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Planet-Profit Report, reporting on sustainable development in the Western United States.

The Southwest and CPV: a perfect solar pair

Little used but cost-effective system gets a major try-out

Colorado will soon be home to the largest installation of concentrating photovoltaic solar – a technology that doesn’t require water to produce power, is highly efficient and uses less land. It’s also a technology that has been ignored by utilities in the U.S. – that is, until now.

Last month Cogentrix Energy, a wholly owned subsidiary of Goldman Sachs Group, announced it had entered into a contract with utility Xcel Energy to design and develop a 30-megawatt concentrating photovoltaic solar farm near Alamosa, Colo. Xcel signed a 20-year contract to buy power from the solar farm, which will generate electricity for about 6,500 homes. Amonix, a California-based company that has spent 20 years honing the technology, will supply the concentrating photovoltaic – or CPV – system. The total project cost is estimated between $135 million and $150 million and construction is expected to begin early next year, Jef Freeman, vice president of development at Cogentrix and project manager of the Alamosa site, told me recently.

CPV technology is far from main stream and its exit from niche status hinges, in large part, on the success of the Alamosa project. It also could bode well economically for the southwest, a region with a uniquely high percentage of direct sunlight – the key, and oftentimes the crux, to CPV.

“This is technology that hasn’t been implemented on a broader commercial scale, which coupled with pretty tight credit markets” have made it more difficult to get financing, Freeman said. Cogentrix has applied and is hopeful that it will receive a federal loan guarantee to help fund the project.

“This is really a poster project for what loan guarantees are trying to achieve,” Freeman said. “It’s our hope that this project will make the next application – whether we’re doing it or someone else is – easier” to receive financing.

So what is CPV?

In the simplest of terms, Amonix’s technology takes the equivalent of a magnifying glass called a Fresnel lens, and concentrates the sunlight 500 times onto a semiconductor that is smaller than the size of a penny. That semiconductor converts the light into electricity, explains Amonix CEO Brian Robertson.

CPV is unlike the two other common technologies: photovoltaic solar (PV) and concentrating solar thermal (CST). With conventional PV, sunlight hits a solar panel that contains silicon-based cells and turns it into electricity. The light isn’t concentrated, which means it’s distributed over the entirety of the panel. These panels are less efficient as a result so many more are required; Hence, the larger footprint than CPV.

With concentrating solar thermal, sunlight is concentrated onto a fluid. The fluid gets hot and generates steam, which in turn, runs a steam turbine the same as a natural gas generator.

“What’s happened is that costs have come down so much that concentrated solar thermal is wildly out of the money now,” said Robertson. “There’s no economic justification to do concentrating solar thermal when it’s more expensive. And it uses enormous amounts water; depending on the technology it can use something around 1,000 times as much water.”

The idea behind CPV, explains Robertson, is to use a much less expensive substance – the lens – to collect light and focus it on less of the more costly material – the semiconductor.

Cost breakdown

Amonix’s CPV technology also is unique because it uses germanium, not silicon cells. Solar cells made out of silicon are, as Robertson explains, essentially the Honda Accord of the industry. Meaning they’re easy to come by and relatively cheap. But about 10 years ago, the U.S. Defense Department funded research to find something more efficient than silicon for the solar panels it uses to power satellites. They found germanium was not only more efficient, but could withstand the extreme temperature swings that occur in space.

Amonix was the first company to use germanium cells here on earth. Out in the field, the cells are 40 percent efficient compared to silicon cells, which have 24 percent efficiency in the lab, Robertson said.

“Germanium cells are more expensive, but we use so little of it because we’re concentrating it, so it effectively halves our costs,” Robertson said.

Southwest and CPV: A Perfect Pair

Still, there are pros and cons to CPV.

“If you have an area with a lot of direct sunlight for a high percentage of hours in the year this is a great strategy because the performance is phenomenal and the whole cost structure is very attractive,” said Robertson. “If you’re in an area, like say Florida, that’s bright, but also very cloudy, this is not the right strategy.”

Enter the Southwest. The area west of the Texas-New Mexico and then north up to Denver has the highest percentage of hours of direct sunlight than anywhere else in the U.S. It’s here, where CPV is efficient enough to directly compete with natural gas-fired power generation.

“The utilities have definitely gotten smart, especially in the Southwest,” Robertson said. “They know what the costs are; they know where the performance is. In some cases, they’ve been driven by legislation to adopt renewable energy, in other cases not, but they’re all kind of jumping in.”

As a result, politicians and regulators have become intensely interested in creating industrial clusters, essentially attracting companies involved in every aspect of the solar value chain into a certain geographic area. The idea is create what Silicon Valley is for computers and software, but in the Southwest with solar.

University of Las Vegas-Nevada has created a solar solution center for research and development, for example. “Nevada is trying to attract everybody from steelmakers to semiconductor companies to people like Amonix to create a cluster of excellence all around solar,” said Robertson. “Arizona is trying to do the same thing.”