When I got into solar energy research in 1981, I wanted to change the world. I worried to my father that I’d never see widespread use of solar energy in my lifetime. That made him worry, too—about my future job prospects. As it turned out, there were plenty of jobs and I got to play my part in the history of human technology. I was one of a dedicated legion of scientists, engineers, technicians, laboratories and companies who eventually made photovoltaic cells into a commodity product: durable panels that achieve a miraculous-seeming conversion of sunlight to electricity, without needing any moving parts.
Years of inspiration in one simple image.
For inspiration, an artsy poster has hung near my desk at home since my first solar R&D job. A spectacular desert arch, abstracted in blocks of tan and brown, is backlit by an enormous yellow sun; the caption claims the “Largest Solar Power System in the World” for Natural Bridges National Monument in Utah. My wife, Carol, wishes I’d take that old poster down already, but I enjoy the reminder of my stint in the MIT Lincoln Lab group that had designed the Utah photovoltaic (PV) system. A third of a century after PV was invented at Bell Labs in 1954, our group was improving the electronics needed to build safe and efficient systems from PV modules.
The “world’s largest” 1980 PV system delivered about 100 kilowatts (kW) of power at high noon in the desert sun. Today, you can walk almost any block in Palo Alto, California, and see 100 kW of PV panels spread among a dozen home roofs. And if you want to see the World’s Largest Solar System in 2016, travel to Asia where you can find a couple of systems more than 800 megawatts (MW = 1000 kW) in size. There are now over 100 PV systems that are each over a thousand times bigger than that pioneering Utah system.
I’ve witnessed a technology revolution during my career in solar energy R&D as the industry has outgrown its niche remote-power market and become a $100 billion per year powerhouse. In today’s dollars, the cost of modules has fallen from about $34 per watt of generating capacity in 1980 to below $0.57/W today, and the price of PV will fall sharply again next year. The world now has 277,000 MW of photovoltaic installed, generating 1.4% of our energy. Two-thirds of new U.S. energy generating capacity in 2015 was wind and solar generators, boosted by a similar revolution in wind technology.
The 100 kW system at Natural Bridges. Photo: NPS/Tom Gray
Obviously, there’s a long way still to go, but I feel privileged to have had a front row seat for this revolution in solar energy. What lessons have I learned?
- The “experience curve” drives the cost of modular products like PV down by nearly 20% every time the scale of the industry doubles. This leads to amazing growth when new technologies satisfy market demand.
- Existing energy technologies are deployed on such massive scale, and with such big tax breaks that these fossil incumbents are hard to unseat. New energy technology R&D must show clear performance wins, product reliability, production yields and bankability before private investment capital flows in.
- Successful lab-scale R&D doesn’t stand alone. R&D attracts more funding as low costs and big markets are demonstrated, and it must be informed by the problems faced during scale-up. In the case of PV, the driving force came from wafer-based crystal silicon PV and that technology is still the mainstay of the industry.
- Let a thousand flowers bloom! Transformational technologies like silicon PV leave the wreckage of many promising technologies and companies in their wake. Most competitors to silicon PV were dead-ends, but some contributed a manufacturing technique, material or design feature used in today’s cells. These challengers also kept the pressure on crystal silicon PV to continuously reduce costs and raise efficiencies.
- Consistent government support for deployment is critical to launch new renewable energy technologies. For PV, critical subsidies came from Japan’s “70,000 Solar Roof initiative” (1994), Germany’s “Feed-In-Tariff” (1999) and China’s aggressive loans and subsidies that enabled their PV companies to scale up PV manufacturing at astonishing rates during the last decade. These and other national subsidies led directly to reduced costs and a critical flow of private capital to the PV sector.
A 458 MW system at Copper Mountain, Nevada. Photo: Nevada Governor’s Office of Energy
Fortunately, we now have inexpensive solar electricity in our toolkit to combat climate change. California has mandated an electricity supply that is 50% renewables by 2030 and it looks like that milestone can be reached economically with today’s technologies. However, going the next step to reach an all-renewable future will be a technical and institutional challenge because of the natural variability of sun and wind and the diverse incentives for utilities and other players.
Happily, we are close to the tipping points in grid flexibility, storage, electric vehicles and demand-side-management technologies that will be needed to relegate fossil fuels to small markets like air travel. Government commitment to support both R&D and deployment will be essential to dramatically reduce fossil fuel emissions and arrest climate change in time to avoid its worst impacts—including turning millions of Earth’s most vulnerable people into climate refugees.
That old PV poster on my wall reminds me daily of what a determined bunch of scientists, engineers and entrepreneurs, backed by government support and private money, can achieve. If we insist, I’m certain it won’t take 35 years to put the next critical technologies in place.