Solar Hyper-Concentrators: Reducing The Cost of Solar Power
by Justin Thomas, Virginia on 08.12.06
Focusing the sun a myriad times — that's the aim of solar hyper-concentrators. These devices focus high intensity sunlight on a small area, usually with Fresnel lenses or mirrors. The newest concentrators are a competitive power source, rivaling other up-and-coming renewable energy systems. Some devices are capable of achieving a sunlight concentration equivalent to hundreds of suns.
The Stirling Solar Energy technology (see above) converts thermal energy to electricity by using a mirror array to focus the sun’s rays on the receiver end of a Stirling engine. The internal side of the receiver then heats hydrogen gas, which expands. The pressure created by the expanding gas drives a piston, crank shaft, and drive shaft assembly much like those found in internal combustion engines but without igniting the gas. The drive shaft is connected to a small electricity generator. The entire energy conversion process takes place within a canister the size of an oil barrel.
Two other companies with solar concentrator technologies are Solfocus and Entech.
Entech has a patented concentrator technology which allows for the installation of massive solar "farms" with reduced requirements for solar cell materials (silicon or multi-junction).
Due to the advantages of Entech's concentrator, only 5% of the amount of silicon used in flat plate solar modules is required by current Entech modules to generate the same electrical power. For example, 50 kilowatts of solar cells used in conventional flat plate solar modules generates one megawatt of electrical energy using the Entech modules. Entech concentrators utilize a two-axis tracker to follow the sun's position throughout the day, maximizing energy production.
The funding at SolFocus, which complements a seed round of $3.5 million in March, will be used to test and ramp up production of SolFocus' concentrators and to hire more people, said Gary Conley, the company's founder and CEO. Nanosolar, has raised about $100 million to build a plant to make solar cells from CIGS (copper-indium-gallium-selenium). SolFocus' concentrators magnify the light 500 times, which Conley called the "sweet spot" between higher energy production and excessive heat. The products are aimed at the commercial market, such as retail stores or office parks. SolFocus also intends to build large-scale power generation, where a field of panels could generate several hundred megawatts of power, Conley said.
The company intends to have a 100-megawatt manufacturing facility in India operating at the end of next year, he said. SolFocus then intends to replicate that plant in China, Europe and somewhere in the Americas.
Except that Nanosolar is going to produce inexpensive, flexible photovoltaic panels, not concentrator systems. Very promising stuff, though.
Concentrator systems are usually used with more expensive (but higher efficiency) solar cells.
Show me the money: cost, cost, cost.
This post is a confused jumble of information. This type of confused presentation is a disservice to those trying to understand these technologies!
This article misses the point of why Solfocus is using a concentrator (to make photovoltaic cells more effecient and cost effective) or that the Solfocus panel is a flat, modular panel that looks much like a regular photovoltaic panel.
The big reflecting concentrators shown in the photo are used to create high heat to power a stirling heat cycle engine.
If the point is to discuss concentrator technology is general, why not point to a site where the topic is given balanced, accurate and complete coverage, so people are informed, not confused by the mixing of apples, oranges and bananas?
Solfocus uses flat fresnel lenses that works like a magnifying glass, so why not show a photo and talk about photo voltaics enhanced by fresnels instead of confusing the topic by showing the big commercial power reflector systems (really a completely different catagory of product than flat modular panel systems).
And Nanosolar doesn't use concentrators at all! This is a thin film company that uses nanotechnology in its layers. This is actually the opposite of concentrators, because it uses larger areas of cheaper but less efficient photovoltaic material. Whole rooftops would be covered in this material which is created in a process similar to printing.
Come on Treehugger, sharpen up this coverage; this is just unacceptably sloppy. It misleads people into thinking fresnel lens are those big reflectors, while missing the point why Solfocus is using fresnels in the first place. And Nanosolar shouldn't even be in this article! At least take the time to visit the webpages of the companies you are talking about, then write a focused, acccurate article, then use an appropriate photo to the subject matter.
Completely agree with Dave. This is extremely poor reporting. Where are the editors??!!
Check out Energy Innovation's Sunflower solar concentrator. I work in their building and the relatively small modules practically cover our rooftop - and generate significant power. EI is focusing on commercial applications first - and would like to cover every flat industrial roof with their Sunflower product. Soon, hopefully, they will get into residential applications. Their sun tracking technology is truly breakthrough - and uses just two motors to move the entire grid of mirrors over the two axes - keeping costs so low that as manufacturing quantities grow, the payback period should be less than 5 years (if it isn't already!)
Thanks for taking another shot at writing this article, but geez, it's still pretty rough, still apples and oranges being mixed here in a confusing mish-mash.
Can an editor help out here?
Unfortunately, that description of the stirling heat cycle engine is way convoluted...
Please see this wikipedia page for a better explanation of this amazing (and old) technology.
http://en.wikipedia.org/wiki/Stirling_engine
Oh, and that comment about "drawing" electricity from photovoltaics? Language like that makes scientists cry.
I just read the wikipedia page on the topic...
Oh God! It was invented in 1816....
And I found a great link about how it works with animated diagrams.
What is the cost of 0.1, 0.2, 0.5, 1 and 2MW concentrator systems. This technology is definitely good for rural electrification of Africa and I am right away writing project proposals. But I cannot source for finances without knowing the cost.
I'm concerned about another issue that was reported in the July article on the Sunflower solar product...it's being made in China! I understand that labor may be cheaper there but aren't we going in the wrong direction by sending more business outside the U.S. - impact on environment, economics and social issues have a huge cost. I'll be looking for U.S. made solar-products, thank you anyways.
I am a project developer in sub-Saharan Africa, working on poverty alleviation projects. I have a particular interest in solar power-in fact, given our large amount of solar radiation, I believe that we should have concentrator solar projects all over our region. Like Tom Oluka, who wrote to you about costs, I cannot find reliable information on the approximate costs of concentrator projects, per kW or Mw-can someone please help with some reliable data?
Thank you
Just a thought! Because of the location of the motor, the tracking of the sun by the panel, the general heat generated by the setup and the overall location -open fields- would it be possible to attach a blade to the sterling motor, so as to tap into the wind movement in the area also. Let's get it all.