Solar Power/ Solar Panels
Solar thermal (solar water heater, solar heating)
Solar thermal devices use direct heat from the sun, concentrating it in some manner to produce heat at useful temperatures. The modern solar industry began with the oil embargo of 1973-1974 and was strengthened with the second embargo in 1979. The growth of the solar industry during this period of fuel shortages and high prices (1974-1984) soared from 45 solar collector manufacturing firms to 225 firms.The solar market was helped during this period by government assistance, both Federal and State. Currently, solar thermal devices do everything from heating hot water, swimming pools, space heating to creating steam for electricity generation. There are more than 10 million residential solar powered homes and commercial ones using solar thermal and solar electric technology in US. Learn more by clicking on the services section above.
Solar water heating has been around for many years because it is the easiest way to use the
sun to save energy and money. One of the earliest documented cases of solar energy use
involved pioneers moving west after the Civil War. They left a black pot in the sun all day to
have heated water in the evening.
The first solar water heater that resembles the concept still in use today was a metal tank that
was painted black and placed on the roof where it was tilted toward the sun. The concept
worked, but it usually took all day for the water to heat, then, as soon as the sun went down,
it cooled off quickly because the tank was not insulated.
Clarence Kemp of Baltimore patented the first commercial solar water heater in 1891. It was
called the Climax. The Climax had several cylindrical water tanks of galvanized iron that
were painted black. Kemp insulated the tanks in felt paper and placed them in a glass-
covered wooden box for better heat retention. This invention earned Kemp the “father of
solar energy in the United States” title.
Solar water heating improved the lives of homeowners, especially during the summer,
because it eliminated the need to heat water on the stove. Firing up the stove to heat water
warmed the entire house. In the winter, the solar water heater was drained to protect it from
freezing, and homeowners resumed heating water on the stove. Kemp claimed the Climax
could be used from early April through late October in Maryland. In southern California, it
could be used year-round. High-energy costs in California made using free solar energy even
more logical. By 1900, 1,600 Climaxes were installed in southern California.
A design by William Bailey in 1909 revolutionized the industry with the first flat-plate
collector. The most visible difference in his design was a separate collector and storage tank. The collector had a grid of copper pipes and was covered with glass. He added a metal
absorber plate to transmit the solar heat in the box to the water in the pipes. The storage tank
was insulated. Since these improvements kept the water warm morning and night, the solar
hot water heater was called the Day and Night collector. The system could be connected to a
backup gas heater, wood stove or coal furnace. An electric heater could be placed inside the
storage tank to heat the water automatically if it dropped below a preset temperature.
Bailey’s business grew until a freak cold spell hit southern California in 1913. Copper pipes
in the collectors froze and burst when the temperature dropped to 19 degrees Fahrenheit. He
solved this problem by placing nonfreezing liquid in the collector pipes. This liquid traveled
through a coil in the storage tank to heat the water. He sold more than 4,000 Day and Night
heaters by the end of World War I. The peak year was 1920 when more than 1,000 were sold.
Solar hot water heater sales decreased when natural gas prices dropped and gas companies
offered incentives, including free installation, to switch to gas. Bailey recognized the trend
and used his experience to produce gas water heaters. His company made its last solar water
heater in 1941.
California’s gas discoveries nearly put an end to solar water heating there, but this was not
the case in Florida where solar was the only way to heat water cheaply. The Solar Water
Heater Company was established in Florida in 1923. By 1925, Miami’s population had
increased to more than 75,000. Business flourished until Miami’s building boom subsided in
early 1926 and a hurricane struck the area in September. The plant closed shortly thereafter.
In 1931, the plant reopened with an improved collector. Charles Ewald changed the wooden
box to metal to last longer in Florida’s humid environment. He also insulated the box and
replaced the steel tubing with more durable and better conducting soft copper. He discovered
that soft copper withstood temperatures as low as 10 degrees Fahrenheit. Ewald added more
pipe and placed it strategically for optimum efficiency. His design produced hotter water in
greater volume. He called it the Duplex.
He also developed a method of matching the needs of the homeowner with the appropriately
sized collector and storage tank. This revived the industry in 1934. The following year, New
Deal legislation boosted home building and, in turn, the solar heating business. Inexpensive
FHA Home Improvement Loans stimulated the market. By 1941, nearly 60,000 hot water
heaters had been sold in Florida. About 80 percent of Miami’s new homes had solar hot
water heaters, and more than 50 percent of the city used them. Solar water heaters were also
used in north Florida, Louisiana and Georgia and in other parts of the world, including Japan.
No matter how robust, the solar hot water boom wouldn’t last. At the start of World War II,
the government put a freeze on nonmilitary use of copper, stalling out the solar hot water
heating market. After the war, the rise in skilled labor and copper prices made the collectors
less affordable. Electric prices dropped in the ’50s, making electric water heaters more
appealing. Installation and initial cost was also cheaper than solar hot water heaters. The tank
was automatic too. Solar water heating was not the same bargain anymore in the United
States, especially when oil import limits were allowed to surpass 50 percent. A similar
scenario happened later in Japan when it began importing oil in the ’60s. The peak year for
Japan’s solar hot water sales was 1966.
Throughout history, solar energy remained popular until abundant sources of fossil fuel
became available. Interest in solar energy surged during oil embargoes in 1973-74 and 1979.
Federal and state tax incentives led to rising sales in the early ‘80s. Sales flourished, but the
industry paid a high price for this brief period of prosperity. A lot of companies entered the
solar field just to make money and didn’t care about long-term relationships with their
customers. This led to poor installations and gave the industry a bad reputation. After 1985,
most of these fly-by-nighters left the solar field.
Equipment has improved since the ’80s. Improvements were precipitated by both
certification design review and experienced installers. There are more safeguards available
now to ensure competent system design and installation, such as training programs and
certification. Training is important. Like any mechanical device, all these systems have to be
serviced periodically for optimum operation. The Florida Solar Energy Center now has both
collector and system certification programs. The national Solar Rating & Certification
Corporation provides collector and system certification, as well as ratings for collectors and
systems.
Today, more than 1.2 million buildings have solar water heating systems in the United States.
This doesn’t include 250,000 solar-heated swimming pools. Japan has nearly 1.5 million
buildings with solar water heating in Tokyo. In Israel, 30 percent of the buildings use solar-heated water. Greece and Australia are also leading users of solar energy.
There is still a lot of room for expansion in the solar energy industry. There are no
geographical constraints. For colder climates, manufacturers have designed systems that
protect components from freezing conditions. Wherever the sun shines, solar water heating
systems can work. The designs may be different from the early solar pioneers, but the
concept is the same.
Solar power (electric)
Photovoltaic (PV) technology produces electricity from sunlight. The first solar powered satellite was launched in 1958 by Hoffman Electronics, and until the late 1970s solar panels were used primarily to power space satellites, lights, and small electronics like calculators and watches. In the early 1990s Germany and Japan initiated long-term PV-installation incentive programs that resulted in lower costs for solar power and spurred the growth of robust PV industries in both countries.
PV is used extensively in rural areas that are not serviced by the utility grid. These are called off grid systems. This article applies primarily to on-grid or grid-tied systems that are receiving power from an electric utility. For a wealth of information about both types of systems we recommend Home Power magazine,, and the Florida Solar Energy Center. Center
Basic System Operation: When sunlight hits the PV cells, direct current (DC) flows through the inverter, which converts it to alternating current (AC). The AC power then flows directly into the building (if there is demand), or into backup batteries if the system has them, or to the utility. When the power is flowing back to the utility grid, the electricity meter turns backward.
The Components: Photovoltaic cells are the core of the system. They are made up of at least two layers of semiconductor material (usually pure silicon infused with boron and phosphorous). One layer has a positive charge, the other a negative charge. When sunlight strikes the cell, photons from the light are absorbed by the semiconductor atoms, which then release electrons. The electrons, freed from the negative layer of semiconductor, flow to the positive layer.....thereby producing an electrical current.Since the electric current flows in one direction (like a battery), the electricity generated is called direct current (DC). Many individual cells are wired together in a sealed weatherproof unit called a solar module or solar panel.
There are three types of PV modules: single crystal, multi- or poly-crystalline, and amorphous silicon. Each of these PV types is estimated to last at least twenty-five years. Some estimate that forty years is a reasonable expectation. The longevity rating of residential solar panels or commercial solar panels refers to the number of years before the unit starts producing only 80 percent of its original power rating. For instance, some modules are warranted to produce at least 80 percent of their full-rated power after twenty-five years. Instead of stopping production completely, a PV module will gradually produce less and less power over decades. Single-crystal modules are currently the most efficient type available, meaning that they produce the most power per square foot of module. The cells are fragile so they must be mounted in a rigid frame, and the modules usually have a polka dot or checkered pattern.
Multicrystalline modules are made of cells cut from multiple crystals that are grown together in an ingot. They are similar to single crystal cells in module structure but slightly less efficient since they require a bit more surface area to produce the same amount of electricity.
Amorphous silicon modules (e.g. thin film) are made from cells created by depositing a micro-thin layer of silicon directly onto a sheet of glass, plastic, or other substrate. Although they are less efficient and require up to 50 percent more space, they can be mounted on a flexible backing, making them easier to transport and ideal for building-integrated uses, such as roofing tiles or shingles.System Design of PV
Modules are wired together into a PV array, and the electricity they produce is fed through an inverter that changes the direct current (DC) into alternating current (AC), making it suitable for homes and business, and compatible with the electric grid. The inverter is the major electronic appliance associated with a grid-tied PV system. You can learn more how you can realize your residential solar powered home or commercial one by clicking on the services section above.
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