Archive for January 3, 2012

Mapping Solar Grid Parity

Here is a great interactive map that shows when Metropolitan areas in the US will achieve grid parity.

Mapping Solar Grid Parity

TVA begins the new year with one third of its board seats vacant

By Dave Flessner Chattanooga Times Free Press
Published Monday, January 2, 2012
When Congress adjourned on Christmas Eve, three of TVA’s most senior and active board members left the agency’s 9-member board. President Obama has yet to nominate any successors to fill the three vacancies.

Three retired bankers — former TVA Chairman Dennis Bottorff of Nashville, former TVA chairman Mike Duncan of Kentucky and TVA Director Tom Gilliland of Blairsville, Ga., — ended their TVA employment at the end of the year after their normal terms had already expired in May.

Under the TVA Act, directors may stay until their successor is confirmed or until the end of the congressional session in the year in which their terms end.

Bottorff, who succeeded Duncan as TVA chairman in 2010, gave up the chairmanship in November to Knoxville businessman Bill Sansom.

The only remaining TVA board appointment by former President George Bush is Memphis Bishop William Graves, whose term ends in May.

TVA directors are appointed by the president and confirmed by Congress for rotating five-year terms.

Sharp develops solar cell with world’s highest conversion efficiency of 36.9%

The major breakthrough of the year hands-down has to be Sharp’s novel tandem cell which measured the highest non-concentrating conversion efficiency measured to date.

After eleven years of research and development, Sharp Corporation has achieved the world’s highest solar cell conversion efficiency of 36.9% using a triple-junction compound solar cell in which the solar cell has a stacked three-layer structure. Measurement of this value, which sets a new record for the world’s highest non-concentrating conversion efficiency, was confirmed at the National Institute of Advanced Industrial Science and Technology (AIST).

Compound solar cells utilize photo-absorption layers made from compounds consisting of two or more elements, such as indium and gallium. Due to the high conversion efficiency, compound solar cells have been used primarily on space satellites.

In 2009, Sharp succeeded in improving cell conversion efficiency to 35.8% based on proprietary technology that enabled efficient fabrication of a stacked triple-layer structure with InGaAs (indium gallium arsenide) as the bottom layer. This latest increase in conversion efficiency was achieved by improving the maximum power output of the solar cell by reducing the resistance of the junction areas necessary to connect the solar cell layers in series.

Japan’s New Energy and Industrial Technology Development Organisation (NEDO), which promotes research and development as well as disseminating industrial energy and environmental technologies, aided this breakthrough.

In the future, processes for transferring ultra-thin PV layers onto film substrates will make lightweight, flexible solar cells possible.

Mapping Solar Grid Parity

Solar grid parity describes the moment when electricity from solar power is less costly than electricity from the existing grid.  It’s a tipping point, when democratization of the electricity system not only makes political and economic sense, but becomes more competitive than using utility-delivered electricity.

We used the following assumptions in the construction of this animated map:

  1. The cost of solar in 2011 is $4.00 per Watt installed.
  2. Grid electricity price is the average residential retail rate reported by PVWatts for the core city of the metropolitan area.
  3. The cost of solar decreases by 7% per year.
  4. The grid electricity price increases by 2% per year.

In just 7 years, 1 in 6 Americans living in major metropolitan areas could lower their electricity bill by installing solar –without any incentives. Here comes the sun!

Animated Map


A novel system that could convert 37% of sunlight into electricity

The goal at the end of the rainbow is to capture the pot of gold. In the case of solar PV, it is to increase the efficiency of light-to-electricity conversion. A scientist at MIT, Dr. Peter Bermel has a totally new concept of increasing the conversion process. He and his colleagues have invented a way of concentrating the energy in the sun’s rays without the need for mirrors. It is, quite literally, a suntrap. Their concept has been published in in Nanoscale Research Letters and is had to describe. The following is a story taken from The Economist dated December 31, 2011.

Dr Bermel’s proposed trap is a thin sheet of tungsten (a heat-resistant metal) that has been processed in quite a complicated way. One surface, which faces the sun, is covered in microscopic pits. The other, which faces a specialized type of solar cell made of a material called indium gallium arsenide, is sculpted into a structure called a photonic crystal that causes it to emit infra-red radiation selectively at the frequency best absorbed by the cell. Both of these surfaces would be created by photolithography, the process used to make computer chips. According to Dr Bermel’s calculations, would be a system that converts 37% of sunlight into electricity. This compares with a maximum of 28% by standard silicon-based solar cells that have not had the incident light concentrated by parabolic mirrors.

full story