Green Tech

SolFocus, a maker of concentrator photovoltaic systems, has signed a $103 million (80 euro) deal with Empe Solar, a Spanish group that promotes solar energy use.

SolFocus panels, made of mostly aluminum and glass, are 95 percent recyclable.

(Credit: SolFocus)

Concentrator photovoltaic (CPV) systems typically use lenses and mirrors to concentrate light on solar cells to maximize the amount of electricity they can generate.

SolFocus plans to install over 10 megawatts of CPV systems across southern Spain for Empe Solar between now and 2010 as part of the deal.

SolFocus has already completed three utility-scale projects in Spain.

The 10-megawatt installation would collectively generate enough energy to supply a town of 40,000 residents, and eliminate 27,000 tons of CO2 emissions per year if used to replace traditional fossil fuel energy generators.

It's the largest deployment of concentrator photovoltaic solar energy systems in Europe so far, according to a joint statement from SolFocus and Empe Solar.

Sunny Spain is to be the recipient of $103 million worth of CPV systems between now and 2010.

(Credit: SolFocus)

"Empe Solar seeks only the most innovative solutions to reduce electricity production costs for our customers. SolFocus has proven its technology's value in our region, and we are confident it will enable us to quickly achieve our cost targets for carbon-free energy," Empe Solar partners Eduardo Goicoechea and Sebastian Sagues said in a joint statement.

The other claim to fame SolFocus makes is that its CPV systems themselves, which primarily consist of aluminum and glass components, are kind to the environment since they are 95 percent recyclable.

But SolFocus is not the only company touting good news Monday for solar technology. Cool Earth Solar announced earlier it's rolling out its solar balloon prototypes over the next two weeks.

There are two approaches to magnifying sunlight to make electricity--either concentrating light to make heat or concentrating light to boost solar cells' production.

Cyrium Technologies on Wednesday said that it has raised $15 million to compete with incumbent concentrating photovoltaic cell manufacturers. The series B round was led by the Quercus Trust.

Click on the image to see a photo gallery of concentrating photovoltaic technologies.

(Credit: SolFocus)

The company is one of a handful of firms that makes high-end, efficient solar cells. These high-efficiency cells are used in conjunction with mirrors or lenses to boost output of solar arrays.

Commercial versions of these multijunction cells--essentially three cells stacked on top of each other--have an efficiency of about 37 percent, far higher than silicon cells, which are in the 15 to 20 percent range. But they are substantially more expensive and only used for specialized applications like concentrating photovoltaics or for satellites.

The two leading companies in this area are Emcore Solar Photovoltaics and Boeing company Spectrolab. These companies sell to concentrating photovoltaics firms that design solar arrays around the cells.

At an industry conference earlier this year, Cyrium Technologies President and CEO Stephen Eglash said the company intends to compete with Emcore and Spectrolab by delivering more cost-effective and efficient cells.

The company intends to modify the individual cells by applying quantum dots, a nanotechnology approach which will increase output, he said. Although he didn't specify when products would be available, Eglash said that its first-generation cells will have efficiency of 41 percent, and the second generation will have 45 percent efficiency--higher than most cells created by researchers.

IBM has developed technology that will let solar cells withstand the heat of more than a 1,000 suns.

At a technical conference on Thursday, representatives from IBM Research's photovoltaics research will present a method for cooling concentrating photovoltaics, a solar design where light is magnified onto high-performance solar cells.

A SolFocus 6.2-kilowatt CPV device being tested in Spain. Click on the image to see a photo gallery of other concentrating photovoltaic systems.

(Credit: SolFocus)

Heat is a serious issue when it comes to concentrating photovoltaics, or CPV. The efficiency of cells degrades at high heat and can damage, and conceivably destroy, equipment at extremely high temperatures.

IBM said that its liquid-metal cooling technique, adapted from high-powered computers' chips, can remove roughly three-quarters of the heat generated by a CPV system.

CPV arrays use lenses and mirrors to magnify light onto solar cells that convert light to electricity. By cramming more light onto cells, the panels can generate more electricity.

The technology, which has been around for decades, is being pursued once again by a number of companies, most of which are designing systems for solar power plants.

These plants have rows of CPV systems that track the sun during the day and magnify light hundreds of times.

As part of IBM's Big Green Innovations initiative, researchers looked into applying the company's chip design and manufacturing expertise in solar. It found that CPV companies had not paid enough attention to thermal problems, particularly as they move to higher light concentrations.

"It's clear that everybody wants to go to higher concentrations," said Supratik Guha, lead scientist for photovoltaics at IBM Research. "In the last few years, CPV has sort of been trying to make a comeback and if you look at the numbers, it does have the potential to be really cheap."

IBM looking at CIGS
Because heat dissipation is important for its high-end processors, IBM has developed a cooling system where a thin layer of liquid metals circulates behind a chip to transfer the heat from the chip to a "cooling block."

IBM has built a prototype of a solar concentrator that uses the cooling technology from its high-end chips.

(Credit: IBM)

IBM has built a prototype of the thermal interface layer on a CPV system. In tests, it found that the technique can dramatically lower the heat of high-concentration devices.

The technique only makes sense for very high levels of concentration, which are used on expensive, high-efficiency triple-junction solar cells, said Guha.

IBM doesn't intend to manufacture CPV devices itself but it does hope to license its thermal interface layer to solar manufacturers, he said.

In addition to working on thermal issues, IBM Research is working on "solution process" techniques for manufacturing CIGS cells. The solution process would be an alternative to the slower evaporation process for making CIGS cells.

IBM is also working on manufacturing silicon solar cells on glass. More fundamental research focuses on improving solar cell efficiency through nanowires and nanoparticles, explained Guha.

SolFocus on Tuesday said that it has begun installation of its concentrated photovoltaic arrays at a 3-megawatt solar power plant in southern Spain.

The first 200 kilowatts of solar power to go live will be part of 500 kilowatts that SolFocus will provide in a project sponsored by Spain's Institute of Concentration Photovoltaic Systems, or ISFOC by its Spanish acronym.

SolFocus, which we first covered when it was spun out of Xerox Palo Alto Research Center in 2006, is one several companies pursuing concentrated solar photovoltaics, where mirrors or lenses focus light onto solar cells to produce more electricity. Tracking systems that mount the solar arrays follow the sun during the day to maximize light input.

A 6.2 kilowatt array, part of a solar power plant project in Spain.

(Credit: SolFocus)

The technology competes with solar thermal where parabolic troughs or dishes are also used to concentrate light. But instead of producing electricity from solar cells, the heat from the sun is used to produce steam which turns an electrical generator. (Click here for an FAQ and photo gallery on concentrated photovoltaics, or CPV.)

Utilities are betting on these approaches, along with solar farms equipped with hundreds or thousands of light-tracking traditional solar panels, to make solar power plants.

The Southwest region of the U.S. and Spain have emerged as two of the most desirable places to install these plants.

But different solar technologies are better suited for different environments.

Because they align with the sun very closely, a concentrating photovoltaic power plant will not perform as well on cloudy days, whereas a power field with hundreds of traditional flat-plate solar panels could still generate a significant amount of electricity. The 10-megawatt solar park in Bavaria, Germany, uses flat panels with tracking devices.

SolFocus' design concentrates the light hundreds of times, while companies targeting smaller solar energy systems for corporate buildings have only 3 or 5 times concentration.

The solar power plants are small compared with a typical coal-fired or natural gas-driven plant, which can be hundreds of megawatts. But utilities are investing in solar power plants to meet renewable energy mandates or for peak power needs.

SolFocus has now raised a total of $63.6 million in series B funding to move into production of its solar power plants.

An extra $11.6 million in funding, announced Tuesday, complements the $52 million in series B funding the company announced in September. Altogether, the company has raised $95 million in venture capital.

SolFocus, which was spun out of Palo Alto Research Center (PARC) is perhaps the most high-profile company to pursue solar concentrators, where mirrors and lenses magnify light in order to squeeze more electricity from very efficient solar cells.

These solar installations--usually ground-mounted machines, are typically geared at utilities or large businesses. Concentrating solar power competes with solar farms of photovoltaic panels and solar thermal technology, which uses reflective troughs or mirrors to heat liquid that turns a turbine.

SolFocus also makes tracking systems that maximize the angle of solar concentrators and solar thermal systems.

As the company completes its funding, there are growing concerns over the valuation of public solar companies and whether a recent wave of solar start-ups can provide the products that utilities demand. Venture capitalists are poised to invest $1 billion in solar-related companies this year.

Pacific Gas & Electric--one of the most aggressive utilities in adopting renewable energy--told the San Francisco Chronicle this week that renewable energy companies "technically aren't able to deliver." Because many of the companies pursuing renewable energy technologies are start-ups and not fully tested, PG&E may not be able to meet its goal of using 20 percent renewable energy by 2010, CEO Peter Darbee said.