What Are the Different Methods of Solar Power Generation?
General Reference (not clearly pro or con)
The Natural Resources Defense Council (NRDC ) stated the following in its article "Renewable Energy for America: Harvesting the Benefits of Homegrown, Renewable Energy," available at nrdc.org (accessed Aug. 2, 2013):
"The sun's energy can be captured to generate electricity or heat through a system of panels or mirrors.
Solar, or photovoltaic, cells convert sunlight directly into electricity. Most photovoltaic cells are made primarily of silicon, the material used in computer semiconductor chips, and arranged on rectangular panels. When sunlight hits a cell, the energy knocks electrons free of their atoms, allowing them to flow through the material. The resulting DC (direct current) electricity is then sent to a power inverter for conversion to AC (alternating current), which is the form in which electric power is delivered to homes and businesses.
Solar thermal collectors use heat-absorbing panels and a series of attached circulation tubes to heat water or buildings.
Solar concentration systems use mirrors - usually arranged in a series of long, parabolic troughs, a large round dish, or a circle surrounding a 'power tower' - to focus the sun's reflected rays on a heat-collecting element. The concentrated sunlight heats water or a heat-transferring fluid such as molten salt to generate steam, which is then used conventionally to spin turbines and generate electricity.
Passive solar design is the creative use of windows, skylights and sunrooms, building site and orientation, and thermal construction materials to heat and light buildings, or to heat water, the natural way."
The National Renewable Energy Laboratory (NREL) stated the following in its article "Learning about Renewable Energy: Solar Photovoltaic Technology," available at nrel.gov (accessed Aug. 2, 2013):
"Solar cells, also called photovoltaic (PV) cells by scientists, convert sunlight directly into electricity. PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect…
Solar panels used to power homes and businesses are typically made from solar cells combined into modules that hold about 40 cells. A typical home will use about 10 to 20 solar panels to power the home. The panels are mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture the most sunlight. Many solar panels combined together to create one system is called a solar array…
Traditional solar cells are made from silicon, are usually flat-plate, and generally are the most efficient. Second-generation solar cells are called thin-film solar cells because they are made from amorphous silicon or nonsilicon materials such as cadmium telluride. Thin film solar cells use layers of semiconductor materials only a few micrometers thick. Because of their flexibility, thin film solar cells can double as rooftop shingles and tiles, building facades, or the glazing for skylights.
Third-generation solar cells are being made from variety of new materials besides silicon, including solar inks using conventional printing press technologies, solar dyes, and conductive plastics. Some new solar cells use plastic lenses or mirrors to concentrate sunlight onto a very small piece of high efficiency PV material."
The Massachusetts Executive Office of Energy and Environmental Affairs stated the following in its article "About Solar Energy: Passive Solar, Solar Thermal, and Photovoltaic," available at mass.gov (accessed Aug. 5, 2013):
"We are able to use the sun's vast energy to heat air and hot water, through passive solar design and active solar thermal systems, and to generate electricity… Although this energy is not available all the time, and the earth's protective atmosphere allows only some of it to reach the earth, it is still an integral renewable resource…
Passive Solar Design
Buildings can be designed to collect, store, and distribute solar energy as heat. Referred to as passive solar buildings, they maximize absorption of sunlight through south-facing windows and use dark-colored, dense materials in the building to act as thermal mass - they store the sunlight as solar heat (light colors are less effective for heat storage)…
Active solar thermal systems collect solar radiation to heat air and/or water for domestic, commercial, or industrial use. The collector for a solar hot water system is typically a 4 ft. x 8 ft. box structure that has a glass top with a black absorber underneath it to circulate water. As the water is pumped through the collector, it is warmed and then circulated through a large, insulated tank inside a building. The warmed water can then be used to provide heat or hot water to the building. A solar hot water system can comprise one or more solar collectors, which are mounted on either a pitched, south-facing roof or on the ground."
The International Renewable Energy Agency (IREA) stated the following in its June 2012 working paper, "Renewable Energy Technologies Cost Analysis Series: Concentrating Solar Power," available at irena.org:
"Concentrating solar power (CSP) is a power generation technology that uses mirrors or lenses to concentrate the sun’s rays and, in most of today’s CSP systems, to heat a fluid and produce steam. The steam drives a turbine and generates power in the same way as conventional power plants…
CSP plants can be broken down into two groups… Line-focusing systems include parabolic trough and linear Fresnel plants and have single-axis tracking systems. Point-focusing systems include solar dish systems and solar tower plants and include two-axis tracking systems to concentrate the power of the sun…
The parabolic trough collectors (PTC) consist of solar collectors (mirrors), heat receivers and support structures. The parabolic-shaped mirrors are constructed by forming a sheet of reflective material into a parabolic shape that concentrates incoming sunlight onto a central receiver tube… A heat transfer fluid (HTF) is circulated through the absorber tubes to collect the solar energy and transfer it to the steam generator…
Solar tower technologies use a ground-based field of mirrors to focus direct solar irradiation onto a receiver mounted high on a central tower where the light is captured and converted into heat. The heat drives a thermo-dynamic cycle, in most cases a water-steam cycle, to generate electric power."