Because it is a virtually unlimited, clean, and renewable resource, the sun has the potential to provide an important source of energy to help power our way of life. Interest in solar energy is growing among generation scale electric producers in Ohio and throughout the United States. Solar energy systems are quiet, dependable, contain no moving parts, and produce no pollutant emissions, which is a tremendous advantage.
Historically, our major sources of energy have consisted of coal, oil, and natural gas. In Ohio, for instance, 87% of our electricity is generated from coal. These energy sources originated from ancient plants and animals, and the energy that comes from plants' absorption of sunlight and conversion of this sunlight into energy (photosynthesis). Therefore, most of the fossil fuel energy sources we utilize today, originated from harnessing the sun's solar energy. By streamlining today's current solar technologies, we are able to maximize the sun's resource by directly converting its energy into heat or electricity. According to the National Renewable Energy Laboratory, "more energy from the sun falls on the earth in one hour than is used by everyone in the world in one year." In 2008, Germany produced 39% of the world's total cumulative solar capacity (MW) followed by Spain at 24% and the United States at 8% (U.S. Department of Energy, Alliance for Sustainable Energy, LLC, 2009).
Like many other locations in the United States, Ohio possesses exceptional solar potential, with an annual average solar resource of roughly 1600 kWh/kW of solar energy. In comparative terms, Ohio's solar resource would be similar to that of Spain. Furthermore, advancements in thin film photovoltaic technology continue to compliment the climate in Ohio, thus making solar more viable than ever.
Solar Benefits to Utilities
Public awareness of environmental impacts and benefits, new energy policies, and advancements in research and development are all factors that are continually reshaping the solar industry as a whole. Generation scale solar energy offers a number of significant benefits to utilities who are constantly evolving with the complex issues of today's energy landscape. Some of these benefits include the following (Pernick and Wilder, 2008):
- Solar power can offer a price hedge against volatile and increasing costs for fossil-fuel resources like coal and natural gas. Once installed, solar power provides stable fixed prices to utilities and users.
- Solar power is becoming a cost-effective peak generation resource.
- Within a decade, solar power will be cost-competitive in most regions of the United States on a kilowatt-hour (kWh) basis.
- Compared to coal, nuclear, and gas-fired power plants, solar power has no fuel costs, low maintenance costs, and will provide credits, rather than costs, in a carbon-regulated world.
- Solar Photovoltaic is a widely available resource, suited to most locales around the nation.
- Solar Photovoltaic can ease congestion in regions where energy demands have stressed the grid.
Types of Technologies
There are two basic types of technologies currently used to produce generation scale electricity from solar energy: Solar Photovoltaic (PV) and Concentrating Solar Power (CP). Only one of the two, PV, is currently used as a generation scale energy source in Ohio.
Solar Photovoltaic Technology (PV)
PV technologies work by absorbing sunlight into photovoltaic panels that convert sunlight directly into electricity. When light hits the photovoltaic material, it dislodges electrons, creating movement. The movement of these electrons then generates an electric current (Komor, 2004). Solar energy systems can be installed anywhere the sun shines and are the least resource-constrained of all forms of renewable energies.
The major components of a commercial scale solar PV system consist of the following:
- Photovoltaic modules—These modules are the fundamental component of a solar system. The two most common types of PV modules are crystalline silicon and thin film. Crystalline silicon solar modules are made from silicon (which starts out as sand) and generally are more efficient than thin film panels. However, thin film modules are made with materials such as cadmium telluride and require much less material to manufacture. This ultimately reduces the cost of a thin film module in comparison to a traditional crystalline silicon module. Solar cells are combined into a unit that is typically bonded to glass, thus forming a PV module and enabling it to be framed and mounted.
- Post and Mounting Brackets—There are a number of factors (such as topographic layout, soil types, power grid infrastructure, and system size) that will impact the design of a solar system. As a result, there are countless ways solar systems can be planned and configured. However, each system will have a mounting system tailored to meet the needs of that specific project.
- Inverter—An inverter is required to convert the system's (DC power) direct current to match the power grid's (AC power) alternating current.
- Step-Up Transformer—This may be required to increase the voltage to that of the power grid.
PV solar technologies are extremely versatile and can power something as small as a wristwatch or as large as an entire community. Utility generation scale PV systems are now becoming more feasible as considerable efficiency improvements have been made, increasing the percent of sunlight falling onto a solar cell that is converted into electricity. Ultimately, these advancements in technology have extended the reach of solar power from high-intensity Sunbelt regions to virtually anywhere the sun shines.
Concentrating Solar Power
These technologies harness heat from the sun to provide electricity for large power stations. Many traditional power plants burn fossil fuels such as coal to heat and boil water, thus transforming it to steam. This steam is then used to turn a giant turbine that is attached to a generator, which generates electricity. Concentrating Solar Power (CSP) systems work in a similar manner to the traditional coal-fired power plant. However, instead of using coal to create steam, CSP systems use the sun.
CSP systems harvest the sun's energy using a system of collection mirrors. There are a number of different types of collection systems, such as linear trough systems, dish systems, and power tower systems. Regardless of which collection system is being used, the mirrors basically track the sun, channeling sunlight energy on collection tubes filled with a fluid inside. The hot fluid is then used to boil water into steam, ultimately turning a conventional steam-turbine generator to produce electricity. Essentially, the tubes serve as heat exchangers, using the sun's energy to produce heat and to run a power generator much like the traditional fossil fuel power generation plant (The Office of Energy Efficiency and Renewable Energy, 2013).
Larger, utility-scale CSP applications can provide hundreds of megawatts (MW) of electricity for the power grid. One significant advantage of CSP systems is their ability to harness and store the sun's heat throughout the day. This also allows CSP power plants to provide high-value dispatchable power at night when the sun is not shining. These attributes make CSP an attractive renewable energy option in the southwestern United States and other high-intensity sunbelts worldwide.
Generation Scale Solar in Ohio
On August 19, 2010, the PSEG Wyandot Solar Farm was dedicated to operation, representing Ohio's first generation scale solar plant feeding the power grid. The PSEG Wyandot Solar Farm is owned by PSEG Solar Source, a subsidiary of PSEG (NYSE: PEG). The solar generation facility consists of 159,200 ground-mounted PV thin-film solar panels on 83.9 acres adjacent to the Wyandot County Airport. Providing carbon- and pollution-free energy when the sun is shining, the 12-MW facility provides enough electricity to serve more than 9,000 homes (PSEG Solar Source LLC.). This landmark project represents the largest solar generation facility in the Midwest, and one of the largest east of the Mississippi River.
Future of Solar
Currently, solar power still represents a very small amount of the total U.S. energy supply generation, accounting for less than one-tenth of one percent of total energy generation. However, research performed by Clean Edge Inc. shows, "Solar power has been expanding rapidly, growing an average of 40 percent per year since the beginning of this decade. In the past five years, global solar installations have expanded more than fourfold from approximately 600 MW in 2003 to nearly 3000 MW (the equivalent of three conventional power plants) in 2008. Furthermore, research indicates that the solar contribution could be quite considerable, realistically reaching 10 percent of total U.S. electricity generation by 2025 by deploying a combination of solar photovoltaics and concentrating solar power" (Pernick and Wilder, 2008).
In summary, significant obstacles (such as current cost per kWh, inability to produce energy during evening hours, and the availability of PV panels relative to developer demand) to the utility scale solar generation projects still exist. However, there are many positive indicators (such as improvements in technology, reductions in cost per kWh, development of supportive policies and business models, and environmental awareness) for the advancement of solar power. Perhaps more importantly, there seems to be a fundamental change in our culture, which seems to be gravitating toward self-sustaining, alternative energy sources such as solar energy. This unified commitment from utilities, communities, developers, and consumers is vital to establishing a partnership approach toward the implementation and advancement of alternative energy sources in U.S. markets such as Ohio.
Komor, P. (2004). Renewable Electricity—Generating Technologies: Cost and Performance. In Renewable Energy Policy (pp. 39–40). Diebold Institute for Public Policy Studies.
Pernick, R., & Wilder, C. (2008). Utility Solar Assessment (USA) Study. Clean Edge.
Public Service Electric & Gas Company. (n.d.). PSEG Wyandot Solar Farm. Public Service Enterprise Group.
Solar Energy Industries Association. (n.d.). Solar Energy.
U.S. Department of Energy. (2013). Energy 101: Concentrating Solar Power Basics. Office of Energy Efficiency and Renewable Energy.
U.S. Department of Energy, Alliance for Sustainable Energy. (2009). Solar Energy Basics. National Renewable Energy Laboratory.
National Renewable Energy Laboratory (www.nrel.gov)
American Solar Energy Society (www.ases.org)
Solar Energy Industries Association (www.seia.org)