Materials and Technologies for Solar Energy

The development of alternative energy has become a major effort of many economies and companies. The impetus for this investment in capital and research has several major facets, including the following:

• Fossil fuels are limited in supply and countries wish to limit exposure to energy cost swings and supply variations.
• The burning of fossil fuels is releasing carbon dioxide into the atmosphere and this is increasingly being linked to climate change.

While quite different motivations, these are both strong drivers for the search for new sources of energy that are renewable and as close to carbon neutral as possible.

The fact that the supply of fossil fuels is finite has become ever more obvious and concern over greenhouse gas emissions and their effect on climate change has intensified. As a result, interest in alternative forms of energy has increased. Although the recent variation in the cost of petroleum from record highs through a record decline to a state of uncertainty has tempered these concerns, "green," renewable fuels are still items of intense interest. The President of the United States has indicated that investments will still continue, at least in the United States.

A major underpinning of the solar industry is the various economic incentives provided by government programs and regulations. Without these actions, and particularly with the currently depressed price of petroleum, solar energy would be facing severe economic hurdles. Countries such as Germany, Japan, Spain, and the United States have encouraged solar energy to flourish with subsidies.

"Green" energy sources are many, but several have received the most attention, including wind, biofuels and solar. Interest in these is high since most regions of the world where there are large population concentrations have some access to these forms of energy or may be able to develop them. Other important new supplies include geothermal and various ocean-derived energies (e.g., thermal gradient, tidal). While each of these technologies is considered a viable alternative to traditional fossil fuels, each has limitations.

Solar energy is generally regarded as quite clean. Once the equipment is manufactured and placed into service, the variable costs—that is, raw materials—required to run these systems over the course of thirty years are minimal. Of course, climatic conditions affect the areas where it will be most economically advantageous to install, namely regions where there is abundant sunshine such as the desert zones of the world between the temperate and subtropical regions.

Solar energy is derived in two general ways. The energy of the photons from the sun interacts with complex chemical materials to generate an electric potential that can be harvested as electrical energy. This is photovoltaic (PV) solar energy. Alternatively, the photons may interact with surfaces to generate thermal heat, which can be used beneficially in several ways; it can be used to generate steam and drive electric turbines or the heated elements can supply heated water for direct heating. This thermal application has been in use for centuries, and today the technology is used primarily in large-scale applications, in part due to economies of scale and cost benefits.

The following pie chart shows the PV market by region in 2008.

Sources: European Photovoltaic Industry Association; German Solar Industry Association; SRI Consulting*.

Generation of solar power, like so many new energy generation processes is chemical dependent. Whereas biofuels require a constant stream of biomass and chemical raw materials, solar energy makes demands on chemicals during the manufacture of photovoltaic cells. This is a major source of demand for various forms of silicon and several relatively rare transition metals and metalloid elements. Many chemical products are used including inorganic chemicals and metals, adhesives for cell formation, solvents for some new thin film application technologies, nanoparticles, plastic films for substrates, antireflective coatings and various complex organic molecules for dye-sensitized cells and organic cells. Thermal solar energy also requires chemicals, primarily for heat transfer media. There is an initial load requirement as well as make-up media and other materials.

No longer is solar energy used solely for small consumer electronics and powering space satellites. Rather, the technology is now used on a much larger scale. The most prevalent type of solar energy technology is the photovoltaic cell. Silicon, used primarily in first- and second-generation solar cells, is currently the most efficient and popular material used in photovoltaic technology. Research is focused on newer-generation materials using such elements as indium, gallium, tellurium, molybdenum, cadmium and a host of organic materials instead of silicon. There are several reasons for this, but they can generally be summed up in one word—cost. Traditional silicon cells are expensive whereas the newer cells are generally cheaper on a cost per unit of electricity generated basis.

The following chart shows the estimated generation of solar power by the type of generating technology:

Source: SRI Consulting*.
*IHS is permitted by SRI to continue using the SRI Consulting name and trademarks on relevant historical reports published prior to April 1, 2012.

While the specific technologies for producing photovoltaic cells are almost as numerous as the number of companies participating in the industry, especially with newer-generation technologies, general manufacturing schemes and cell structures exist. Of the available PV cell types, silicon cells remain the dominant force in the solar energy market.

In the future, it may become necessary to seek alternatives to traditional energy sources in order to meet global demand for energy. While coal, petroleum, and natural gas are relatively abundant currently, the costs, both fiscally and environmentally, of using these resources may prove to be too much of a burden upon the consumers of energy. Thus, alternatives to these forms of energy must be researched and marketed. Solar power is one such form of energy. While it presents a clean alternative environmentally to fossil fuels, it cannot compete with them on a price basis because of their production and raw material costs. Thus, in order for solar power to become an economically viable alternative to fossil fuels, a considerable amount of resources, both from the public and private sectors, will be necessary in order to promote technology with higher efficiencies and lower costs. Only when this has been achieved will solar power increase its market share in the global energy market.

This 161-page report provides a detailed overview of the technologies (first-, second-, and third-generation, with a brief discussion of fourth-generation) and materials used in the production of solar cells, their current markets and outlook, and key producing companies for each technology.

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