Solar energy is an inexhaustible resource. The sun produces vast amounts of renewable solar energy that can be collected and converted into heat and electricity.
Texas, due to its large size and abundant sunshine, has the largest solar energy resources among the states. Several other states, however, lead the nation in terms of using solar energy, mostly due to state policies and incentives that encourage the installation of solar energy systems.
California is the nation’s largest solar energy market by far, and has effective state initiatives promoting the industry. Other states with notable markets for solar energy include New Jersey, Arizona, Colorado and New York.
Even so, in 2006 solar energy accounted for just 0.01 percent of all U.S. electricity, mainly because of its higher costs compared to other power options. Solar energy plays an even smaller role in the Texas electricity market.
Still, Texas has the sunshine, manufacturing base and research institutions needed to become a leader in the development of solar energy. The state is well positioned to compete with other states and countries in a global solar energy market worth $10.6 billion in 2006. One study estimates that Texas could capture about 13 percent of all new jobs and investments related to solar photovoltaic technologies by 2015, primarily in manufacturing.
Humans have harnessed the power of the sun for millennia. In the fifth century B.C., the Greeks took advantage of passive solar energy by designing their homes to capture the sun’s heat during the winter. Later, the Romans improved on solar architecture by covering south-facing windows with clear materials such as mica or glass, preventing the escape of solar heat captured during the day.
In the 1760s, Horace de Saussure built an insulated rectangular box with a glass cover that became the prototype for solar collectors used to heat water. The first commercial solar water heaters were sold in the U.S. in the late 1890s, and such devices continue to be used for pool and other water heating.
In the late 19th century, inventors and entrepreneurs in Europe and the U.S. developed solar energy technology that would form the basis of modern designs. Among the best known of these inventors are August Mouchet and William Adams. Mouchet constructed the first solar-powered steam engine. William Adams used mirrors and the sun to power a steam engine, a technology now used in solar power towers. He also discovered that the element selenium produces electricity when exposed to light.
In 1954, three scientists at Bell Labs developed the first commercial photovoltaic (PV) cells, panels of which were capable of converting sunlight into enough energy to power electrical equipment. PV cells powered satellites and space capsules in the 1960s, and continue to be used for space projects.
In the 1970s, advances in solar cell design brought prices down and led to their use in domestic and industrial applications. PV cells began to power lighthouses, railroad crossings and offshore gas and oil rigs.
In 1977, solar energy received another boost when the U.S. Department of Energy created the Solar Energy Research Institute. It was subsequently renamed as the National Renewable Energy Laboratory (NREL), and its scope expanded to include research on other renewable energy sources. NREL continues to research and develop solar energy technology.
In the last 20 years, solar energy has made further inroads and now is used extensively in off-grid and remote power applications such as data monitoring and communications, well pumping and rural power supply, and in small-scale applications such as calculators and wristwatches. But solar energy has not yet achieved its potential to become a major contributor to world electrical grids.
Private and government research and development in solar energy technologies have led to continuing innovation over the last 30 years. The conversion efficiency of PV cells – that is, the percentage of sunlight hitting the surface of the cell that is converted to electricity – continues to improve. Commercially available cells now on the market have efficiencies approaching 20 percent. Cell efficiencies achieved in research laboratories recently surpassed 40 percent.
The worldwide PV market has grown by an average of 30 percent annually for the past 15 years, an increase that has improved economies of scale for manufacturers. As a result, the cost of electricity generated from PV modules has fallen significantly, from more than 45 cents per kilowatt hour (kWh) in 1990 to about 23 cents per kWh in 2006. In 2006 and 2007, a shortage of silicon (a primary component of crystalline silicon PV systems) temporarily increased PV module costs, but prices are expected to decline once again between 2008 and 2011, when silicon plants currently under construction are completed.
Solar energy has many uses. It can be used to provide heat, light or to generate electricity. Passive solar energy refers to the collection of heat and light; passive solar design, for instance, uses the sun’s energy to make homes and buildings more energy-efficient by eliminating the need for daytime lighting and reducing the amount of energy needed for heating and cooling. Active solar energy refers to storing and converting this energy for other uses, either as photovoltaic (PV) electricity or thermal energy.
Solar systems that heat water for homes and businesses, and passive solar design for buildings of all sizes, both have the same effect on the electric grid as conservation. They do not generate electricity per se, but reduce the demand for electricity and natural gas.
From 1998 to 2005, the solar water heating market produced about the thermal equivalent of 124,000 megawatt-hours (MWh) annually.13Solar pool heating is the most commonly used solar energy in the U.S. In 2005, it accounted for 95 percent of U.S. solar thermal collector shipments. The second-largest end use for solar thermal collectors was water heating, primarily in residential buildings, accounting for about 4 percent of U.S. shipments in 2005.
Solar energy technology is used on both small and large scales to produce electricity.
A unique advantage of small-scale solar energy systems is that, if they include storage devices, they may eliminate the need to connect to the electric grid. PV systems power road maintenance and railroad warning signs, flashing school zone lights, area lighting and other devices without expensive power lines or batteries. Offshore oil rigs, navigational aids, water pumps, telecommunication equipment, remote weather stations and data logging equipment also benefit from PV power.
In 2005, small-scale, off-grid PV-powered devices accounted for about 15 percent of PV capacity installed worldwide. In the same year, most installed PV systems – 59 percent – provided electricity to homes and buildings connected to the electrical grid. The remaining PVsystems were installed for use in remote off-grid homes and buildings in industrialized countries and the developing world.
On a larger scale, solar technology can produce commercially significant amounts of electrical power. Utility-scale concentrating solar power (CSP) systems, for instance, typically offer capacities of from 50 to 200 megawatts (MW), and could produce enough electricity to power approximately 7,800 to 31,000 homes in Texas, based on average electric use in 2006, when the sun is shining.
In 2006, global solar industry revenues were $10.6 billion. Texas specific data for solar industry revenues are not available. The IC2Institute expects the solar industry to create more jobs and contribute billions of dollars in investment and income to the U.S. economy over the next decade, if long-term incentives are offered to encourage the solar industry. An IC study noted that:
…since high-tech manufacturing employment in Texas has yet to return to pre-recession levels, the PV manufacturing industry creates an opportunity to generate employment for semiconductor and electric component workers statewide whose jobs have been outsourced offshore.
One study that evaluated the state-by-state impact of an expanding U.S. solar PV market found that California and Texas stand to gain a large share of all new solar PV jobs and investment created between 2004 and 2015. The study assumed that the nation’s solar PV capacity would grow from 340 MW in 2004 to 9,600 MW total PV capacity in 2015, with an investment value of $34 billion. According to this study, Texas should gain about 13 percent of all new U.S. solar PV jobs and investment, primarily in manufacturing. This translates into approximately 5,567 new jobs – 93 percent in manufacturing and 7 percent in construction/installation – and represents about $4.5 billion of investment in Texas by 2015.
The Solar Energy Industries Association (SEIA) estimates that “every megawatt of solar power currently supports 32 jobs, with 8 of these jobs in system design, distribution, installation and service created where the systems are installed.” The Prometheus Institute, a data source on solar energy initiatives, projects that solar energy will create 22,000 American jobs in manufacturing, distribution and various building trades over the next decade.
Austin Energy, a municipal utility, commissioned a study of the economic benefits of solar energy manufacturing and installation in 2006. This study concluded that construction of a 100 MW solar manufacturing plant in the Austin area could create nearly 300 new jobs and add about $1 billion to the regional economy by 2020. In addition, the city of Austin and Travis County would benefit from an increase in sales tax and property tax revenue.
Texas technology companies have demonstrated an interest in the solar industry. In Austin, HelioVolt has developed a low-cost manufacturing process for applying a thin-film PV coating to building materials. On April 15, 2008, Governor Rick Perry announced that HelioVolt would receive $1 million from the state’s Texas Enterprise Fund (TEF) for the construction of a development and manufacturing facility. According to the Governor’s office, the project is expected to create about 160 jobs and $62 million in capital investment.
Entech, located in Keller, Texas, provides advanced solar energy technology including high-efficiency solar cells for NASA spacecraft. The company also has invented a new lighting system to illuminate office buildings, schools and stores. In addition, Applied Materials, which has a semiconductor manufacturing plant in Austin, recently acquired a company called Applied Films in order to enter the PV business. Applied Materials plans to use its chip-industry knowledge to drive down manufacturing costs for solar panels.
The IC2 Institute notes that the solar industry could produce substantial savings for Texas energy consumers in the form of “avoided generation capacity capital costs, avoided fuel costs, avoided CO2 emissions, the value of fossil fuel price hedging and avoided distribution costs.” In California, IC estimated that these savings ranged from eight to 22 cents per kWh in 2005. IC says that further research is needed to estimate similar savings for Texas consumers.
Solar energy also can reduce price volatility related to fluctuating natural gas prices. As utilities begin to charge higher rates for peak load periods, PV systems that generate the most electricity during the hottest time of the day can produce substantial savings on energy costs. Utility companies would benefit because additional peak load power reduces the strain on their systems and the need for additional power plants.
Sunlight can be converted into heat and electricity in a number of ways. A variety of solar technologies are in production, and many companies and researchers are pursuing efforts to develop devices that convert the sun’s energy more efficiently.
Photovoltaic cells (PV) are used worldwide to convert sunlight into electricity. The PV cell contains two layers of semiconducting material, one with a positive charge and the other with a negative charge. When sunlight strikes the cell, some photons are absorbed by semiconductor atoms, freeing electrons that travel from the negative layer of the cell back to the positive layer, in the process creating a voltage. The flow of electrons through an external circuit produces electricity.
Since individual photovoltaic cells produce little power and voltage – they generate only about one to two watts per cell–they are connected together electrically in series in a weatherproof module. To generate even more power and voltage, modules can be connected to one another to form a solar panel; solar panels are grouped to form anarray. The ability to add additional modules as needed is a significant advantage of PV systems.
Several PV technologies are in use or in development. The silicon-based PV cell, made with the same silicon used in the semiconductor industry, has dominated the market and continues to do so. Solar Energy Industries Association (SEIA) reports that 94 percent of PV modules used today are made of crystalline silicon.
The search for cheaper solar energy systems, however, has spurred the development of thin-film PV cells that have semiconductor layers only a few millionths of a meter thick. Thin-film PV technologies are intended to reduce the amount of expensive materials needed to produce solar cells. For example, new methods are being used to produce solar cells that reduce or eliminate the use of high-priced silicon. The U.S. Department of Energy (DOE) estimates that U.S. production of thin-film solar modules will exceed that of crystalline silicon modules by 2010. While thin-film efficiencies are lower than silicon’s, the lower cost may tip the balance in thin film’s favor.
Research scientists also are working on a new generation of solar cells that include nanomaterials, multijunction cells and various other research efforts that may produce “leapfrog” technologies, offering considerably higher efficiency at a lower cost.
Nanotechnology, for instance, has attributes that, in theory, may triple the amount of energy produced by photons of sunlight. This technology also could result in PV cells that could be painted on homes and buildings. Research on inverted multijunction cells that capture more of the sun’s energy also is ongoing, and already has produced a world-record 39.3 percent conversion efficiency. These emerging technologies have the potential to produce higher efficiencies more cost-effectively.
Some companies are developing faster and more efficient ways to manufacture thin-film solar cells at lower costs. HelioVolt, an Austin-based company, has developed FASST, which it claims is a low-cost manufacturing process for applying copper indium gallium selenide, a thin-film PV coating, to construction materials such as roofing, steel and flexible composites in 80 to 98 percent less time than conventional processes. This would position the company to bring economical building products featuring integrated PV cells to the market. HelioVolt is seeking partners and plans to have some products available by 2008.
The U.S. Army also is interested in lightweight solar panels, since it wants to reduce the need for generators and personal battery packs that soldiers use to power fans, light, radios and laptops. In Texas, the Army’s Fort Bliss, in cooperation with the U.S. Naval Postgraduate School and Army Corps of Engineers, is the site for a “Power The Army” project that will conduct large-scale field trials of three new solar energy technologies. The army and others hope that the project will improve solar system efficiencies and lead to lower solar energy costs.
Solar Thermal Energy
Solar thermal energy refers to technologies that use the sun’s energy to heat water and other heat-transfer fluids for a variety of residential, industrial and utility applications. Simple and widely used applications of solar thermal energy include solar water heating, swimming pool heating and agricultural drying. In the U.S., solar pool, water and space heating are currently the major applications of thermal energy.
Solar thermal energy refers to technologies that use the sun’s energy to heat water and other heat-transfer fluids for a variety of residential, industrial and utility applications.
Flat-plate collectors – large, insulated metal boxes with glass or plastic covers and dark heat-absorbing plates – are the most common collectors used for home solar water and space heating. Other common varieties are evacuated-tube collectors and integral collector-storage systems. All three types gather the sun’s energy, transform it to heat and then transfer that heat to water, a heat-transfer fluid or air. Flat-plate collectors typically are mounted on the roof. Evacuated-tube collectors are sometimes used to heat water, but also have useful commercial and industrial applications where higher temperatures are required.
The most powerful large-scale solar thermal technology, however, is concentrating solar power (CSP). While CSP can be PV-based, it generally refers to three solar thermal systems–parabolic troughs, solar dish/engines and power towers–each of which is in use or under development today. These systems use mirrors or reflectors to focus sunlight to heat a fluid and make steam, which then is used to generate electricity.
At present, only parabolic trough CSP systems are in commercial use in the U.S., with three installations in three states capable of generating 419 MW of electricity in all.45Trough systems consist of a linear, parabolic-shaped reflector that focuses the sun’s energy on a receiver pipe, heating a transfer fluid flowing through the pipe; the transfer fluid then generates superheated steam which is fed to a turbine and electric generator to produce electricity. The troughs track the sun from East to West during the day so that the sun is continuously focused on the receiver pipes.
A solar dish/engine system consists of a solar concentrator – glass mirrors in the shape of a dish that reflect sunlight onto a small area – and a power conversion unit that includes a thermal receiver and a generator. The thermal receiver includes tubes for the transfer fluid – usually hydrogen or helium – that transfers heat to a generator to produce electricity. In 2006, Stirling Energy Systems, a Phoenix-based provider of such systems, signed agreements to build two large plants employing the technology in Southern California. This would be the first commercial installation of a solar dish/engine system in the U.S.
In the U.S., two large-scale power tower demonstration plants – Solar One and Solar Two located in the Mojave Desert near Barstow, California – have generated 10 MW of electricity each. Solar One operated off and on from 1982 to 1988 and used water as its heat transfer fluid, while Solar Two used molten nitrate salt for heat transfer, operating periodically from 1996 to 1999.
Europe’s first commercial solar power tower went online in Spain in late 2006 and currently generates 11 MW of electricity, enough to power just under 6,000 homes. More fields of mirrors are being added to this plant. Solucar, its developer and operator, plans two more power towers at other locations in Spain.
Solar energy differs from most energy technologies in that it can be generated on site, reducing or eliminating fuel transportation and electricity transmission and distribution costs. Solar water heating and space heating devices are “stand-alone” systems that are not connected to the electric grid. A PV system provides electric power directly to a user and can be used either as a “stand-alone” power source or connected to the electricity grid .
|System||Energy Source||Connected to the electricity grid?||Energy storage device in the system?||Examples|
|Grid-tied* solar system||PV cells||Yes||No||Home system that draws on the electricity grid at night and exports excess power in the day|
|Stand-alone grid- tied* solar system||PV cells||Yes||Yes (batteries)||Home or business system uninterruptible power (e.g. for computers, servers). Still operates when the grid is down|
|Stand-alone solar system without energy storage||PV cells||No||No||Water pumping|
|Stand-alone solar system with energy storage||PV cells||No||Yes (batteries)||Remote homes, lighting, TV, radio, telemetry|
|Stand-alone off-grid hybrid solar system||PV cells in combination with another energy source**||Most often not||No||Remote large-scale communications, industrial uses|
* also called “grid-connected.”
**such as diesel or wind
Systems offering this flexibility sometimes are called distributed power generators. By contrast, utility-scale concentrating solar power plants use centralized power plants and transmission lines to distribute electricity to customers.
In 2005, off-grid PV systems accounted for about 18 percent of all PV installed worldwide. Homes in remote areas can use PV systems for lighting, home appliances and other electrical needs, saving the cost of extending power lines to a remote location. These systems require a storage device to store power generated during the day for nighttime use; typically, this is a lead-acid battery bank. Unlike gasoline-powered generators, PV systems do not require fuel deliveries and are clean and quiet to operate.
Distributed, Grid-Tied PV
At night and even on cloudy days, a PV system is not likely to produce enough energy to power a home’s needs, while on sunny days it may produce more electricity than needed. A home or business with a PV system that is connected to the electric grid has the option of supplementing its energy needs with electricity from the local utility company and delivering excess electricity to the grid. Grid-tied PV systems thus can reduce strains on the power grid.
Solar energy is available everywhere on Earth, in varying amounts. Solar radiation that reaches the earth’s surface in an unbroken line is called direct, while sunlight scattered by clouds, dust, humidity and pollution is called diffused. The sum of the direct and diffuse sunlight is called global-horizontal insolation. Concentrating solar technologies, which use mirrors and lenses to concentrate sunlight, rely on direct radiation, while PV cells and other solar technologies can function with diffused radiation.
Insolation is a term referring to the amount of solar radiation that strikes the planet’s surface over some period – a minute, hour, day, month or year. NREL has developed insolation estimates for the U.S. based on solar measurements taken at a number of stations throughout the country, as well as computer modeling that uses meteorological data to predict insolation at a large number of sites.
According to NREL’s measurements, the nation’s most plentiful solar resources are found in the Southwest. California, Nevada, Arizona, New Mexico, Utah, Colorado and Texas, and they possess some of the best insolation values in the world. According to DOE, “enough electric power for the entire country could be generated by covering about nine percent of Nevada – a plot of land 100 miles on a side – with parabolic trough systems.”
In all, the U.S. has a relatively abundant supply of solar resources. A 1 kW solar electric system in the U.S. can generate an average of more than 1,600 kWh per year, while the same system in southern Germany (which installs eight times as many PV systems as the U.S.) would be able to generate only about 1,200 kWh per year, due to that nation’s weaker insolation. A 1 kW system installed in parts of Nevada, Arizona, New Mexico and far West Texas can produce 2,100 kWh per year.
Texas has abundant solar radiation statewide, but again, the highest insolation readings are in West Texas. West Texas has 75 percent more direct solar radiation than East Texas, making it an ideal location for utility-scale CSP technologies. Virtually all of Texas, however, has adequate to very good solar radiation.
A study commissioned by the State Energy Conservation Office (SECO) in the mid-1990s found that Texas has 250 “quads” of solar energy accessible per year. Given that one quad is one quadrillion British thermal units (Btus) of energy – enough to meet the annual needs of about 3 million people – Texas’ solar energy potential is enormous. The 2007 Texas Legislature directed SECO to update a 1995 assessment of Texas renewable energy resources. This report, which will be released before the start of the 2009 Texas Legislative Session, will include up-to-date data on the availability of various renewable energy resources.
While the U.S. possesses some of the world’s best solar radiation values, it accounted for only 8 percent of worldwide PV installations in 2006. Germany was the undisputed leader in that year, accounting for 55 percent of the world market. Japan came in second place, with 17 percent of the PV world market. Spain’s PV installations rose by more than 200 percent in 2006, while the U.S. market expanded by 33 percent.
The U.S. was once a leader in the PV market, but over the last decade it has lost ground to Japan and Germany. Both governments offer generous subsidies to stimulate their solar energy markets. The U.S. has not offered similar subsidies at the federal level, and has not established a long-term, consistent strategy in its approach to solar energy at either the state or federal levels, creating periodic uncertainty in the market.
Costs and Benefits
Both thermal and PV solar systems can produce electricity at significantly lower costs today than in the 1980s, but costs remain high compared to fossil fuel energy sources.
In the U.S., 2006 retail electricity prices for all sectors averaged more than eight cents per kWh, and for residential electricity, the price averaged about 10 cents per kWh. By contrast, parabolic trough-style CSP systems generated electricity at a cost of 12 cents per kWh in 2006, while PV systems generated electricity for about 18 to 23 cents per kWh.
The retail price of electricity during peak hours, however, can rise to between 25 and 40 cents per kWh in some parts of the U.S., making PVsystems more competitive during peak periods. PV systems usually generate more electricity during the hottest time of the day, and thus can help to offset the need to add expensive electric generating capacity to satisfy peak demand in warm areas of the country.
PV costs per kWh declined significantly over the last 16 years (from more than 45 cents per kWh in 1990 to about 23 cents per kWh in 2006), due primarily to manufacturing economies of scale as well as improved solar cell efficiency.79 The Solar Energy Industries Association (SEIA) notes that “each doubling in cumulative manufacturing has brought prices down by about 18 percent.”
In the past five years alone, the world PV industry has grown by an average of 30 percent or more each year. In 2006, the U.S. PV industry expanded by 33 percent, compared to 19 percent for the world. The expansion of federal income tax credits for commercial and residential solar energy projects, and state and utility incentives, particularly in California, fueled the U.S. industry’s impressive growth in 2006. These federal tax credits, however, are set to expire at the end of 2008, and were not extended by Congress in 2007.
A shortage of silicon and growing global demand for solar PV modules led to some cost increases in 2006 and 2007. About 90 percent ofPV modules today still are made of crystalline silicon (polysilicon), which has been in short supply globally, constraining production and temporarily increasing the cost of solar cells.
Polysilicon supplies are expected to remain tight and prices high until new plants under construction are completed. Solarbuzz, an international solar energy consulting firm, predicts rapid growth in polysilicon capacity through 2011, and a resumption of faster rates of growth for the PV market. Unprecedented investment in manufacturing capacity is expected to result in lower PV costs over the long term.
The cost of solar modules accounts for 50 to 60 percent of the total installed cost of a PV system, with other system parts, materials, assembly and installation accounting for the remainder. PV module costs have declined by about 80 percent over the last decade, but the installation costs have not dropped appreciably in recent years. Installation costs vary depending on available sunlight, the typical energy usage of the home and the availability of experienced installers in the area.Unlike other energy sources, however, 90 percent of the cost of a PV system is incurred up front. Once the system is installed, there are no fuel costs and the system requires little maintenance.
A PV system designed to supply about 60 percent of the energy needs of a home in California costs about $16,000 to $22,000, minus any tax credit or rebate. In San Diego, California, the federal income tax credit (see below) and a California Solar Initiative (CSI) rebate have reduced the total installed cost of a $17,460 residential PV system by $7,000, for a final cost of $10,460. Solarbuzz notes that government incentive programs can lower solar PV system costs to about 10 to 12 cents per kWh, compared to a range of 22 to 40 cents per kWh without incentives.
The PV industry’s overarching goal is to improve solar cell efficiency while reducing their cost. Government research labs and private companies have invested in research and development in the expectation of a breakthrough that will make solar energy competitive with other sources of energy.
Solar cell efficiencies have improved significantly since the 1950s, when they had efficiencies of less than 4 percent. Today, solar cell efficiencies range from 15 to more than 30 percent, but most commercial PV systems are about 15 percent efficient. In December 2006, Boeing-Spectrolab Inc., manufacturer of space solar cells and panels, announced that, with funding, it had developed a solar cell with a conversion efficiency of 40.7 percent. This “multi-junction” solar cell uses a new class of semiconducting materials that allows it to capture energy from more of the solar spectrum. This breakthrough may lead to less expensive, more efficient solar cells.
Price Trends for Solar Power Through 2015 Photovoltaics and Concentrating Solar Power (CSP)
|18 to 23 cents per kWh||12 cents per kWh|
|11 to 18 cents per kWh by 2010||8.5 cents per kWh by 2010|
|5 to 10 cents per kWh by 2015||6 cents per kWh by 2015|
Source: U.S. Department of Energy.
DOE expects significant PV and CSP cost reductions in the next five to 10 years, making these solar technologies more competitive with conventional fuel sources. Improved PVtechnologies that use cheaper materials, higher-efficiency devices, new nanomaterials applications and advanced manufacturing techniques should reduce the cost of PV-generated electricity to as little as 11 cents per kWh by 2010. DOE also expects CSP-generated electricity prices to decline to 8.5 cents per kWh by 2010. Texas’ average residential retail price for electricity was more than 12 cents per kWh in 2006 and 2007.
In addition to cost, however, solar electricity faces other barriers to widespread market deployment. As a new entrant to the power supply market, PV developers face uncertain and inconsistent treatment, both in Texas and nationally, at the hands of regulators and electric utility companies. Processes and rules for interconnection and net metering are not consistent throughout Texas, so development of a statewide marketplace for these technologies has proven difficult. Solar industry professionals want clear, consistent market rules to encourage the development of a single market and the jobs and economic benefits that arise from it.
A federally funded study at the University of Massachusetts-Amherst found that experts in solar technology agree that subsidies alone are not enough to support a healthy solar industry; more investment is needed from the manufacturing sector. Recently, the number of private equity firms and venture capitalists investing in the solar energy sector has grown rapidly, as has the number of companies working on various solar technologies.
A 2007 report by the IC2 Institute indicated that California leads the nation in U.S. federal research awards, patents, scientific publications and business establishments related to PV solar energy. Texas ranked fourth among states in its number of federal research awards related to PV – 18 to California’s 62 – with half going to industry and half to educational institutions. Texas accounted for 3 percent of the U.S. scientific literature on photovoltaics, behind California, Colorado, Ohio, New York and Massachusetts. In its number of PV-related patents, Texas ranked fourth, again behind California. And Texas ranked fifth in the number of PVbusinesses located in the state.