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Printed solar cells the size of a ballpoint pen tip are tiny, but mighty

By | December 15, 2011, 11:07 AM PST

Startup Semprius took the transfer-printing technology it originally developed for flexible electronics and applied it to solar cells. What did they create in return? Tiny solar cells — each a dot the size of a ballpoint pen tip — able to convert 41 percent of solar energy into electricity using low-cost lenses to concentrate the sun more than 1,000 times.

The Energy Department’s National Renewable Energy Lab announced Wednesday it had recently validated the 41 percent efficiency of the company’s solar cells. Semprius was selected by the DOE and NREL as one of its PV Incubator (now called SunShot) companies. The startup, which began at the University of Illinois, has piqued the interest and investment dollars of venture capitalists and power gear giant Siemens. Last June, Siemens took its partnership with Semprius considerably further and bought a 16-percent stake in the company.

How it works

Semprius makes solar concentrating photovoltaics — a clean-energy mashup of solar panels and solar thermal tech — that uses mirrors and lenses to concentrate light from the sun onto super-efficient cells.

Semprius makes the array of gallium arsenide-based micro cells by growing a semiconductor on a substrate and then using a machine to rapidly transfer it to a wafer. Layers are added to create a triple-junction solar cell.  This patented micro-transfer printing process allows thousands of cells to be stamped at once.

The triple-junction cells are tiny and occupy only one-one thousandth of the entire solar module area. Lenses are then used to concentrate light on the tiny solar cells.

Each solar cell’s tiny footprint and the low-cost lenses allow modules to pack more power in a smaller space.  And by using lots of small cells, unwanted waste heat is distributed more easily over the cell’s structure and eliminates the need for expensive thermal management hardware, according to the NREL. The upshot? Semprius execs say it can slash manufacturing costs by 50 percent.

Solar concentrating PV does have its drawbacks. The technology tends to have more parts than traditional PV, which can add to the cost of building and maintaining a large-scale project. In other words, there’s room for companies like Semprius to use innovation to reduce costs of CPV.

A few CPV solar companies have had success. For example, California-based Amonix is supplying a concentrating PV system for a 30-megawatt solar farm near Alamosa. Its system, which is manufactured in the U.S., powers a 5-megawatt powe plant owned by NextEra Energy in New Mexico. The company also received $4.5 million from the DOE to develop a new dual axis tracking system as part of the agency’s SunShot program, which aims to cut solar costs to $1 per watt.

Photo: NREL

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Kirsten Korosec

About Kirsten Korosec

Kirsten Korosec is a contributing editor for SmartPlanet.

Kirsten Korosec

Kirsten Korosec

Contributing Editor

Kirsten Korosec has written for Technology Review, Marketing News, The Hill, BNET and Bloomberg News. She holds a degree from Northwestern University's Medill School of Journalism. She is based in Tucson, Arizona.

Follow her on Twitter.

Kirsten Korosec

Kirsten Korosec

Kirsten does not have financial holdings that would influence how or what she covers.

She writes for SmartPlanet and is not an employee of CBS.

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0 Votes
+ -
peeked?
Seriously, "The startup... has peeked the interest and investment dollars..."?

PEEKED?
Posted by gork platter
15th Dec 2011
+2 Votes
+ -
Yup, seriously
Yes, I suffered an unfortunate typo. I do know the difference, which probably makes it worse somehow. Thanks for pointing it out though. Wanted to add: I've made the correction and it's been changed to piqued. It might take awhile for it to show up.
Posted by kirsten korosec
Updated - 15th Dec 2011
+2 Votes
+ -
Tough Crowd, Albeit a Small One
Unfortunately, the typo is one that a spell checker would not catch... I see that this technology is being applied on a large scale power plant, but will it have applications for home installs as well?
Posted by denverjomo@...
15th Dec 2011
0 Votes
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Scope and the reality!
The solar power rich regions, the deserts, especially the Gulf countries can be the best places of experiments with the Semprius, PV cells to generate Electricity? But unfortunately, these countries do not bother about such power generations and find the easy way of cheaper power by using Gas and Oil (Gas Turbine & Diesel/ HFO based Generators)
Agencies fighting against Global warming and CO2 emission should join with Siemens this method of Power Generation all over the world wherever possible!
Posted by p_mani10@...
Updated - 15th Dec 2011
+2 Votes
+ -
Good News in the Sunshine
Israel and several North African and Mid-East countries are developing photovoltaic arrays for general power generation but also for desalinization plants. Even (maybe especially) oil producing countries in the region are recognizing that the petrochemical energy generation decades are coming to an end. The raw material, as supply declines, becomes too rare to burn.
Posted by DCGadfly
16th Dec 2011
+1 Vote
+ -
Government Regulation of Energy
Since this is a power-generating means, I presume that it won't be subject to the same rigor the FDA requires of consumed goods. But as these things degenerate with time, won't toxins be released into the ari and water supply? There needs to be a Solar Regulator Commission or NRC should take on the responsibility of determining environmental impact.
Posted by QASIMARA
15th Dec 2011
0 Votes
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Tiny Printed Solar Cells
I hope they can eventually make units small enough to set out on my condo porch, that can power everything in my home. The units available now are so large and can only run one appliance and a couple of lights, from what I've read about them, and are so expensive that the average person can't afford them.
Where can the average person buy stock in the company???
Posted by isciencenat1
16th Dec 2011
+1 Vote
+ -
there are a couple of issues with your idea
one, concentrating solar requires tracking the sun, so it's more complicated, needs a motorized mount.
two, though these are showing a great improvement in efficiency, maybe 3 times that of the common panel, powering a whole house or condo is still going to take a number of square meters of sunlight. Setting something on your porch isn't going to do it, ever.
Posted by kevinrs1
18th Dec 2011
+1 Vote
+ -
Tiny solar cells
I just read in news week that a form of cheaper more efficient silcon has been invented. This will make solar panel alot more affordable. Hopefully this tiny solar cell will do us some good also. Looks like we have alot to look forward to.
Posted by Annishanabe
17th Dec 2011
+1 Vote
+ -
maybe a space application?
Ideally, this kind of solar power, placed on space based solar power generation, would solve our energy problems completely, even making fossil fuels become abandoned as uneconomical.
Posted by kevinrs1
18th Dec 2011
-1 Votes
+ -
residential applications
Even if the SunShot program achieves their $1/watt goal, such a system would cost a homeowner $20,000 just to capture the power needed to convert fully to solar power. I suspect this figure does not include the necessary power storage element, which would most likely double the total cost.

I wonder if these 'microcells' will retain their 41% efficiency longer than the relatively short (7 year average) productive life span of traditional solar cells? If...IF...someone can manufacture a solar array for residential use that guarantees retention of at least 90% of its originally rated output for 10 years, and costs only $1/watt INCLUDING storage and distribution costs...then we can talk about a sensible purchase for homeowners. Absent meeting these conditions, a solar system is only a feelgood toy, useful only for a rich homeowner's bragging rights.
Posted by decryobliviots
19th Dec 2011
0 Votes
+ -
residential applications - where do you get your numbers?
7 year average? quote some sources please! My Sharp solar panels are warrantied for 25 years and estimated deterioration of efficiency is only about 1% (or less) per year. I have had them for 4 years and have not seen ANY deterioration of output yet so I suspect your 7 year average is grossly inaccurate. And you say "necessary power storage element"... hardly relevant at all. Most homeowner mounted arrays do NOT include batteries. These are more common for those who like "off the grid" or remotely. Most people with solar panels on their roof are grid tied. So basically, it sounds like you making stuff up and don't really know what you are talking about.

http://en.wikipedia.org/wiki/Photovoltaic_system (general info, including the commonly grid tied systems)

http://info.cat.org.uk/questions/pv/life-expectancy-solar-PV-panels (general info about lifespan of panels).
Posted by tinhart
26th Jun
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