Solar Cells

Published on November 6th, 2014 | by Tina Casey

New “Tinker Toy” Test Could Send Solar Energy Costs Into Free-Fall

November 6th, 2014 by Tina Casey

Solar energy costs are already dropping faster than you can say “solar energy costs are dropping,” and along comes a new development that could accelerate the trend even more. The project, out of Sandia National Laboratories in partnership with the University of Colorado-Boulder, aims at working around the efficiency limitations of dye-sensitized solar cells.

The idea is to combine the dye-based technology with another material that researchers compare to that icon of childhood play, the Tinker Toy. Dye-sensitized solar cells lend themselves to a low cost manufacturing process, so breaking through the efficiency wall lets you have your solar cake and eat it, too.

Use of MOF in a dye sensitized solar cell (courtesy of Sandia National Laboratories).

A Promising Technology For Reducing Solar Energy Costs…

As described by Sandia’s press materials on the new solar energy cost breakthrough, dye-sensitized solar cells have been around since the 1980’s. As the name indicates, the technology involves specialized dyes that enable the solar cell to absorb light more effectively.

This development made a big difference in solar cell R&D, because it enabled researchers to break down the process of generating a current into separate components. Each “module” can be tweaked to maximize efficiency without throwing the whole system out of kilter.

…But There’s Trouble In Paradise

Where the technology runs into trouble is the tendency of the dyes to “clump” onto the semiconductor material, which is where the action takes place in terms of converting solar energy to a usable current.

Typically, the semiconductor in dye sensitized solar cells is titanium dioxide, a commonly used substance (for example, as the key ingredient in white paint). When the dye eventually aggregates on the titanium dioxide surface, it brings down the efficiency of the solar cell.

Sandia To The Rescue!

To get around that problem, Sandia plans to deploy its expertise in the field of metal-organic framework (MOF) materials.

We’ve previously discussed MOF in the context of Pacific Northwest National Laboratory’s research into next-generation batteries. Described by that team as a “unique, powdery nanomaterial,” MOF refers to a crystalline compound of metal clusters linked by organic molecules, which self-assemble into a porous structure.

The Sandia description is similar, with the added observation that because of the highly ordered nature of MOF, researchers find it easy to “envision and assemble” new structures. It’s not quite as easy as putting together Tinker Toys, but that’s the general idea according to Sandia.

Silicon chip coated with MOF film over an oxide layer, with an array of platinum electrodes (photo by Dino Vournas courtesy of Sandia National Laboratories, cropped and enhanced for clarity).

The new project will involve layering MOF over the titanium dioxide, to lock in the placement of the dye. The secret sauce, though, will be an extra layer of dye enabled by MOF, as described by Sandia:

…the unique porosity of MOFs will allow researchers to add a second dye, placed into the pores of the MOF, that will cover additional parts of the solar spectrum that weren’t covered with the initial dye.

Here’s a couple of snippets from Sandia materials scientist Erik Spoerke enthusing about the potentials:

Essentially, we believe MOFs can help to more effectively organize the electronic and nano-structure of the molecules in the solar cell. This can go a long way toward improving the efficiency and stability of these assembled devices…

…With the combination of MOFs, dye-sensitized solar cells and atomic layer deposition, we think we can figure out how to control all of the key cell interfaces and material elements in a way that’s never been done before.

Before we get too carried away, let’s note for the record that however low the cost of manufacturing solar cells may go, a good chunk of the installed cost of solar energy still hinges on a variety of non-cell factors including marketing, administration, design, permitting, and labor costs. By the same token, though, by chipping away at solar cell costs while improving efficiency you can gain a significant impact on overall solar energy costs.

Group Hug For Lower Solar Energy Costs

As you may have gathered from the above quote, so far the Sandia team is dealing with hypotheticals. To pick up the pace of the R&D, the Energy Department has just awarded the lab an extra $1.2 million for the project through the SunShot Initiative. So, group hug all you taxpayers!

Sandia of course is part of the Energy Department’s network of taxpayer-supported national laboratories, operated by a wholly owned subsidiary of our friends over at Lockheed Martin Corp.

Lockheed is better known for its aircraft and Defense Department contracts, so if you’re wondering about the company’s connection to solar energy check out some of its recent clean energy ventures such as waste gas-to-ethanol, next-generation wave energy, and a nifty little compact fusion reactor.

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Tags: lockheed martin, metal organic framework, MOF, sandia national laboratories, solar energy costs

About the Author

Tina Casey Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

JamesWimberley

Sandia just got a grant to try to get their good idea to work. If one such idea in a hundred works in the lab, and one works-in-the-lab process in ten makes it into commercial production, and one commercial product in ten is really successful, the chance of this idea lowering solar costs dramatically (as the headline suggests) will be 1 in 10,000.

High-tech research is ruthlessly Darwinian: most mutations fail. Both research and natural mutations are hugely important in the long run. Research should be backed by government funders and venture capitalists, as the only way of getting the results we vitally need. But let’s be clear-eyed about the failure rates.
- Michael G
  
  I totally agree which is why it is so discouraging to see so little money going to fund sustainability research. After that little kerfuffle about whether FC or EV is the way to go it is really just us mice scavenging for crumbs. Here’s the IEA’s report on how little is spent proportionately to other R&D:
  http://www.iea.org/etp/tracking/figures/rdd_innovation/
  
  Give PV half the money nuclear gets and we’d be carbon free by now.
Michael G

Organic LEDs reached consumers last year. They were first announced.30 years ago. This may be the same thing. We will likely see incremental increases of 1%-2% a year in PV efficiency from one techology or another and in 20 years today’s 20% solar cells will be worth replacing with 40% efficiency.
- JamesWimberley
  
  Martin Green, an Australian who leads one of the world’s leading teams of pv cell researchers at UNSW, has just predicted that efficiency in commercial cells will double(no horizon given) (link).
  - Bob_Wallace
    
    And for those who may not know, doubling panel efficiency means about a 50% cut in balance of system costs. The same amount of racking and labor with twice as efficient panels puts twice as much power on the grid.
Offgridman

So could this result in a film that could be retrofitted onto existing panels to help their efficiency or reverse the degradation of older panels? If so that could mean a whole new market/labor value chain for the solar industry.
Or is this a process that can only be done during the initial manufacturing of cells? Which higher efficiency for the same area is always going to be helpful, but we are getting to the point of a lot of installed capacity that would be very expensive to change out for higher efficiency panels unless the production is multiples of what is there already.
- Offgridman
  
  Which now makes me wonder if at the end of the 20-30 year lifetimes of our current solar farms if panel efficiencies will have increased and costs dropped enough to make it worth retrofitting them with new ones?
  If so that is going to be a lot of panels coming into the market still having 90-95% or better of their original production capability. This could be quite a boon for the residential or even over seas less developed countries. High quality panels that will basically cost just what it costs to ship them.
  - Bob_Wallace
    
    Only if land values are very high. A paid off 20, 30 year old solar farm still cranking out 90+% of original output will be a cash machine.
    - Offgridman
      
      I wasn’t considering property costs because for a solar farm that was already included in the costs of the first 20-30 years of running. So if you have a site and racking (possibly even tracking) with wiring already in place, wouldn’t panel replacement that could double or maybe triple your output make your cash cow all that much fatter?
      Part of what has me wondering about this is the videos from the tracking farm Zach put up a couple days ago. The guy that was showing them around the place really didn’t want to say what the investment costs of that farm were. Which is understandable because you are starting to delve into corporate profit/loss statements that they want to keep to themselves. Then he did come out with the 40-50 million dollar number to rebuild it currently, but the panels they are using must be 5-10 years old already and might be from back when prices peaked due to the silicon shortage. Another article was talking about the addition at the Indianapolis airport which I think is approximately of a similar size (but may not have tracking) being done for 25 million.
      So there are some wide variances in installation costs, but I know that there are a lot of variables including property costs, location, rebates, and expected output just to name a few.
      Perhaps in places like England where they are already concerned about how much land these farms are going to be using will be more viable for panel replacement in thirty years, whereas that one on the trackers in the desert would be left as is?
      I don’t know, I just get to wondering about things and daydreaming of a future for my boys where renewable energy can make the costs for the consumer almost irrelevant other than maintaining the infrastructure.
      - Bob_Wallace
        
        We’re talking 20 years out so everything we predict is highly speculative and based on today’s conditions.
        
        I can guess that 20 year from now mounting might be radically different. We’re moving toward robotic installation and it might be that the optimal rack, even panel design, could greatly change. It might not be an issue of sending in a crew to unbolt the old panels and bolt in new ones. Replacement style panels might no longer be manufactured.
        
        I can imagine, for example, a racking system which used frame-less panels and racks that consisted of long slots into which panels were slid. When in place the connections might be made by contacts built into the slots. (Weather and vermin protected.) All wiring might be built into the rack system at the factory.
        
        If a change something like that happened then swapping out old panels for new would mean pretty much a tear out of the old racking system.
        —
        
        Speaking of robotic installations, someones built a robotic system that pours the rack ballast and installs the brackets for rack attachment in one pass. Just back up the concrete truck and start the process going.
      - Offgridman
        
        Thanks Bob, some innovations that I haven’t heard about before and wasn’t taking into consideration.
        You know to me it is kind of funny because all my life when talking with older people you usually heard about how the world was going to heck and how good things were in the good old days. But now that I am well into the second half of my century of watching the world go by it continues to amaze and impress me. So many changes and improvements over the past fifty years in technology, medicine, renewable energy, just everything help to make the world now and the future to come so rosy. Of course politics is still mainly the same pile of manure that it has always been. But maybe someday we will even figure out a way to keep people that get on power trips from trying to control us.
        Time to go back to wondering, learning, and dreaming.
        Have a great day!
      - Bob_Wallace
        
        I’m also of the ‘older persuasion’ and think I can look back somewhat realistically. The only things I see that were better, the only things we’ve lost, are more space per person and easier job acquisition for the less educated.
        
        When I was a freshman/sophomore we could take a sandwich and the Sunday paper and go spend a sunny afternoon in Cades Cove. Now it’s bumper to bumper. Same with all the other ‘best’ spots such as Yosemite. The same has happened with the remote seashores we used to fish when I was first in graduate school. Where one could spend a weekend and never see another person it’s now wall to wall condos and hotels.
        
        And people with marginal educations could go to one of the several local factories, get a decent paying job and support themselves and their family.
        
        Over the long run we need to reduce the world’s population to half or less of what it now is. And we’re going to have to figure out a better way to dispense goods to those whose labor we don’t need as we continue to replace labor with automation.
        
        But having grown up with smallpox, polio, no AC (in the SE), cars that were trash by the time they acquired 100k miles (and were rolling death traps), poor access to information, difficult long distance travel, etc. I have no desire to return to those old days. Heck, I grew up farming with horses. Give me an air conditioned tractor cab with a good stereo….

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New “Tinker Toy” Test Could Send Solar Energy Costs Into Free-Fall