Concentrating Solar to Reach 18 Gigawatts by 2020

According to the Prometheus and Greentech Media report, standard "flat-plate" photovoltaics will have the largest market in 2020, making up 170 gigawatts of installed capacity, and photovoltaic systems that track the sun will have the next largest, making up 100 gigawatts of installed capacity.

These solar-electric technologies will dominate the market for small and medium installations, according to the report, which projects that costs for these technologies will drop below those for solar-thermal "in the medium to long-term."

Costs will vary widely depending on location, but in an analysis of two locations, Tucson, Ariz., and Seattle, the report projected that flat-plate photovoltaics would be cheaper than solar-thermal and concentrating PV.

But the market for large installations, defined as 10 megawatts and larger, is still up for grabs, according to the report.

Solar-thermal advocates say the technology that uses the sun’s heat, instead of its light, to make electricity already is cheaper than photovoltaics today and could reduce costs further at larger scales. Because heat is stored more easily than electricity, solar-thermal plants also could make it easier to deliver power when it’s needed, regardless of when the sun is out.

The report predicts that solar-thermal will account for nearly 60 percent of all utility-scale installations, which will make up 7 percent of all solar installations in 2020.

Hurdles Ahead

Still, concentrating solar-thermal faces a number of challenges that it would have to meet to take market share from PV, said Travis Bradford, president of the Prometheus Institute and an author of the report.

For one thing, both solar-thermal and concentrating PV technologies only can use very direct sunlight, amounting to 60 to 80 percent of the light that standard solar panels can use, according to the report.

While those technologies offset that disadvantage with higher conversion efficiencies, meaning they can make more electricity with the sunlight they get, the fact that they need such direct light limits the locations where they can be cost-effective. In other words, solar-thermal and concentrating PV make more sense in latitudes with plenty of direct sunlight, while standard PV might deliver more electricity in latitudes with less direct light.

Wilder agreed that concentrating solar technologies are more site-specific, but disagreed that standard PV will necessarily be cheaper that solar-thermal in the long run, especially in large installations.

"That’s some Herculean hoping [to expect] that crystalline PV becomes cheaper long-term because, short-term, there’s no question that concentrating [solar-thermal] is cheaper," he said.

(According to the report, PV already is cheaper than solar-thermal in some locations today, such as in cloudy Seattle, while it’s more expensive in others, such as in sunny Tucson.)

Although PV costs have the potential to drop more steeply than concentrating solar-thermal costs, Wilder said he’s not sure that PV ever will be less expensive, per watt, than solar-thermal.

"Concentrating starts out fairly cheap compared to PV and can see some modest reduction in cost, while PV starts out significantly more expensive, but the hope for reductions are significant," he said. "I think PV will get down to grid parity for retail power. But what they’re talking about now is grid parity at the wholesale level, and I’m not convinced that crystalline or thin-film PV will for sure get to that kind of cost point."