Understanding solar power
Posted by Rahul Chitrapu on Mon, Jun 21, 2010
This is a guest post by Barbara Young. Barbara writes on motorhome solar power in her personal hobby web site 12voltsolarpanels.net. Her efforts are dedicated to helping people save energy using solar energy to lower CO2 emissions and energy dependency.
What is solar power ?
Solar energy is radiant energy that's produced by the sun. Daily the sun radiates, or sends out, an immense quantity of energy. The sun radiates more energy in one second than people have used since the beginning of time!
The energy of the Sun derives from within the sun itself. Like other stars, the sun is mostly a big ball of gases--mostly hydrogen and helium atoms.
The hydrogen atoms in the sun's core combine to form helium and generate energy in a process called nuclear fusion.
During nuclear fusion, the sun's extremely high pressure and temperature cause hydrogen atoms to come apart and their nuclei (the central cores of the atoms) to fuse or combine. Four hydrogen nuclei fuse to become one helium atom. But the helium atom contains less mass compared to four hydrogen atoms that fused. Some matter is lost during nuclear fusion. The lost matter is emitted into space as radiant energy.
It requires an incredible number of years for the energy in the sun's core to make its way to the solar surface, after which just a little over eight minutes to travel the 93 million miles to earth. The solar energy travels to the earth at a speed of 186,000 miles per second, the speed of sunshine.
Only a small part of the power radiated from the sun into space strikes the earth, one part in two billion. Yet this volume of energy is enormous. Each day enough energy strikes america to supply the nation's energy needs for one and a half years!
Where does all of this energy go?
About 15 percent of the sun's energy which hits the earth is reflected back into space. Another 30 percent is used to evaporate water, which, lifted into the atmosphere, produces rainfall. Solar energy is also absorbed by plants, the land, and the oceans. The remaining could be employed to supply our energy needs.
Who invented solar energy ?
People have harnessed solar technology for hundreds of years. As early as the 7th century B.C., people used simple magnifying glasses to concentrate the light of the sun into beams so hot they'd cause wood to catch fire. More than a century ago in France, a scientist used heat from a solar collector to create steam to drive a steam engine. At first of this century, scientists and engineers began researching ways to use solar power in earnest. One important development was obviously a remarkably efficient solar boiler introduced by Charles Greeley Abbott, a united states astrophysicist, in 1936.
The solar water heater gained popularity at this time in Florida, California, and the Southwest. The industry started in the early 1920s and was in full swing just before World War II. This growth lasted prior to the mid-1950s when low-cost natural gas became the primary fuel for heating American homes.
People and world governments remained largely indifferent to the possibilities of solar power prior to the oil shortages of the1970s. Today, people use solar technology to heat buildings and water and also to generate electricity.
How we use solar power today ?
Solar power can be used in a variety of ways, of course. There are 2 simple kinds of solar energy:
- Solar thermal energy collects the sun's warmth through 1 of 2 means: in water or in an anti-freeze (glycol) mixture.
- Solar photovoltaic energy converts the sun's radiation to usable electricity.
Let us discuss the five most practical and popular solutions solar energy is employed:
- Small portable solar photovoltaic systems. We see these used everywhere, from calculators to solar garden products. Portable units can be used for everything from RV appliances while single panel systems can be used traffic signs and remote monitoring stations.
- Solar pool heating. Running water in direct circulation systems via a solar collector is an extremely practical way to heat water for your pool or hot tub.
- Thermal glycol energy to heat water. In this method (indirect circulation), glycol is heated by the sun's rays and the heat is then transferred to water in a hot water tank. This process of collecting the sun's energy is much more practical now than ever before. In areas as far north as Edmonton, Alberta, solar thermal to heat water is economically sound. It can pay for itself in 3 years or less.
- Integrating solar photovoltaic energy into your home or business power. In most parts on the planet, solar photovoltaics is an economically feasible solution to supplement the power of your own home. In Japan, photovoltaics are competitive with other types of power. In the USA, new incentive programs make this form of solar power ever more viable in many states. An increasingly popular and practical way of integrating solar energy into the power of your home or business is through the use of building integrated solar photovoltaics.
- Large independent photovoltaic systems. When you have enough sun power at your site, you may be able to go off grid. You may also integrate or hybridize your solar power system with wind power or other types of sustainable energy to stay 'off the grid.'
How can Photovoltaic panels work ?
Silicon is mounted beneath non-reflective glass to produce photovoltaic panels. These panels collect photons from the sun, converting them into DC electrical power. The power created then flows into an inverter. The inverter transforms the power into basic voltage and AC electricity.
Solar cells are prepared with particular materials called semiconductors such as silicon, which is presently the most generally used. When light hits the Photovoltaic cell, a specific share of it is absorbed inside the semiconductor material. This means that the energy of the absorbed light is given to the semiconductor.
The energy unfastens the electrons, permitting them to run freely. Solar cells also have more than one electric fields that act to compel electrons unfastened by light absorption to flow in a specific direction. This flow of electrons is a current, and by introducing metal links on the top and bottom of the -Photovoltaic cell, the current can be drawn to use it externally.
Do you know the pros and cons of solar technology ?
Solar Pro Arguments
- Heating our homes with oil or natural gas or using electricity from power plants running with coal and oil is a cause of global warming and climate disruption. Solar power, on the contrary, is clean and environmentally-friendly.
- Solar hot-water heaters require little maintenance, and their initial investment can be recovered in just a relatively limited time.
- Solar hot-water heaters can work in nearly every climate, even just in very cold ones. Simply choose the right system for your climate: drainback, thermosyphon, batch-ICS, etc.
- Maintenance costs of solar powered systems are minimal and the warranties large.
- Financial incentives (USA, Canada, European states...) can reduce the price of the initial investment in solar technologies. The U.S. government, for instance, offers tax credits for solar systems certified by by the SRCC (Solar Rating and Certification Corporation), which amount to 30 percent of the investment (2009-2016 period).
Solar Cons Arguments
- The initial investment in Solar Water heaters or in Solar PV Electric Systems is higher than that required by conventional electric and gas heaters systems.
- The payback period of solar PV-electric systems is high, as well as those of solar space heating or solar cooling (only the solar hot water heating payback is short or relatively short).
- Solar water heating do not support a direct combination with radiators (including baseboard ones).
- Some air conditioning (solar space heating and the solar cooling systems) are expensive, and rather untested technologies: solar air-con isn't, till now, a truly economical option.
- The efficiency of solar powered systems is rather determined by sunlight resources. It's in colder climates, where heating or electricity needs are higher, that the efficiency is smaller.