the costs and real meaning behind the efficiencies but are not putting the correct information together to paint a healthy picture of where the industry stands, and what this new cell can do for it.

First of all the average price/watt for solar is $4-$6 so let’s say $5. This is in med to large quantities (i.e. a whole roof or more). The average payback for solar depends on the subsidies you get and the way your LDC (local distribution company) pays you for the solar (if at all). Some will net-meter and pay you only when you use negative energy (i.e. you are pumping out more from the panel than in). This will not help with payback periods. Some places will not net-meter and will pay you for the total output of your panels regardless of what you are using (i.e. a separate contract that does not involve the previous one for electricity usage).

But, the industry is almost completely large scale applications, in areas where the total VALUE of the electricity generated by solar (PV, CPV, CSP, SWH) is high enough to counter the actual dollar value which at best pays back in 15-20 years for PV, and about 0.6 to 1/2 that amount for CPV, and even less for CSP.

These cells in this article refer to 300+ suns because they are designed for CPV (Concentrating PhotoVoltaics) which use reflectors or mirrors or lenses (Fresnel) to concentrate the light by up to 500 suns!

Cells that are already 35% or more in efficiency at 500 suns do not need liquid cooling, and those companies wise enough to incorporate liquid cooling will have found a great source of SWH (solar water heating) which increases the value of their investment and decreases their payback period significantly, and thus increasing the total efficiency of the panel to beyond 40%.

Get real, do your homework, and make money off this industry. Plain and Simple.

RE: Whoa
By 67STANG on 8/18/2008 3:46:22 PM , Rating: 2
I agree with most of what you say. I was paying around $4.30/watt buying in bulk....

The biggest problem I've found with solar is that the hotter tha panel is, the lower it's efficiency gets-- that's just the way it works.

Another issue I see is that residential solar doesn't always pay back. I don't know a lot of people that stay in their house for 15-20 years. (Americans move an average of every 5 years). That means you have to hope you can upsell your house to make any extra money. If you are building your dream home that you plan on keeping for quite some time, then I can see it paying back-- assuming you have the upfront capital to invest.

Unfortunately with Europe (especially Germany) swallowing up many of the 160w and up panels, it really drives up the price for use "poor" Americans-- especially with our weakened dollar. What the solar industry really needs is more mass production-- something that it has been lacking since its birth. Cheaper materials wouldn't hurt either, much like the "CIGS" developed in South Africa. I wonder if they've began making those 1,000 panels a day they promised over 2 years ago.

RE: Whoa
By IReviewer on 8/18/2008 3:52:11 PM , Rating: 2
Metering may be needed most places since as with wind-power, fluctuations in supply to the grid can have adverse affects. Not certain where the control would need to be since wind-farms represent large units. Net-metering could be delayed by this factor.

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