Based on the above opening lines from one of his most famous sonnets, the 17th century metaphysical poet John Donne wasn’t a fan of Le Soleil. Maybe he just wasn’t a morning person, but I suspect the scientists who’ve been working on photovoltaics for decades, struggling to raise conversion efficiency rates a few points at a time in hopes of some day, in the distant future, making it a commercially viable energy source, might share Donne’s frustration. After all, the sun has, to date, proven to be fairly intractable when it comes to harnessing its rays to power our energy-hogging homes.
With all due respect to Donne, it might be time to change our tune. After decades of incremental advances, solar power may have reached that crucial “tipping point” whereby it will suddenly begin to grow and advance at an accelerated rate. That’s the considered opinion of Lawrence Kazmerski, a physicist (and longstanding AVS member, so he was well known to his audience) with the National Center for Photovoltaics at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. “Solar is real, not just in the future, but now,” he insisted.
Kazmerski cuts a colorful figure, and has a strong whimsical streak when it comes to making creative Power Point presentations. He was the perfect person to kick off an 8 AM session on Tuesday, when most of us were still groggy, waiting for the caffeine to kick in. The guy created his very own movie “preview” — complete with theme music — of his talk, in hopes of emulating Al Gore and winning an Oscar one day. Okay, not really, but it a little levity goes a long way to enliven a presentation.
And his whimsy frequently makes a point: He showed a European pro-solar power commercial done in the style of a horror movie, in which innocent London civilians were caught in a downpour of increasingly larger batteries raining down from the sky. The tagline: “970 trillion kw of energy fall from the sky every day. Good we can’t see it. Bad we don’t use it.” The world currently needs 14 TW of total primary energy, and we’ll need an additional 10-15 TW by 2050. Solar cells could be a strong contender to help close that future energy gap — if we can just accelerate the rate of scientific advancement and commercial development even more between now and 2050.
Since its birth in 1953 at Bell Labs, the solar cell has had varying fortunes. It started out strong: one year after Gerald Pearson, Daryl Chapin and Calvin Fuller created a working solar cell in the lab, it had found its way into the “real world.” (For an April 24, 1954 demonstration of the concept, Bell Labs built an erector set ferris wheel powered by solar cells. The press ate it up.) That rapid development curve was due in part to the Sputnik era: solar cells were ideal for powering satellites orbiting in space. The first solar satellite, Vanguard, was launched on March 17, 1958, and it worked for 2-1/2 years. It’s still “the oldest remaining space debris up there,” according to Kazmerski. But on earth, the technology floundered, being neither efficient enough, or sufficiently cost-competitive, for widespread energy generation.
Those early solar cells weren’t especially powerful, but they were incredibly robust. Kazmerski showed an old solar radio from 1957 — it still works! So, reliable, yes. Efficient? Um… they’re working on it. Based on what I’ve heard from numerous speakers at the IPF forum, there’s been an impressive increase in solar efficiencies, and in cost competitiveness.
According to Kazmerski, prices drop 20% with every doubling of capacity — not exactly Moore’s Law, but none too shabby, either.) There are commercial solar cells in production today with efficiencies above 20%, thanks to companies like BP, Saturn, and Sun Power, among others. Photovoltaics is becoming big business. In fact, while companies used to settle for silicon scraps from the semiconductor industry to build their devices, in the last couple of years, demand for silicon in the PV sector actually outstripped the semiconductor industry — PVs now consume half of the silicon in the world. There was even a silicon production capacity shortage as a result of the staggering increase in demand.
The R&D focus is now shifting to alternative technologies, such as thin films, solar cell concentrators, and organics (especially plastics), with quantum dots, thermophotonics, and bioinspired technologies further off in the future. “There’s a lot more out there besides silicon,” said Kazmerski. Richard King of Spectralab reported on their work using multijunction concentrator solar cells to overcome some of the fundamental efficiency limits. He and his colleagues succeeded in building the first solar cell to reach over 40% efficiency — a feat Kazmerski described as “equivalent to breaking the four-minute mile” — with the highest solar conversion efficiency for type of solar cell to date. That’s in the lab, of course, but it bodes well for the future.
So Kazmerski has high hopes for solar based on the latest advancements. He’s further encouraged by growing government support for the technology, although more R&D investment is needed. Japan founded a subsidy program for photovoltaics in the 1990s, and Germany’s Feed-In Tariff Program has made that country the largest PV market in the world today. The US, alas, has the lowest PV market share, being more concerned of late with finding “weapons of mass destruction rather than methods of mass production,” quipped Kazmerski.
But the Bush administration has finally acknowledged the importance of PV technology, and is now providing some $20 billion/year in funding for programs like DOE’s Solar America Initiative. Kazmerski predicts that by 2030, there will be a 500-fold growth in US installed solar capacity.
Of course, as Union College physics professor (and fellow blogger) Chad Orzel points out over at Uncertain Principles, efficiency isn’t the only issue. He reports on a recent colloquium by Peter Persans of Rensselaer Polytechnic Institute, who works on solar cells in his research — specifically, a promising new type using amorphous silicon and “quantum dots.” Here’s Chad’s paraphrase of Persans’ comments on commercial viability:
“In order to meet the energy needs of the US entirely with solar power, we would need to cover 0.2% of the land area of the US with photovoltaic cells, roughly equal to the area of paved roads in the US. And that’s using solar cells with an efficiency of 50%, not too far below the theoretical maximum for a single-layer device….
“[I]n order to build that sort of solar energy infrastructure, we would need to produce and install 2,000 square kilometers of solar cells a year for 20 years. … We currently produce about 200 square kilometers of plastic film a year… [S]o we’re talking about producing complicated solar cells at ten times the rate that we make plastic wrap. That’s what they call a ‘significant technical challenge.’”
Perhaps the most significant “tipping point” for solar has been in public perception. I distinctly recall attending a science fair 20 years ago where a high schooler proudly demonstrated how he could cook a hot dog using solar power. It literally took several hours to accomplish, and even then, the snippets of “dawg” he handed out as samples to passersby were lukewarm and grayish in color — decidedly unappetizing. It colored my perceptions of the potential for solar power for years.
My skeptical views have changed a bit; I now see solar as a viable complementary energy source (I doubt very much it will become our sole energy source). One of the student attendees, Lee, and I were chatting after the talk, and agreed that if we had the money, the land, and the wherewithal, we’d totally install lots of solar panels in our respective custom-designed “dream homes” so we could go completely “off the grid.” (Lee’s keen on a mud floor, too. Apparently it’s all the rage with environmentally conscious young people these days, plus “it looks really cool!”)
One has to take weather variations into account, of course. The solar solution is perfect for southern California, but might be a problem in less sunny environs. So I was pleased to hear that there’s a middle ground, wherein one can install solar paneling as a primary energy source during the summer, funneling any extra energy to the power station in return for “credits.” And those credits could be redeemed during the colder periods. Strikes me as a “win-win” compromise.
Besides, solar panels are kinda pretty, in addition to being practical and environmentally friendly. Call me shallow, but it’s always nice to see good technology in pretty packaging. Architects and builders are far more likely to jump on the solar bandwagon if adding solar panels enhances, rather than detracts, from their “vision.”