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June 01, 2007

Solar cells with 40.7% efficiency made, 58% efficient possible

Scientists from Spectrolab, Inc., a subsidiary of Boeing, have recently published their research on the fabrication of solar cells that surpass the 40% efficiency milestone—the highest efficiency achieved for any photovoltaic device.

A pdf with levelized cost of electricity analysis for natural gas, coal and nuclear from 2006
Natural gas is 3.8 to 5.9 cents(US)/kwh
Coal is 3.5 to 4.4 cents(US)/kwh
Nuclear is 2.5 to 4.1 cents (US)/kwh

The goal of the Solar America Initiative (SIA) is get solar energy competitive with other energy sources. How do the exact costs for Concentrated Solar Power (CSP) actually compare to other energy sources ? First, I will review the newest solar cell breakthrough in a bit more detail. Second, I show some references that compare costs of energy sources. Costs for all energy sources have a fairly large degree of variability based upon factors such as project financing (interest rates), local variables, project variables such as differences in labor and material costs. This variance is not dealt with in most analysis of costs. After the initial first pass comparison of costs, I look at some of the variables related to nuclear power costs. I have another source for hydroelectric cost (only China since that is where most new hydroelectric is being built) and then more CSP cost details.


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In the design, multijunction cells divide the broad solar spectrum into three smaller sections by using three subcell band gaps. Each of the subcells can capture a different wavelength range of light, enabling each subcell to efficiently convert that light into electricity. With their conversion efficiency measured at 40.7%, the metamorphic multijunction concentrator cells surpass the theoretical limit of 37% of single-junction cells at 1000 suns, due to their multijunction structure.

The Spectrolab scientists also predict that with theoretical efficiencies of 58% in cells with more than three junctions using improved materials and designs, concentrator solar cells could achieve efficiencies of more than 45% or even 50% in the future. [This will enable costs to reach 4-5 cents per kwh in the better locations for solar power (see the map of sunlight levels at the bottom).]

The research that led to the discovery of the high efficiency concentrator solar cell was funded partly by the U.S. Department of Energy’s National Renewable Energy Laboratory, and will play a significant role in the government’s Solar America Initiative, which aims to make solar energy cost-competitive with conventional electricity generation by 2015.

Citation: King, R. R., Law, D. C., Edmondson, K. M., Fetzer, C. M., Kinsey, G. S., Yoon, H., Sherif, R. A., and Karam, N. H. “40% efficient metamorphic GaInP/GaInAs/Ge multijunction solar cells.” Applied Physics Letters 90, 183516 (2007).



The Levelized Cost of Electricity calculated by Sandia Labs (1997 dollars)


Another look at Levelized cost of Electricity (2005 dollars)

For China which is adding 160 GW of hydroelectric power over the next 12 years, the cost of hydroelectric is 0.25 yuan per kwh This converts to USD$0.019 per kWh or 1.9 cents (based on 7.66 yuan to 1 USD.


Varying cost estimates for nuclear, from the Economics of Nuclear Power by Steve Thomas

Another source of nuclear energy costs compared to other energy sources

The DOE has not set specific SAI program targets for domestic installed PV capacity or manufacturing capacity, but the program estimates that total installed PV capacity may reach 10-15 GW in domestic markets by 2015, if the SAI catalyzes cost reduction to parity with the grid by 2015.

Here is PDF with the funding opportunities from the SAI program


On page 13 of the 14 page pdf, they describe the performance parameters that they are using to measure progress.


Here is Sandia National Labs survey of Concentrated solar power


History and Projection of CSP costs. Concentrating solar power technologies currently offer the lowest-cost solar electricity for large-scale power generation (10 megawatt-electric and above). Current technologies cost $2–$3 per watt. This results in a cost of solar power of 9¢–12¢ per kilowatt-hour. New innovative hybrid systems that combine large concentrating solar power plants with conventional natural gas combined cycle or coal plants can reduce costs to $1.5 per watt and drive the cost of solar power to below 8¢ per kilowatt hour.

Advancements in the technology and the use of low-cost thermal storage will allow future concentrating solar power plants to operate for more hours during the day and shift solar power generation to evening hours. Future advances are expected to allow solar power to be generated for 4¢–5¢ per kilowatt-hour in the next few decades. This is towards the high end of mainstream power sources but would be competitive in many areas as costs fluctuate depending upon location. Also, the costs of fossil fuel power sources seems likely to increase.


Different CSP types compared from the Sandia Solar thermal technologies overview document


Solar resources in the USA.

1 comments:

solar power said...

It's a great discovery and I'm sure it will help to use solar power effective. I think that this is a good start for the idea of a technology that can be improved with an excellent promising future. Because if we can use the sun as a source of energy for a cleaner and healthier environment why not use it. And by the way the entire earth will thank to those innovative people.