The solar industry never sleeps. Why would it? The sun produces no carbon emissions, there is an unlimited amount of it, and best of all, it's available to everyone. Figuring out ways to harness the sun's energy affordably, efficiently and sustainably are all goals that continue to drive the solar industry.

This drive is evidenced by the wide array of new solar technologies bursting onto the scene today. It seems every week another new spin on the traditional solar panel seeks to sidestep one or more of the existing limitations, primarily system cost and availability of materials.

Over the years, the cost of solar panels has declined about 5 percent per year. Most of this decline is due to increasing efficiency of cells and increasing economies of scale due to larger and more automated factories.

The cost of solar panels has fallen substantially, around 20 to 30 percent in the last six months; this follows an overall demand that has been growing steadily over the last 10 years (nearly doubling every year). The sluggish economy has driven the recent fall in cost. "This pull-back has been tough on the solar industry," said Shyam Mehta, a senior solar analyst with Greentech Media, a New York City market research firm that focuses on renewables. "But it will also have a weeding-out effect, and once the air clears we'll be left with a stronger industry and lower prices for everyone."

The U.S. has traditionally lagged behind other countries in solar, but now that's changing with the enthusiasm of a new generation and a plan to create more jobs in the solar sector. Germany has been the world leader in solar for some time--47 percent of all solar installations were in Germany in 2007--however, Spain was leading last year before capping the demand because so many people there were taking advantage of the generous incentives.

The Next Hope for Decreasing Costs: Thin-film Photovoltaics

One of the most exciting solar technologies to come along is thin-film photovoltaics, one answer to costlier silicon photovoltaic (PV) wafers currently in use. A thin-film solar cell is made by depositing one or more very thin layers of photovoltaic material onto a substrate via a variety of methods. The thickness can be one or two microns thick (as opposed to 200 to 300 microns thick with regular solar cells). These types of solar cells are usually categorized according to their materials, such as cadmium and telluride (CdTe) or copper, indium, gallium and selenium (CIGS).

"Thin-film can be tricky to make, but it promises a lower cost than wafers as well as good efficiencies," said Mehta. "There has been a lot of venture capital going into thin-film, but the challenge is manufacturing speed," he said. "Many companies are working on thin-film technology, and many have been betting who will break through first."

Achieving a lower-cost solar option (cost per watt) is one of the main goals of thin-film technology as well as offering a sustainable alternative. "Thin-film is not as efficient as traditional solar panels; but because they use 1/600th of the silicon, they are much cheaper," said Britt Weaver, CFO for Sencera, a Charlotte, North Carolina-based developer and manufacturer of thin-film silicon solar modules. He noted that the silicon they use is adhered to glass by chemical vapor deposition that creates plasma fields, which can be manipulated.

Because thin-film requires more panels to make up for the lost efficiency, it is ideal for very large spaces. "For a winery, thin-film would be a cheaper option because there is more land space for the panels--as opposed to just a rooftop, which may be better suited to traditional crystalline panels," said Weaver.

Another type of thin-film solar panels uses quantum-dot technology, which has been used more frequently in medical applications but is gradually making its way into the solar cell market. What makes quantum-dot technology different than traditional silicon wafer-based solar technology is that it utilizes much less energy during production and the manufacturing process is relatively simple.

"The process of making the semiconductor material and applying it to film is based on silkscreen printing, whereas silicon must go through two molten processes, 100 times more energy," said Steven Squires, CEO of manufacturer Solterra Renewable Technologies in Tempe, Arizona. "So the environmental footprint is much less with quantum-dot technology."

Squires said that another advantage of quantum-dot thin-film technology is that it uses metals that are naturally plentiful as opposed to the more commonly used cadmium, indium and gallium metals, whose natural supplies are more limited. These factors combined also allow for a more affordable solar cell. "Most people don't know what quantum dots are right now, but this technology will be big in the next five years," said Squires.

Solterra called quantum dots "mega-molecules" of semiconducting material that are smaller than living cells. Quantum dots interact with light in unique ways to give off different colored light due to their size, shape and the material they are made from. Using the company's proprietary technologies, they can manufacture low-cost solar cells for less than the cost of traditional solar cells.

Other Technologies

Technologies don't end with thin-film. Many companies and institutions--more than 120 North American PV companies exist today--are researching other innovative ways to efficiently harness the sun's power. For example, the Australian National University and Amsterdam's Institute of Atomic and Molecular Physics are developing a technology that utilizes particles of silver to radiate small amounts of light in a way that brings the efficiency of thinner cells much closer to that of thicker cells.

Another company, Cool Earth in Livermore, California, has developed eight-foot balloon-shaped concentrators that, when inflated with air, naturally form a shape that focuses sunlight onto a PV cell placed at a focal point. This equates to needing fewer cells to produce more electricity, with a single cell in one concentrator generating about 300 to 400 times the electricity of a cell without a concentrator.

And still another company, Solaren Corp., has plans for a space-based orbiting solar farm, with the idea that solar panels would have access to nearly constant sunlight, thereby providing electricity around the clock. The idea has sparked interest with PG&E, which wants to buy 200 megawatts of electricity from the farm when it's built.

Having an innovative idea is just the beginning, however, when it comes to marketing new solar technologies. According to Greentech Media, successful solar companies will have addressed three important development criteria: the product serves an addressable market; it uses a low-cost, easily reproducible manufacturing technology; and it provides tangible value to the end user.

Solar Incentives

In the U.S., utilities were not able to take advantage of tax cuts until the recent bailout, but now they can be granted incentives just like businesses. "It also helps that it's fairly easy for utilities to get a hold of funding," said Mehta. "Some of the largest U.S. projects were announced last year in conjunction with Pacific Gas and Electric; this is helping the U.S. to become a major solar market."

An April 2009 report by Greentech Media ("PV Innovation in North America") offered a look at the reasons behind this positive shift in U.S. solar: "Unlike the majority of European and Japanese PV companies, North American PV companies emerged largely independent of government support. As a political climate favorable toward renewable energy takes hold in the United States, government support combined with traditional sources of private capital will engender industry growth unseen in other leading global PV markets."

It appears the sky's the limit when it comes to the future of solar. wbm

SidebStimulus Legislation has Something New for Solar

The federal incentive to purchase a solar system has become more attractive due to an amendment in the President's new stimulus legislation. The former 30 percent tax credit is now being offered in the form of a grant in hopes of drawing back some of the solar interest that has slipped during the current economic slump.

The grant, which will not be included as part of gross income for tax purposes, can be applied to commercial installations occurring before 2011 (non-profits and government agencies are not eligible). Solar system owners can receive their grant checks as soon as 60 days after installation or application (whichever is later).

"Many of the energy provisions in the stimulus, including the grant option, are designed to address the recent decrease in the number of active institutional investors for solar tax incentives," said Jason Vargelis, an attorney with an emphasis on tax credits with Carle, Mackie, Power & Ross in Santa Rosa, California.

Vargelis said that most organizations have had a positive response to the grant option. "The grant will make direct ownership of solar equipment more attractive to for-profit organizations that have resources to pay for, or finance, the up-front solar facility cost," he said.