Micro Solar Energy From 'Glitter PV'

Sandia National Laboratories scientists have developed tiny, glitter-sized photovoltaic cells that could revolutionize the way solar energy is collected and used.
News release from Sandia National Laboratories
Add to My MSN

 Crystalline-silicon micro-photovoltaic cells measure from 14 to 20 micrometers thick and 0.25 to 1 millimeter across, offering a diverse array of potential uses. 
Photo by Murat Okandan

Content Tools

The following news release was provided Dec. 21, 2009, by Sandia National Laboratories. 

Scientists at Sandia National Laboratories’ tiny solar PV cells could turn a person into a walking solar battery charger if the cells were fastened to flexible substrates molded around unusual shapes, such as clothing.

The solar particles, fabricated of crystalline silicon, hold the potential for a variety of new applications. They are expected eventually to be less expensive and have greater efficiencies than current photovoltaic collectors that are pieced together with 6-inch- square solar wafers.

The cells are fabricated using micro-electronic and micro-electromechanical systems (MEMS) techniques common to today’s electronic foundries. Sandia lead investigator Greg Nielson said the research team has identified more than 20 benefits of scale for its micro-photovoltaic cells. These include new applications, improved performance, potential for reduced costs and higher efficiencies.

Glitter PV Functionality

“Eventually units could be mass-produced and wrapped around unusual shapes for building-integrated solar, tents and maybe even clothing,” he said. This would make it possible for hunters, hikers or military personnel in the field to recharge batteries for phones, cameras and other electronic devices as they walk or rest. Even better, such micro-engineered panels could have circuits imprinted that would help perform other functions customarily left to large-scale construction with its attendant need for field construction design and permits.

Sandia field engineer Vipin Gupta said, “Photovoltaic modules made from these micro-sized cells for the rooftops of homes and warehouses could have intelligent controls, inverters and even storage built in at the chip level. Such an integrated module could greatly simplify the cumbersome design, bid, permit and grid integration process that our solar technical assistance teams see in the field all the time.”

For large-scale power generation, said Sandia researcher Murat Okandan, “One of the biggest scale benefits is a significant reduction in manufacturing and installation costs compared with current PV techniques.” Part of the potential cost reduction comes about because microcells require relatively little material to form well-controlled and highly efficient devices. From 14 to 20 micrometers thick (a human hair is approximately 70 micrometers thick), they are 10 times thinner than conventional 6-by-6-inch brick-sized cells, yet perform at about the same efficiency.

Micro Solar Power Saves 

“So they use 100 times less silicon to generate the same amount of electricity,” said Okandan. “Since they are much smaller and have fewer mechanical deformations for a given environment than the conventional cells, they may also be more reliable over the long term.”

Another manufacturing convenience is that the cells, because they are only hundreds of micrometers in diameter, can be fabricated from commercial wafers of any size, including today’s 300-millimeter (12-inch) diameter wafers and future 450-millimeter (18-inch) wafers. Further, if one cell proves defective in manufacture, the rest still can be harvested, while if a brick-sized unit goes bad, the entire wafer may be unusable. Also, brick-sized units fabricated larger than the conventional 6-by-6-inch cross section to take advantage of larger wafer size would require thicker power lines to harvest the increased power, creating more cost and possibly shading the wafer. That problem does not exist with the small-cell approach and its individualized wiring.

Other unique features are available because the cells are so small. “The shade tolerance of our units to overhead obstructions is better than conventional PV panels,” said Nielson, “because portions of our units not in shade will keep sending out electricity where a partially shaded conventional panel may turn off entirely.” Because flexible substrates can be easily fabricated, high-efficiency PV for ubiquitous solar power becomes more feasible, said Okandan.

Glitter PV Commercial Applications

A commercial move to micro-scale PV cells would be a dramatic change from conventional silicon PV modules composed of arrays of 6-by-6-inch wafers. However, by bringing in techniques normally used in MEMS, electronics and the light-emitting diode (LED) industries, the change to small cells should be relatively straightforward, Gupta said. Each cell is formed on silicon wafers, etched and then released inexpensively in hexagonal shapes, with electrical contacts prefabricated on each piece, by borrowing techniques from integrated circuits and MEMS.

Offering a run for their money to conventional large wafers of crystalline silicon, electricity presently can be harvested from the Sandia-created cells with 14.9 percent efficiency. Off-the-shelf commercial modules range from 13 to 20 percent efficient.

A widely used commercial tool called a pick-and-place machine — the current standard for the mass assembly of electronics — can place up to 130,000 pieces of glitter per hour at electrical contact points pre-established on the substrate; the placement takes place at cooler temperatures. The cost is approximately one-tenth of a cent per piece with the number of cells per module determined by the level of optical concentration and the size of the die, likely to be in the 10,000 to 50,000 cell per square meter range. An alternate technology, still at the lab-bench stage, involves self-assembly of the parts at even lower costs.

Solar concentrators — low-cost, prefabricated, optically efficient micro-lens arrays — can be placed directly over each glitter-sized cell to increase the number of photons arriving to be converted via the photovoltaic effect into electrons. The small cell size means that cheaper and more efficient short focal length micro-lens arrays can be fabricated for this purpose.

Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin, for the U.S. Department of Energy’s National Nuclear Security Administration.  

Previous | 1 | 2 | 3 | Next

Post a comment below.


t brandt
1/6/2013 12:00:52 PM
good points Mc--..I've been following the prices of wind/Pv energy for 45 yrs now. It has always cost considerably more to use them than conventional grid electricity. Those alternatives only make economic sense when their application is for a site way, way off grid, when the cost of running new lines over a great distance is prohibitive, or for less remote applications on your property where demand is very low & occasional- as in a water pump, as you mentioned, or shed lites, etc. In figuring the economic costs, it's frequently forgotten that spending calital up front means you lose the investment potential of that capital. That at least doubles the real cost of the system.....The whole concept of "saving the planet" is based on the false premise that fossil fuels are hurting the environment: That is simply not true. The "GW" concept is fraudulent with exactly zero scientific evidence to back it up. It's only supported by computer models programmed to give the results favoring the supposed need to redistribute wealth & political power.

1/5/2013 4:52:46 AM
I am not as familiar with wind turbines but I see way too much expense and not nearly as much return. The turbines are/have to be HUGE, are expensive and noisy. They are also less dependable than even solar. Several of the big wind farms have already shut down because of the problems...also they seem to catch on fire easily??? I would absolutely do lots more reading before I put money into wind. They do make a good small turbine for keeping water circulating as in a pond or to run a water pump. Just wouldn't want to have to rely on it.

Matt Harrell
1/4/2013 6:26:02 PM
I agree with you there. I would much rather have self-sufficiency via solar and wind for the cost savings than for the "big picture." Considering that with only a 1300 sq ft home I currently spend $1600/year for electricity, I could pay off a net-zero system in short order. I just need the up front cost to go down a bit more.

1/4/2013 4:44:23 PM
If the government would stay out of picking and choosing in this industry things would be a lot better these days. I like this new technology...just get the government to stay out of it. In 2008 (we are installers) we were averaging 4 systems a year, not great but growing. Since then with all the pressure and interference we are installing the first system since! This is a technology that was growing slowly but steadily. People were educating themselves and making good choices. You may not believe this but out of the 14 systems we sold...only on couple professed to be doing it "to save the world". The others were all professed to be Conservatives who wanted solar to be more independent and to save money...in my mind this is a smarter and more logical reason. "Saving the world" is icing on the cake. I think solar is a great thing but it needs to be done on a gradual small scale using current construction where possible and new construction that can be sited as needed. To try to do arrays that will run a whole city will not work...IMHO.

Subscribe Today!

Pay Now & Save 67% Off the Cover Price

(* indicates a required item)
Canadian subs: 1 year, (includes postage & GST). Foreign subs: 1 year, . U.S. funds.
Canadian Subscribers - Click Here
Non US and Canadian Subscribers - Click Here